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In seven difficult steps 1. Hunt for personal power Personal power is self-knowledge, self-control, self-sufficiency, self-transformation, good health, emotional strength, resilience, inner motivation, wisdom. 2. Act impeccably Generate sustained attention and effort. Choose the right challenge. Face my fears. Develop meta-attention. Plug power drains. Build good habits. Focus on the process and not the destination. Don’t get attached to goals and rewards. Use attention to perform flawlessly. 3. Take responsibility for my actions Follow my own moral code. Learn from experience. Do not complain. Do not blame others. Do not look for excuses. Do not cling to hope. Nip anger in the bud. 4. Abandon self-importance Don’t act based on pride or shame. Don’t be competitive. Don’t be defensive. Encourage my curiosity. Let go of the ego. 5. Erase personal history Do not dwell on the traumas of the past. No regrets. No self-doubt. Forget who I am and lose myself in my task. 6. Use death as an advisor Focus on things that bring meaning to my life. Accept the fact that I am going to die. Do not waste energy on unimportant things. Use my time wisely. Enjoy the present. Cultivate my love of life. Be grateful. 7. Follow a path with a heart My core motivation should be based on joy, curiosity and love. It should not be based on fear, shame or pride. Help others. Live a life worth living. Copyright 2023 Hermes Solenzol.

Flow is a mental state of focused attention in which we become productive and creative without apparent effort What is flow? You may have heard of flow, a seemingly magical state that some people enter when they write that lets them be tremendously productive and creative with little effort. Flow happens in many arts, like painting, performing music and dancing. We also hear of flow in sports. The archetypical one is rock climbing, but it can also occur in skiing, hiking, running, sailing and any other sport. It may be a bit more difficult to enter flow in competition sports, because ego gets in the way. How can flow be the same mental state in writing and rock climbing? These are very different activities. Writing is almost purely mental, while rock climbing is physical and scary. In what activities can we enter flow? Can it be just any activity? Is flow the same thing as mindfulness? Is flow real or an illusion? Does brain activity really change when we enter flow? In this article, I will answer these questions by examining the neuronal circuits in the brain that mediate flow. The six characteristics of flow Flow is a mental state of focused attention on a task—which can be an art, a mental activity or a sport—without apparent effort (“effortless effort”). It was defined in the 1970 by Mihaly Csikszentmihalyi as: “An optimal state of consciousness where we feel our best and perform our best” (Kotler et al., 2022). Csikszentmihalyi gave flow these six characteristics: Focused attention on a task. Merging of action and awareness. Decreased self-awareness. Altered perception of time, which either speeds up or slows down. Feeling of complete control. Positive emotions like joy, pleasure, euphoria, meaning and purpose. Triggers of flow According to a recent review paper (Kotler et al., 2022), the state of flow is driven by: Having clear goals. Knowing what you want to do and how you want to do it. Quick feedback. Getting clear signals about the effectiveness of your effort. Balance between challenges and skills. Flow cannot be achieved if your skills are not sufficiently developed to accomplish the task. But you don’t enter flow, either, if the task is so easy that it can be accomplished by routine or memory. Novelty and unpredictability. You enter flow when the activity that you are doing engages your curiosity and challenges your attention. Complexity. During flow, you must be learning something from your activity. Insight. Flow involves creativity, so you discover new things about your task as you do it. Risk. Some activities that induce to flow, like rock-climbing, skiing or martial arts, involve physical risk. There is an element of fear that maintains the focus of the attention. Others, like writing, performing music or painting, do not entail physical danger, but the emotional risk of failure. Awareness across multiple senses. Many of our senses are involved during flow, including interoception and muscle feedback. Curiosity. Experimentation and learning new skills are important during flow. There is basic curiosity about the outcome of the new things we try. Autonomy. Flow requires being self-sufficient and self-confident. Passion. You care deeply about what you are doing. Purpose. Flow requires an unbending will to stay engaged in your task. Mastery. Flow can only be accomplished after mastering a particular art, sport or activity. You don’t enter flow when you start learning a new sport or art because there is too much self-consciousness involved. Are there different flow states? It seems that, as long as these requisites are fulfilled, any activity can put you in a state of flow. However, it doesn’t seem logical that we have the same mental state when doing tasks as vastly different as writing and rock climbing. Surely, they engage different parts of our brain, no? Could it be that there are different states of flow with some common characteristics? In fact, in the scientific literature, there is a discrepancy about whether flow activates or deactivates the amygdala, an important part of the brain that mediates fear, aggression and other emotions. The paper by Kotler et al. proposes a thought experiment in which somebody is driving a motorcycle when a car suddenly moves into his lane, forcing him to swerve. This may not be a good example of flow because it normally does not involve a surprising, scary event, but a decision to start an activity that requires effort and concentration. Regardless, the authors describe the sequence of activation of brain areas leading to flow instead of panic. Activation of the amygdala is key in this sequence of events. The opposite case is illustrated by the studies of Ulrich et al. (Ulrich et al., 2014; Ulrich et al., 2016a, b), consisting of fMRI brain imaging in volunteers who achieved flow by doing arithmetic tasks. Of course, these did not involve surprise or fear. In this case, the amygdala became deactivated. This discrepancy suggests the existence of two types of flow. The first occurs in activities like driving a motorcycle, rock-climbing or martial arts, which involve risk and fear. In these cases, the amygdala gets activated. The second occurs in activities like performing arithmetical tasks, writing or playing music, which do not involve fear, but a calm state of mind. In these states of flow, the amygdala gets deactivated. In his book about flow (Csikszentmihalyi, 2008), Csikszentmihalyi implies that it is uniquely human. However, I think that predatory animals enter flow when they hunt. You can see it, for example, in the focused attitude of a cat stalking its prey. This suggests that there is a third modality of flow: predatory aggression (Haller, 2018). In humans, we find it in the focused attention of hunters and fishermen. While it usually does not involve fear, predatory aggression also activates the amygdala. Deactivation of the default mode network Since it was first described Mihaly Csikszentmihalyi in 1970, the brain activity that accompanies flow has been described in details by neuroscience studies like the ones cited above. When it is not in flow, the brain state consists of the default mode network. This network is are a series of interconnected brain regions that are active when we are not doing anything in particular. It is engaged we are daydreaming, thinking about ourselves, remembering the past, or planning for the future. The default mode network it is composed of the medial prefrontal cortex, the posterior cingulate cortex, the precuneus and the angular gyrus. The medial prefrontal cortex is involved in thoughts about ourselves. The posterior cingulate cortex is located deep inside the fissure that separates the brain hemispheres, behind the anterior cingulate cortex. It is involved in awareness and memory retrieval, particularly spatial and autobiographical memory. The precuneus is part of the superior parietal lobule, located halfway to the back of the brain. It is involved in the processing of visual and spatial information, episodic memory, self-awareness and consciousness. The angular gyrus is also part of the parietal lobe, located at the bottom back of it. It is involved in reading, language, processing numbers, memory and attention. It also participates in theory-of-mind: our ability to create mental models of what goes on in other people’s minds. During flow, the default mode network becomes deactivated. Activation of the saliency network Kotler et al. propose that flow is initiated by a shift from the default mode network to the saliency network. Although they propose that this shift is triggered by a surprising event, it could also be produced by the struggle to perform a difficult task, or by the decision to focus the attention on a task. The saliency network is in charge of increasing the importance of certain stimuli by presenting them to consciousness (salience), while other stimuli are relegated to the background and remain unconscious. Salient feelings are those that are important for survival—like pain, pleasure, disgust and fear. Other salient stimuli are important for reproduction—like sexual desire, seeing a loved one or caring for children. However, if we have decided that a task—like writing or playing music—is important for us, anything related to that task becomes salient. The saliency network is primarily formed by the dorsal anterior cingulate cortex and the anterior insula. It also includes the inferior parietal cortex, the right temporoparietal junction, the pre-supplementary motor area and the lateral prefrontal cortex. The primary function of the anterior cingulate cortex is to select plans for action. It does that by identifying conflicts and errors in executing actions, and discovering new action plans. In the flow state, this leads to creativity. The anterior insula also mediates the monitoring of performance and error processing, using its capacity to anticipate the state of the body as a result of a certain action. Involvement of the dopamine pathways The activity of the saliency network is dependent on the striatal dopaminergic pathway (Wise and Robble, 2020). Dopamine neurons are located in a region of the midbrain called the ventral tegmental area (VTA), and also in the substantia nigra. Axons going from the VTA to the nucleus accumbens form the reward pathway, where addictive drugs induce craving. Dopamine neurons from the VTA also project to the dorsal anterior cingulate cortex and the prefrontal cortex, playing a key role in maintaining focus in whatever we are doing. The VTA is activated when the salience network receives sensations that are novel, rewarding, or that conflict with ongoing expectations. There are two types of dopamine neurons in the VTA: Value-coding neurons are activated by unexpected rewards and inhibited by unexpected distressing events. They project to the shell of the nucleus accumbens and to the ventromedial prefrontal cortex. Saliency-coding neurons are activated by the incentive value of new information, motivating us to act. They project to the core of the nucleus accumbens and to the dorsolateral prefrontal cortex. During flow, the struggle to start a hard task initially decreases dopamine release from the value-coding neurons. Once we have overcome this struggle period, the saliency network drives dopamine release from the saliency-coding neurons that connect the VTA with the anterior cingulate cortex and the dorsolateral prefrontal cortex. In these brain regions, dopamine helps sustain effort-based decision-making, leading to tenacity, grit and resilience. This creates the feeling of effortless effort during flow. However, another part of the prefrontal cortex, the medial prefrontal cortex, gets inhibited during flow. The medial prefrontal cortex is part of the default mode network and mediates thoughts about our self, our past and our future. Its inhibition is what produces the selfless feeling characteristic of flow. Engagement of the executive attention network As the state of flow gets established, the salience network induces the activation of the executive attention network. While the salience network is activated by stimuli that are important for survival, the executive attention network is engaged when the brain takes charge and directs the attention. The executive attention network is involved in cognitive control, working memory, sustained attention and the solving of complex problems. It is also called the frontoparietal network, and is formed by the rostral lateral and dorsolateral prefrontal cortex and the posterior parietal cortex. One key function of the executive attention network is sensory-gating: filtering out sensations that are not relevant to the task at hand. This happens when the prefrontal cortex inhibits the reticular nucleus of the thalamus. The thalamus is located in the center of the brain, and is a hub where different sensory stimuli are processed, filtered and directed to different areas of the cortex. Therefore, the prefrontal cortex directs the thalamus to select sensations that are related to the task that we are doing, and to inhibit the rest. The amygdala and the locus coeruleus As I said above, there are two different types of flow, depending on whether the amygdala gets activated or inhibited. While the type of flow involved in writing inhibits the amygdala, the type of flow involved in rock climbing activates it. The amygdala is the area of the brain that mediates fear, anxiety, aggression and other emotions. It is connected to the dopamine reward pathway of the striatum. It has two main parts: Basolateral amygdala, involved in the three responses to stress: fight, flight and freezing. Central amygdala, involved in the formation and storage of fear memories. The central amygdala sends axons to two areas in the brain that initiate pain inhibition: the periaqueductal gray (PAG), which is the origin of the endorphin analgesic pathway, and the locus coeruleus, which is the origin of the norepinephrine analgesic pathway. The locus coeruleus is critical for flow. It not only sends norepinephrine-releasing axons to the spinal cord to inhibit pain, but also to different areas of the cortex, where they maintain attention. These include: Dorsomedial prefrontal cortex, where norepinephrine increases focus and performance. Ventrolateral orbitofrontal cortex, where it reduces impulsivity (the urge to take careless action), which is essential for purposeful control. Temporal parietal junction, where it increases empathy. Dorsal anterior cingulate cortex, which is involved in action planning. Its feedback to the amygdala serves to sustain flow. Noradrenergic projections from the amygdala to the hypothalamus activate the hypothalamus-pituitary-adrenal (HPA) axis, leading to increases in cortisol and adrenaline in the blood. This hormonal stress response increases the heartbeat to sustain muscular activity. However, it seems that activation of the amygdala, locus coeruleus and HPA axis is important in the rock climbing type of flow, but not is the writing type of flow. The former, but not the latter, is triggered by the perception of danger. The fear caused by a risk activity can lead to three different stress responses: fight, flight or freeze. Only the first takes us into flow. Here, fight doesn’t mean aggression, but engaging with the source of fear. In contrast, flight means avoiding the challenge, maybe by procrastinating or daydreaming instead of performing the activity. Freeze means becoming passive. There is a switch in the brain that puts it into fight mode instead of flight or freezing. It is located in the thalamus, the area in the center of the brain that serves to sort out sensory information on its way to the cortex. The freeze response is mediated by the xiphoid nucleus (Salay et al., 2018), located in the ventral midline of the thalamus. Fight responses are mediated by projections from the nucleus reuniens, which surrounds the xiphoid nucleus, to the medial prefrontal cortex. Flow and mindfulness Flow is not the same as mindfulness, although both states support each other when we practice them. In mindfulness, our conscience is passive, taking in incoming feelings without judging them. It activates the salience network. In flow, our consciousness is in an active state. In it, the executive attention network takes over the salience network. Unlike mindfulness, in flow our consciousness selects the sensations necessary to perform a task instead of giving equal weight to all stimuli. Although both mindfulness and flow turn off judging, they do it in different ways. In flow, the inhibition of the medial prefrontal cortex makes us forget about our self. The activity that we are doing completely fills our consciousness. One type of judging remains: the feedback from our activity. But it doesn’t involve self-criticism. In mindfulness, judging is turned off purposely by looking at all stimuli with equanimity. Final remarks I have shown here that the brain circuits that mediate flow are quite well understood. One consequence of this is that neuroscience is beginning to understand consciousness quite well. Unlike being something ethereal and separated from the mind, as proposed by some mystics and philosophers, consciousness exists in different states, each controlled by its own neuronal network in the brain. These states include the default state, mindfulness and flow. Learning to enter flow can help us work at our jobs with a feeling of fulfillment and effortlessness. If we engage in artistic activities, it will increase our creativity and take us to the edge of our capabilities. Other states of flow can be entered while doing sports. When danger is present, as in rock climbing or skiing, flow let us use our fear to increase our focus, thereby decreasing the risk by maximizing our performance. However, we don’t need to practice a difficult art or a dangerous sport to enter flow. Any activity can lead us to this mental state if we find a way to challenge ourselves while doing it. The key is to avoid mechanical action and daydreaming, which keep our brain in the default network. During Zen retreats (sesshins), I was taught how to stay mindful while doing menial tasks like cutting vegetables, washing dishes or sweeping the floor. The determination of staying completely focused on the task created a challenge that put me in a state of flow. Flow feels great! When we learn how to enter it, there are no more boring tasks, no more unpleasant work. Every task can be joyful because what matters is not what we do, but the mental state in which we do it. Like any other mental activity, flow is habit-making. This means that, once your brain learns to go into flow, it becomes easier and easier to enter that state. As we do more and more activities in a state of flow, it becomes a way of life. One that leads us to a life worth living. References Csikszentmihalyi M (2008) Flow: The Psychology of Optimal Experience: HarperCollins eBook. Haller J (2018) The role of central and medial amygdala in normal and abnormal aggression: A review of classical approaches. Neurosci Biobehav Rev 85:34-43. Kotler S, Mannino M, Kelso S, Huskey R (2022) First few seconds for flow: A comprehensive proposal of the neurobiology and neurodynamics of state onset. Neuroscience & Biobehavioral Reviews 143:104956. Salay LD, Ishiko N, Huberman AD (2018) A midline thalamic circuit determines reactions to visual threat. Nature 557:183-189. Ulrich M, Keller J, Grön G (2016a) Neural signatures of experimentally induced flow experiences identified in a typical fMRI block design with BOLD imaging. Soc Cogn Affect Neurosci 11:496-507. Ulrich M, Keller J, Grön G (2016b) Dorsal Raphe Nucleus Down-Regulates Medial Prefrontal Cortex during Experience of Flow. Frontiers in behavioral neuroscience 10:169. Ulrich M, Keller J, Hoenig K, Waller C, Grön G (2014) Neural correlates of experimentally induced flow experiences. NeuroImage 86:194-202. Wise RA, Robble MA (2020) Dopamine and Addiction. Annu Rev Psychol 71:79-106. Copyright 2023 Hermes Solenzol.

A person being choked may have a cardiac arrest or become unconscious. This is what you should do. I strongly recommend not to practice choking. This article is part of a series intended to show that choking is unsafe, may cause brain damage, and is potentially lethal. The advice I give here is intended to mitigate the damage caused by choking. It does not make choking safe. There are no warrantees that any of this will work. You may find that a partner that you just choke is unconscious and unresponsive. Don’t panic. Never, ever, leave your partner and run away! He or she will probably die, and you will probably end up spending many years in jail. Is there a cardiac arrest? Cardiac arrest - when the heart stops beating - is a rare occurrence during breath play, but a definite possibility. It is very hard to predict. Even a healthy person who has been choked many times can go into cardiac arrest. The first thing you should do is to check for a heartbeat. If there is none, you have a life-threatening problem. As I explained in previous articles in this series, a blood choke can induce cardiac arrest by messing with the sensing of blood pressure in the carotid sinuses. If the heart stops beating, every second counts to save your partner’s life. If there are people around who can reach you, call out for help. No matter who they are. No matter if you and your partner are naked. You need as many people as you can, so that somebody can make an emergency call, while somebody does cardiopulmonary resuscitation (CPR) and somebody else goes searching for an automated external defibrillator (AED). If you are alone, call immediately 911 (in the USA) or a similar emergency number in your country. If you put your cell phone in speaker mode, you should be able to make that call while you start CPR. CPR may bring back a person with cardiac arrest, but chances are that it may not. Regardless, you should continue CPR until a rescue team arrives. CPR can maintain enough blood circulation and oxygenation to keep the brain alive. You can learn CPR online here. Using an automated external defibrillator (AED) If you have access to an AED, you should use it. But don’t leave your partner alone to go looking for one. AEDs are those electric pads that we see in the movies being used in hospitals. You place them diagonally across the chest, shout “clear!” and press a button to deliver a shock to the heart to start it beating again. Most CPR classes will teach you how to use an AED. These days, many public places like shopping malls, public transportation and movie theaters have AEDs. If you are in a public dungeon of a BDSM club, they will probably have one. The Staying Alive app, by Le Bon Samaritain, can be installed for free on your cell phone and can show you where the nearest AED is located. It also shows you how to use one. You can buy or rent an AED, to have it handy if you practice choking. Unconsciousness but no cardiac arrest Much more common than cardiac arrest would be a situation in which the person who has been choked has a pulse but remains unconscious. You should be able to restore consciousness with assisted breathing, either mouth-to-mouth or with chest compressions. While you do that, keep checking the pulse and watch out for vomiting. A person who needs rescue breathing to regain consciousness should be taken to an emergency room or urgent care facility for examination. This is particularly important if the person experiences problems with balance, vision abnormalities, slurred speech or persistent dizziness. Keep in mind that a person in this condition may not be fully capable of making decisions and may misjudge their state. Even if they don’t seek medical attention right away, they need to be closely watched. Don’t leave them alone. Ideally, a person who has been unconscious for lack of oxygen for more than a few seconds should be examined by a doctor for signs of brain damage a few days after the incident. Brain imaging and other test can detect if some areas of the brain have been injured. There are medication and treatments to help the brain recover. If a person has been unconscious and has dizzy spells, headaches, nausea, blurred vision or difficulty speaking, they need to see a doctor right away. Knowing CPR doesn’t make choking safer What I wrote above is meant to increase the chances of survival in case of an accident during sexual choking. It should not be taken as an endorsement of this practice or as a reassurance that knowing CPR makes choking any less dangerous. In the words of Jay Wiseman, the author of SM 101: A Realistic Introduction: “It's good for people to learn CPR. […] That said, should breath play result in a cardiac arrest, it cannot be reasonably said that doing CPR is reliably likely to revive the victim. Cardiac arrest is a completely out of control disaster. Resuscitation is certainly not guaranteed even for a very experienced and highly trained medical team with all advanced life support equipment immediately available. An inexperienced and minimally trained civilian, likely working alone, faces a much more uphill battle. In the unlikely event that an automatic external defibrillator (AED) was available it should certainly be used, but the battle nonetheless remains very much an uphill one. While CPR training can reasonably be said to mitigate some of the "lesser" risks of breath play, such as respiratory arrest or airway obstruction by the victim's own tongue, it cannot reasonably be said that CPR training significantly mitigates the "greater" risk of a fatal outcome due to cardiac arrest.” Jay Wiseman's "Closing Argument" On Breath Play. If don’t want to be in a situation in which you have to fight to bring your partner back to life or, even worse, watch them die, don’t do sexual choking. Copyright 2023 Hermes Solenzol.

Is the euphoria produced by exercise mediated by opioid receptors or cannabinoid receptors? The endorphin rush The endorphin rush is an expression widely used in popular culture that refers to feelings of euphoria, elation, endurance, and decreased anxiety and pain supposedly caused by the release of endorphins in the brain. The endorphin rush has sunk deep roots in the popular culture. There are drinks and rock bands named after it. It is considered responsible for increasing the performance of athletes, the pleasure of sex and even “sub space”—an altered state of consciousness produced by pain in masochists. The runner’s high But the most well-known example of an endorphin rush is the runner’s high. A marathon runner is about to hit the wall. His energy is depleted, he is exhausted, and his legs are about to give up. But, all of a sudden, something magical happens. He feels full of energy and can complete the race, running even faster. All the anxiety is gone and, in fact, he feels totally happy. What happened? Well, his brain resorted to a last-resort trick. It released a bunch of endorphins that relieved his fatigue and made him high. That was the story that we have been told for a long time. But now it turns out that it may not be the endorphins after all, but some marihuana-like compounds called endocannabinoids. This article looks at the evidence for both explanations. In the process, it will explain some interesting facts about the brain and the methods that scientists use to explore it. Endorphins and opioid receptors “Endorphins” is the name popularly given to endogenous opioids, a large family of peptides found in the brain and the blood that are able to activate the opioid receptors used by drugs like morphine, heroin, fentanyl and codeine. There are three classic opioid receptors, designated by the Greek letters mu, delta and kappa. A fourth receptor and its corresponding peptide were discovered simultaneously by two groups, so it was given the two names that they used: the nociceptin/orphanin receptor. However, this receptor does not produce euphoria or analgesia, so I will leave it out of this discussion. Endorphins are peptides encoded by three genes: proopiomelanocortin (POMC), proenkephalin and prodynorphin. If Nature was well-organized and rational, each of these genes would encode a peptide that would activate each of the three classic opioid receptors, and that would be that. Alas! Nature is neither simple nor rational. In fact, it displays a perverse penchant to make things convoluted. And so each gene encode for a complex mixture of peptides: enkephalins, dynorphins and beta-endorphin. To make things even more fun, the POMC gene also encodes for two peptides that have nothing to do with opioids and their receptors. One is alpha-melanocyte-stimulating hormone (alpha-MSH), which regulates appetite and sexual behavior. The other is adrenocorticotropic hormone (ACTH), which is part of the stress response of the hypothalamus-pituitary-adrenal (HPA) axis. See? I told you Nature was devious. So, let’s try to keep things simple for this discussion. Enkephalins and beta-endorphin bind to mu and delta opioid receptors, that produce analgesia and euphoria. Dynorphin binds to kappa receptors that produce analgesia and dysphoria—the opposite of euphoria. Measuring endorphins in the blood or the saliva is meaningless Initial studies on the runner’s high measured endorphin in the blood or the saliva of runners, and found that running and other types of exercise increased them. However, this is meaningless. Endorphins do not cross the blood-brain barrier, a wall in the capillaries of the brain that makes its chemical environment totally different from that of the blood. So endorphins in the blood cannot induce euphoria or analgesia, because these effects are produced by neurons in the brain. On top of that, endorphins (mainly the beta-endorphin encoded by the POMC gene) are released into the blood from the pituitary gland at the same time as ACTH, which is also encoded by the POMC gene. Since ACTH release is part of the stress response, endorphin in the blood does not produce euphoria. In fact, when endorphins are released in some parts of the brain (the locus coeruleus), they turn off the stress response. Hence, to determine if the runner’s high is mediated by endorphins, we need to measure them in the brain of the runners. A study of endorphin release in the brain of runners Measuring endorphins in the brain of humans while they are awake—in fact, shortly after they performed a strenuous exercise—may seem like an impossible task. However, it can be done by using a fancy technique called positron emission tomography (PET). PET uses drugs that incorporate unstable isotopes like fluor-18 (18F) or carbon-11 (11C). These drugs are called radiotracers. When the isotopes decay, they release a positron. It interacts with an electron, producing a gamma ray, which is detected by the PET machine. When the radiotracer drug is bound to a receptor, like the mu-opioid receptor, it stays longer in that brain region, which gives a brighter PET signal. However, if endorphins are released in that brain region, they displace the radiotracer from the receptor, so the PET signal decreases. This allows scientists to create images of the brain where endorphin release is color-coded and quantified. The first study that investigated the runner’s high with PET (Boecker et al., 2008) used as radiotracer [18F]FDPN, an opioid drug that binds to all the classical opioid receptors. The subjects were 10 male runners who had experienced the runner’s high before and trained for a minimum of 4 hours weekly for the last 2 years. These inclusion criteria were important because they ensured that the effects studied were really a runner’s high and not mere responses to exercise or fatigue. Thirty minutes after a two-hour run, the subjects received an injection of the radiotracer and had their brains scanned with PET. As control, they had a PET scan after 24 hours without exercise. These two PET scans were separated by 4 weeks and their order was randomized. The results were shown as endorphin release after running compared with rest for each subject. An increase in endorphins was found in the following brain regions: orbitofrontal cortex—a region of the prefrontal cortex that assigns value to actions, evaluates contingencies and appraises emotions; dorsolateral prefrontal cortex—involved in decision making, cognitive flexibility, working memory and planning; insula—an area of the cortex buried inside the brain hemispheres that is involved in pain, pleasure, euphoria and other emotions; anterior cingulate cortex—a region of the cortex between the hemispheres that controls motivation, detects errors and conflicts, and plans actions; posterior cingulate cortex—involved in spatial memory, emotional saliency and learning; sensory and motor cortex—involved in detecting sensations and directing muscle contraction, respectively. The runners were also given a psychological test to evaluate their emotions after running. Two emotions increased after running: happiness and euphoria. This indicated the presence of the runner’s high. Other emotions didn’t change after the run, including confusion, anger, sadness, fatigue, fear, energy and tension. Finally, the scientists analyzed both sets of data together to determine if there was a correlation between the feelings of euphoria and endorphin release in each brain area. A positive correlation between endorphin release and euphoria was found in the orbitofrontal cortex, dorsolateral prefrontal cortex, anterior and posterior cingulate cortex, insula, sensory cortex and motor cortex. These results strongly support the idea that the runner’s high is a feeling of euphoria caused by endorphin release in brain areas that process emotions and direct actions. Endorphin release in the brain during moderate and intense exercise Ten years later, another study (Saanijoki et al., 2018) used PET scanning to find out if moderate and intense exercise are equally able to induce endorphin release. Another difference with the previous PET study is that they used a radiotracer, [11C]carfentanil, that is a selective agonist of mu-opioid receptors. The previous study used [18F]FDPN, which could also bind to the kappa opioid receptors and therefore detect the release of dynorphins in addition to enkephalins and endorphins. Remember that dynorphins binding to kappa opioid receptors produce dysphoria, the opposite of what the endorphin high is supposed to be. But perhaps the most relevant differences were the subjects and the type of exercise. The 22 subjects were also men, but there was no requirement of them to have previously experienced the runner’s high or to exercise regularly. The exercise used in the experiments was not running, but indoor cycling. Moderate intensity exercise was defined as cycling for 1 hour “at workload in the middle between aerobic and anaerobic thresholds,” which were determined previously. High-intensity interval training (HIIT) consisted of five cycling sprints of 30 seconds at maximal load, separated by 4 minutes rests. They found that HIIT, but not moderate intensity exercise, induced endorphin release in many brain areas. Some were the same areas identified in the previous study: dorsolateral prefrontal cortex, orbitofrontal cortex, anterior and posterior cingulate cortex, thalamus and insula. In addition, they found endorphin release in the ventral striatum, hippocampus, cerebellum, amygdala and periaqueductal gray (PAG). The ventral striatum contains the ventral tegmental area (VTA) and the nucleus accumbens, which form the dopamine reward pathway that mediates motivation and drug addiction. The amygdala mediates fear and controls the stress response. The PAG is the beginning of a neuronal pathway that goes from the brainstem to the spinal cord and inhibits pain. Again, psychological tests were used to determine if the subjects had a runner’s high. They were taken by 12 subjects that did both types of exercise. Surprisingly, euphoria, motivation and satisfaction were higher during moderate-intensity exercise than during HIIT. Conversely, negative feelings like exhaustion, tension and irritation were higher during HIIT than during moderate exercise. Pain increased with exercise and it was not different between HIIT and moderate exercise. Even more unexpected was the finding that the negative feelings during HIIT correlated with endorphin release, particularly in the dorsal prefrontal cortex. Moreover, the euphoria produced by moderate exercise also correlated with endorphin release in the dorsal prefrontal cortex. So, there is no endorphin rush? This second study brought into question the idea of the endorphin rush. On the one hand, yes, exercise releases endorphins in the brain. And intense exercise releases more endorphins than moderate exercise. But, instead of being associated with euphoria and feelings of energy, which is the classic description of the runner’s high, endorphin release during intense exercise correlated with negative emotions like exhaustion and irritation. On top of that, moderate exercise produced euphoria and other positive feelings. All of these contrasts with the common description of the runner’s high, which is only achieved after hitting a wall of exhaustion during extreme exercise. So, endorphin release during intense exercise does not produce euphoria? There is no endorphin rush? The answer may be a bit more complicated. Maybe what happens is that endorphins are released during exercise as a compensatory response to negative feelings like pain, anxiety, irritation and exhaustion. With moderate exercise, they are able to eliminate these feelings and even produce euphoria. But with intense exercise, the negative feelings are so strong that endorphins cannot drown them. These negative feelings may be mediated by neuropeptides like dynorphins, corticotropin-releasing factor (CRF) and cholecystokinin (CCK). CRF drives the stress response of the HPA axis and the locus coeruleus. CCK induces anxiety and opposes the effects of endorphins. Mice do not have an endorphin rush Meanwhile, some scientists raised the possibility that the runner’s high was mediated by endocannabinoids instead of endorphins. Endocannabinoids are to cannabinoid receptors what endorphins are to opioid receptors. They are substances produced in the body that activate the same receptors as the psychoactive compounds in cannabis. The two main endocannabinoids are anandamide and 2-arachydonoyl-glycerol (2-AG). The high produced by marihuana is mediated by CB1 receptors, which are abundant in the brain. There are at least two other cannabinoid receptors, CB2 and GPR55, which do not mediate the psychotropic effects of cannabis but some of its other effects on the body. A study in mice (Fuss et al., 2015) showed that, when mice exercise on a running wheel, they have less anxiety and pain. They also had elevated levels of endocannabinoids in their blood. The analgesia produced by exercise was eliminated by blocking CB1 and CB2 receptors with their antagonists, but not by blocking opioid receptors with naloxone. This indicated that the pain reduction was mediated by endocannabinoids and not by endorphins. Similarly, the decrease in anxiety produced by exercise was blocked by antagonists of CB1 receptors, but not by antagonists of CB2 receptors or by naloxone. In a sophisticated experiment, the scientists selectively eliminated CB1 receptors in GABA-releasing neurons in the forebrain of mice using transgenic techniques. These mice ran less on the wheel than normal mice and lose the anxiolytic effect of running. This showed that the decrease in anxiety produced by wheel running in mice is mediated by CB1 receptors in forebrain neurons. However, this study does not tell us much about the runner’s high because its main characteristic is euphoria, and euphoria cannot be studied in mice. What it shows is that exercise decreases pain and anxiety in mice, and that these effects are mediated by the action of endocannabinoids in the forebrain. However, the analgesic and anxiolytic effects of cannabinoids have been known for a while. So, it’s not endorphins but the endocannabinoids? To see if endocannabinoids are responsible for the euphoria of the runner’s high, the same group performed their next experiments in humans (Siebers et al., 2021). The obvious experiment would be to repeat the first two studies with PET scanning, but with a radiotracer that binds to cannabinoid receptors instead of opioid receptors. Indeed, there are several radiotracers for CB1 receptors (Horti et al., 2006; Varlow et al., 2020; Hou et al., 2021). However, this study did not use them. Instead, they did three experiments. The first consisted of measuring endocannabinoids in the blood before and after exercise, which consisted of walking or running on a treadmill for 50 minutes. The second experiment consisted of a battery of psychological test to measure euphoria before and after the exercise. The subjects were injected with naltrexone, a mu-opioid receptor antagonist. If naltrexone decreased the euphoria, then it was mediated by endorphins. A more complete design would have used also CB1 receptors antagonists, like in the experiments with mice. Unfortunately, CB1 antagonists have not been authorized to be used in humans. Rimonabant, an antagonist of CB1 and CB2 receptors, was used in humans for a while, but withdrawn (Sam et al., 2011). The third experiment was a sophisticated way to measure anxiety, called the human elevated plus-maze. The subjects were made to walk on wooden planks forming a plus sign while wearing a virtual reality (VR) headset. In one direction (closed arm), the headset showed the planks surrounded by protective rock walls. In the other direction (open arm), the VR headset showed a 55 meter (180 feet) fall to either a river of icy water or a parking lot with cars. The time the subjects spent in the open arm was a measure of their anxiety levels. Both walking and running increased endocannabinoids in the blood, but running produced a larger increase than waking. Running, but not walking, produced euphoria. Naltrexone produced a small decrease in euphoria that was not statistically significant. As for the fancy experiment with the VR headset to measure anxiety, the results were rather meager. After running, the subjects experienced marginally less anxiety than after walking (p = 0.024). Naltrexone did not change the anxiety levels in either condition. This study was touted by the press as showing that the runner’s high is mediated by endocannabinoid and not by endorphins. Sensational news! People had been fooled into believing in the endorphin rush all along. My conclusion: it’s the endorphins, after all However, I have my doubts. The paper by Siebers et al. did not invalidate the two original studies using PET imaging to measure endorphin release in the brain. In fact, those two studies were of much higher quality than the one by Siebers et al. The two PET studies demonstrated the endorphins are released by exercise in brains areas relevant for controlling pain, mediating emotions and inducing euphoria. They were done by different groups and, in these measures, they were consistent which each other. The main thing in question is whether the endorphins released by exercise produce euphoria. In this, the two PET studies reached conflicting conclusions. The one by Boecker et al. showed that strenuous running produced euphoria. The one by Saanijoki et al. showed that only moderate exercise produced euphoria, which correlated with endorphin release. Intense exercise produced negative emotions, which also correlated with endorphin release. As I pointed out before, these results can be reconciled if we assume that endorphin release is a compensatory response that can reverse the negative emotions produced by moderate exercise, but not by intense exercise. But, what about the third study arguing that the euphoria is mediated by endocannabinoids? Its results are far from compelling. It showed only that the reduction is euphoria produced by naltrexone was not statistically significant—which is not the same as proving that naltrexone had no effect on euphoria. That would require a different statistical test, one that shows that euphoria with and without naltrexone is statistically the same. Hence, it is possible that naltrexone decreased euphoria, but this effect was not statistically significant due to the experimental design of this study. And it did not show that euphoria was caused by endocannabinoids, or that there was cannabinoid receptor activation in areas of the brain that mediate euphoria. The results of the anxiety tests by Siebers et al. were even less conclusive. The effect of running on anxiety was too small when compared to walking. A key control is missing: anxiety measures at rest. This should be compared with anxiety after walking. If we don’t have a clear decrease in anxiety produced by exercise, testing the effect of naltrexone on this small effect is meaningless. Endocannabinoids are released in the blood by exercise, for sure. But, although they cross the blood-brain barrier, this is not the same as endocannabinoids being released in brain areas that mediate euphoria, which is what the two PET imaging studies showed for endorphins. If we don’t know in which brain areas the endocannabinoids are released, we cannot propose a mechanism by which they induce euphoria. Besides, cannabinoids decrease anxiety, but they do not produce the high levels or euphoria induced by the opioid drugs and the endorphins. I think that the main source of confusion is the assumption that any strenuous exercise is going to automatically induce a runner’s high. This is not the experience of runners. The runner’s high is an altered state of consciousness that is encountered only by a selected group of runners after extremely long runs. It is probably a learned response. Only the first study (Boecker et al., 2008) selected runners who had already experienced the runner’s high and that said that they achieved that state during the experiment. The second study (Saanijoki et al., 2018) did not even select athletes who trained regularly. The third (Siebers et al., 2021) selected subjects who performed “endurance exercise more than twice a week,” but did not check if they experienced a runner’s high. My conclusion is that exercise releases endorphins and endocannabinoids. It induces a variety of positive and negative emotional states, mediated by euphoric (endorphins, endocannabinoids) and dysphoric (dynorphins, CRF, CCK) neurotransmitters. However, only in some special situations endorphin release raises to the level to produce the high euphoria seen in the runner’s high. The endorphin rush is not automatic. It seems to require entering some sort of trance state, or breaking through a neurophysiological barrier. References Boecker H, Sprenger T, Spilker ME, Henriksen G, Koppenhoefer M, Wagner KJ, Valet M, Berthele A, Tolle TR (2008) The Runner's High: Opioidergic Mechanisms in the Human Brain. Cerebral cortex (New York, NY : 1991). Fuss J, Steinle J, Bindila L, Auer MK, Kirchherr H, Lutz B, Gass P (2015) A runner's high depends on cannabinoid receptors in mice. Proceedings of the National Academy of Sciences 112:13105-13108. Horti AG, Fan H, Kuwabara H, Hilton J, Ravert HT, Holt DP, Alexander M, Kumar A, Rahmim A, Scheffel U, Wong DF, Dannals RF (2006) 11C-JHU75528: A Radiotracer for PET Imaging of CB1 Cannabinoid Receptors. Journal of Nuclear Medicine 47:1689-1696. Hou L, Rong J, Haider A, Ogasawara D, Varlow C, Schafroth MA, Mu L, Gan J, Xu H, Fowler CJ, Zhang MR, Vasdev N, Ametamey S, Cravatt BF, Wang L, Liang SH (2021) Positron Emission Tomography Imaging of the Endocannabinoid System: Opportunities and Challenges in Radiotracer Development. J Med Chem 64:123-149. Saanijoki T, Tuominen L, Tuulari JJ, Nummenmaa L, Arponen E, Kalliokoski K, Hirvonen J (2018) Opioid Release after High-Intensity Interval Training in Healthy Human Subjects. Neuropsychopharmacology 43:246-254. Sam AH, Salem V, Ghatei MA (2011) Rimonabant: From RIO to Ban. Journal of Obesity 2011:432607. Siebers M, Biedermann SV, Bindila L, Lutz B, Fuss J (2021) Exercise-induced euphoria and anxiolysis do not depend on endogenous opioids in humans. Psychoneuroendocrinology 126:105173. Varlow C, Boileau I, Wey HY, Liang SH, Vasdev N (2020) Classics in Neuroimaging: Imaging the Endocannabinoid Pathway with PET. ACS Chem Neurosci 11:1855-1862.

Several surveys found that nearly a majority of college students use choking during sex I strongly recommend not to practice choking. This article is part of a series intended to show that choking is unsafe, may cause brain damage, and is potentially lethal. Sexual choking is not exclusive of BDSM, and has become prevalent among the young. In a survey of 4,989 US college students, 58% of women had been choked during sex at least once (Herbenick et al., 2021). Another survey of undergraduate students (Herbenick et al., 2022a) found that 37% of the women and 7% of the men had been choked more than five times. Strangulation is also increasingly a feature of sexual assault. It is also used non-consensually during sex that was consensual up to that point. However, I will limit this discussion to consensual choking. Yet another survey of undergraduate and graduate students (Herbenick et al., 2022b) studied closely sexual choking in terms of prevalence, characteristics and physical responses. The survey was given to 13,449 students, of which 4,254 completed it. Men were 49.6% of the responders, women 48.1% and transgender/non-binary 2.2%. Age differences The survey found that 30% to 40% of the responders have practiced choking during sex. By comparing the responses of the older graduate students with the younger undergraduates, it found that choking is more prevalent among the young. The percentage of people doing the choking was 37.1% among the undergraduates and 27.6% among the graduate. The percentage of those being choked was 42.1% of the undergraduates and 32.1% of the graduates. Therefore, choking is more frequent in the younger generations, a sign that is increasing over time. Choking was less prevalent among people over 40 (Herbenick et al., 2023). Gender differences There were also substantial gender differences. Men did more choking (47.4% undergraduates, 37.7% graduates) than women (26.7% undergraduates, 16.2% graduates). Conversely, men were choked (25.4% undergraduates, 23.5% graduates) less frequently than women (57.6% undergraduates, 41.3% graduates). In transgender/non-binary people, choking (45.0%) and being choked (51.5%) were even more prevalent. In summary, men prefer to do the choking while women prefer to be choked. A majority of the women and transgender people in this sample have experienced choking. References Herbenick D, Fu TC, Patterson C (2023) Sexual Repertoire, Duration of Partnered Sex, Sexual Pleasure, and Orgasm: Findings from a US Nationally Representative Survey of Adults. J Sex Marital Ther 49:369-390. Herbenick D, Guerra-Reyes L, Patterson C, Rosenstock Gonzalez YR, Wagner C, Zounlome N (2022a) "It Was Scary, But Then It Was Kind of Exciting": Young Women's Experiences with Choking During Sex. Arch Sex Behav 51:1103-1123. Herbenick D, Patterson C, Beckmeyer J, Gonzalez YRR, Luetke M, Guerra-Reyes L, Eastman-Mueller H, Valdivia DS, Rosenberg M (2021) Diverse Sexual Behaviors in Undergraduate Students: Findings From a Campus Probability Survey. The journal of sexual medicine 18:1024-1041. Herbenick D, Fu TC, Eastman-Mueller H, Thomas S, Svetina Valdivia D, Rosenberg M, Guerra-Reyes L, Wright PJ, Kawata K, Feiner JR (2022b) Frequency, Method, Intensity, and Health Sequelae of Sexual Choking Among U.S. Undergraduate and Graduate Students. Arch Sex Behav. Copyright 2023 Hermes Solenzol.

Is it just to please a partner, for pleasure, or something else? I strongly recommend not to practice choking. This article is part of a series intended to show that choking is unsafe, may cause brain damage, and is potentially lethal. Many people finds been choked pleasurable In their survey of undergraduate and graduate students, the group of Herbenick (Herbenick et al., 2022b) found that 41.1% of the people who had been choked reported that choking was very pleasurable, 33.8% responded that it was somewhat pleasurable and 14.2% said that it was a little pleasurable. Only 3.1% said that choking was not pleasurable at all and didn’t want to repeat the experience, while 5.9% said it was not pleasurable but they would do it if their partners liked it. Please note that saying that a sexual act is done to please a partner does not make it non-consensual. It is not just that women accept being choked to please their partner; some men choke women only because they are asked to do it. More women than men found choking pleasurable, with 50.0% of undergraduate women and 26.8% of undergraduate men saying that it was very pleasurable. The number of graduate students that found it very pleasurable was 36.1% for women and 16.3% for men. Hence, a large majority of the students found breath play pleasurable. This can explain the growing popularity of choking, despite its reputation for being dangerous. However, this paper did not inquire into what made choking pleasurable. Consent Regarding consent, people who had been choked said that choking was consensual 92.1% of the time (Herbenick et al., 2022b). This number did not change much across genders or from undergraduates to graduate students. Among those who had been choked, choking was found to be consensual in all of their sexual encounters by 76.5% of women, 85.6% of men and 63.6% of non-binary people. In a more general survey about sex amongst college students (Herbenick et al., 2021), 21% of the students who had been choked said that they had never been asked for consent before being choked. An additional 32% of them said that they were asked for consent only sometimes. A qualitative survey (Herbenick et al., 2022a) found that the initial choking experience of many women occurred without discussing it beforehand or giving explicit consent. Often, consent was assumed or was sought while it happened. The authors remarked that consent to choking often fell in a gray area. For example, when verbal consent was given during sex or after sex. Sometimes consent was non-verbal, usually during sex. Other times, consent was assumed based on prior conversations, because they has done it before, the person’s interest in choking, or because it was assumed to be part of regular sex. Keep in mind that this happened among college students and not in the BDSM community, which has a strong consent culture. The students also considered choking to be safer than other forms of kinky sexy, an attitude that has been encouraged by the media (Herbenick et al., 2023). My survey in Fetlife I did my own inquiry into this by posting an article in Fetlife titled What Do You Like About Being Choked? It said: I heard some people say that being choked puts them in an altered state of consciousness that is different from sub space or from the effect of any drug. Is it true? In your experience, does choking make orgasms more intense? Or do you like choking for the psychological feeling that it brings you? Like, for example, surrender? Or perhaps you like the feeling of losing consciousness? Or is it a feeling of euphoria? Or is it something else? I think Fetlife was a good choice because I wanted to query specifically people who are into BDSM, and not those who practice choking as part of sex. However, the answers need to be interpreted in that context. I got 12 responses, 10 from women, 2 from non-binary persons and none from men. Four responders defined themselves as submissive, one as a slave, three as a masochist, one as a little, and the other three as exploring or curious. The following reasons were given to enjoy choking: Surrender (9 responders): loss of control, feeling helpless and vulnerable, feeling the power of the dominant, giving power to the dominant. Fear (5 responders), including feeling challenged and overcoming panic. Trust (4 responders): feeling that they could trust their safety to the choker. Euphoria (4 responders), including feeling high, lightheaded and physical pleasure. Orgasm and sensations are more intense (4 responders). Feeling safe, centered, calm (3 responders) despite the risk. Unconsciousness (3 responders). Edging to orgasm (2 responders). The most common responses align with the feelings usually sought in other BDSM activities: surrender to the power of the dominant, and the interplay between fear and feeling safe by trusting the top. But choking was also a source of pleasure. It produced euphoria and a high consisting of lightheadedness and physical pleasure. It also intensified physical sensations, including orgasm. Last, three people reported a paradoxical feeling of safety and calm, despite the obvious risk of the activity. My findings are consistent with one of the papers by the group of Debbie Herbenick (Herbenick et al., 2022a), a qualitative survey about the reasons why women like to be choked. In it, no participants reported actually losing consciousness. But many mentioned being excited about surrendering, empowering their partner, enhanced sexual arousal and longer orgasms. Fear and danger made the sex more exciting and pleasurable. Are the effects of choking similar to those of nitrous oxide? I was surprised not to find any mention to drug-like altered states of consciousness, which I heard about in some comments to my articles in Fetlife. When I asked if the feeling of being choked resembled the effect of any drug, one person responded that it did not feel like the effect of cannabis or psychedelics, but it could be similar to that of nitrous oxide, also known as laughing gas and whippets. Whippets are obtained as canisters to make whipped cream (Srichawla, 2022). They produce a severe deficiency in vitamin B12 (Maheshwari and Athiraman, 2022) and serious neurological effects. They are consumed because they produce euphoria, analgesia and a brief high. The mechanism of action of nitrous oxide is still unclear. It acts on many neurotransmitter receptors, blocking excitatory NMDA receptors and nicotinic acetylcholine receptors and potentiating inhibitory GABA and glycine receptors. Perhaps the brain hypoxia produced by choking has similar effects. Indeed, inhaling nitrous oxide as whippets produces hypoxia. References Herbenick D, Guerra-Reyes L, Patterson C, Rosenstock Gonzalez YR, Wagner C, Zounlome N (2022a) "It Was Scary, But Then It Was Kind of Exciting": Young Women's Experiences with Choking During Sex. Arch Sex Behav 51:1103-1123. Herbenick D, Patterson C, Khan S, Voorheis E, Sullivan A, Wright P, Keene S (2023) "Don't Just Randomly Grab Someone's Neck during Intercourse!" An Analysis of Internet Articles about Choking/Strangulation during Sex. J Sex Marital Ther 49:41-55. Herbenick D, Patterson C, Beckmeyer J, Gonzalez YRR, Luetke M, Guerra-Reyes L, Eastman-Mueller H, Valdivia DS, Rosenberg M (2021) Diverse Sexual Behaviors in Undergraduate Students: Findings From a Campus Probability Survey. The journal of sexual medicine 18:1024-1041. Herbenick D, Fu TC, Eastman-Mueller H, Thomas S, Svetina Valdivia D, Rosenberg M, Guerra-Reyes L, Wright PJ, Kawata K, Feiner JR (2022b) Frequency, Method, Intensity, and Health Sequelae of Sexual Choking Among U.S. Undergraduate and Graduate Students. Arch Sex Behav. Maheshwari M, Athiraman H (2022) Whippets Causing Vitamin B12 Deficiency. Cureus 14:e23148. Srichawla BS (2022) Nitrous Oxide/Whippits-Induced Thoracic Spinal Cord Myelopathy and Cognitive Decline With Normal Serum Vitamin B₁₂. Cureus 14:e24581. Copyright 2023 Hermes Solenzol.

Choking is the main cause of death in BDSM, but less common than it is thought I strongly recommend not to practice choking. This article is part of a series intended to show that choking is unsafe, may cause brain damage, and is potentially lethal. Deaths by autoerotic asphyxiation Choking appears in the popular imagination as a deathly activity, largely because of the many celebrities that have died of autoerotic asphyxiation. However, it is important to distinguish between breath play practiced in solitary and that practiced in couples. In the former, loss of consciousness or control over the body can lead to dead because the person cannot escape the asphyxia, while in the latter the person doing the choking has some control over the process. But even the number of deaths produced by autoerotic (i.e. solitary) asphyxiation has been exaggerated. It is often mentioned that it causes “500 to 1000 deaths per year in the United States and Canada” (Sauvageau, 2012), but that number is an estimation based on unpublished data. An epidemiological study based on 38 autoerotic deaths in Alberta, Canada, gave a lower number: 0.56 deaths per million inhabitants per year (Sauvageau, 2012). Multiplying this number by the population of the United States, 333 million, gives us an estimate of 186 deaths per year caused by autoerotic asphyxiation. The number of autoerotic deaths per million inhabitants per year is similar in other developed countries: 0.3 in Australia, 0.14 in Sweden and 0.5 in Germany. Choking deaths in BDSM Another paper (Schori et al., 2022) inquired specifically about deaths involved in BDSM play. Doing a literature search, they identified 17 deaths produced by BDSM activities. Of those, all were caused by asphyxia except one case, in which death was caused by hemorrhage due to inserting an inflatable balloon and other objects in the vagina. One death by asphyxia was caused by blocking the mouth and the nose with tape and fingers. The remaining 15 deaths were by strangulation, 5 with the hand or the forearm and 10 with ligatures (rope, belt, collar or chain). One of the cases of strangulation was a shibari scene in which two women were hanged with the same rope suspended from the ceiling (Roma et al., 2013). When one of them lost consciousness, her weight hanged the other. The first ended up death and the second, in a coma. The rate of death was similar across genders: 9 men and 8 women. In 9 of the cases, both partners were experienced in BDSM. In 2 cases, the top was a professional dominatrix. In 3 cases, the participants had discussed breath play techniques and cardiopulmonary resuscitation (CPR). Therefore, experience and education were not enough to prevent the deaths. Conclusions The conclusions are a mixed bag. On the one hand, fatalities caused by BDSM are rare: 15 occurred in the United States from 1986 to 2020, and 3 in Germany from 1993 to 2017. On the other hand, breath play caused a disproportionate number of the deaths in BDSM. It is fair to say that, by far, choking is the most deathly BDSM activity. But dying is only the worst thing that can happen during breath play. There may be other health consequences, including brain damage. These are much harder to assess. I will discuss that in future articles. References Roma P, Pazzelli F, Pompili M, Girardi P, Ferracuti S (2013) Shibari: double hanging during consensual sexual asphyxia. Arch Sex Behav 42:895-900. Sauvageau A (2012) Autoerotic deaths: a 25-year retrospective epidemiological study. Am J Forensic Med Pathol 33:143-146. Schori A, Jackowski C, Schön CA (2022) How safe is BDSM? A literature review on fatal outcome in BDSM play. International Journal of Legal Medicine 136:287-295. Copyright 2023 Hermes Solenzol.

The two main practices to induce asphyxia for pleasure I strongly recommend not to practice choking. This article is part of a series intended to show that choking is unsafe, may cause brain damage, and is potentially lethal. Choking, as it is used during sex or in BDSM, aims to deprive the brain of oxygen to induce mental changes that are pleasurable, either by themselves or because they intensify sexual sensations. This can be done in two ways: by interrupting the air flow into the lungs (“air choke”) or by interrupting the blood supply to the brain (“blood choke”). This terminology comes from martial arts. There is some debate in the BDSM community about which one is better. The air choke Still, most of the choking during sex is done by squeezing the throat with one hand (Herbenick et al., 2022). It is hard to say if this is an air choke or a blood choke. If pressure is applied to the front of the neck, this can close the trachea, producing an air choke. However, applying pressure to the trachea is unpleasant and dangerous, because it can damage the vocal cords, impairing speech. It can also damage the thyroid gland or the trachea itself, which can have serious health effects. The trachea is a very delicate structure made of cartilage, a tissue similar to bone that also makes our joints. This makes the trachea semi-rigid, so applying pressure on it can deform it permanently. Therefore, this form of choking can produce long-term damage affecting breathing, talking and swallowing. A crushed trachea is life-threatening. You can kill somebody this way. Another straightforward way to produce an air choke is to block the nose and the mouth with the hand. A person can easily get out of this choke by struggling, which can be both a problem - involuntary struggling can stop the choke - and an advantage - a built-in safety feature. Deep throating - inserting the penis into the mouth deep enough to block air passage into the larynx - can be a form of choking. However, the gagging reflex would be induced much sooner than air deprivation is felt. Besides, a panicking bottom can bite the cock that is gagging him or her. Using a pillow or a mask to block breathing is dangerous because the top cannot see the face of the bottom, and therefore cannot judge the level of asphyxiation. This could be prevented by using a transparent bag, but removing it takes too long. Still too dangerous. Some people use a sharp object to quickly puncture the bag, but this risks cutting the face of the person being choked. The blood choke (carotid occlusion) The blood choke consists of stopping the blood supply to the brain by blocking the carotid arteries. They run superficially on both sides of the neck and can be blocked by applying a small amount of pressure on the right spots. On purpose or by accident, this is probably what it is done in some of the one-hand chokes that are more prevalent, according to the surveys. A common chokehold in martial arts consists in wrapping the neck of the adversary with one arm from behind, in a position resembling the number 4. This compresses the carotid arteries and jugular veins, but not the trachea, cutting the blood flow to the brain and thus inducing unconsciousness in 10-20 seconds. However, using this chokehold during sex of BDSM play has the problem that the person applying the choke cannot see the face of the person being choked, and therefore cannot regulate the pressure and the timing to avoid going too far. Unlike in martial arts and self-defense, most people that use choking during sex do not want to induce unconsciousness. Neither should they, since loss of consciousness by anoxia often leads to brain damage. Hence, the most common way to induce a blood choke during sex is to apply pressure to the sides of the neck with one hand, while looking into the face of the person being choked to evaluate their response. Which one is safer? Some people in the BDSM community argue that the blood choke is safer than the air choke for the following reasons: It affects only the brain and not the rest of the body. The blood flow can be manipulated quickly and subtly by changing the pressure of the hand. Changes in consciousness can be induced and restore quickly. It avoids damaging the trachea and other delicate structures in the neck. It does not increase the CO2 levels of the blood and hence blood acidity, like the air choke does. However, the blood choke has dangers that are not obvious at first sight. But understanding these dangers requires some complicated explanations about the functioning of the brain and cardiovascular physiology, which I will give in the next articles. For now, let me just say that the blood choke is, in fact, more dangerous than the air choke. Previous articles in this series https://www.hermessolenzol.com/en/post/how-common-is-sexual-choking https://www.hermessolenzol.com/en/post/why-do-people-enjoy-being-choked https://www.hermessolenzol.com/en/post/how-deathly-is-choking

Dying is not the only danger of choking I strongly recommend not to practice choking. This article is part of a series intended to show that choking is unsafe, may cause brain damage, and is potentially lethal. What happens when the brain lacks oxygen? To stay conscious and alive, our brain needs a continuous supply of oxygen and glucose from the blood. Neurons are the most finicky cells of the body. If they don’t get their oxygen, they throw a tantrum and die. Tantrum is quite an appropriate metaphor, because a neuron that is starving for oxygen begins firing a lot of action potentials and releasing its neurotransmitters. The main excitatory neurotransmitter in the brain is the amino acid glutamate, which is also an abundant metabolite. When a neuron dies, all of its glutamate is released into its surrounding medium, activating glutamate receptors in its nearby neurons. Too much activation of glutamate receptors kills those neurons, too, setting off a chain reaction that produces a wave of cell death spreading through the brain. This glutamate release is what produces brain damage during a stroke. A stroke happens when a capillary inside the brain is blocked by a blood clot. Neurons that were supplied with oxygen by that capillary die, releasing glutamate and starting this wave of death. So, why doesn’t it end up killing the whole brain? Because there are cells in the brain, the glia, that are in charge of preventing damage by absorbing glutamate and other neurotoxic substances. Still, considerable harm can be done before these cells manage to bring the situation under control. Once neurons die, the body cannot replace them. The carotid arteries detect blood pressure Oxygenated blood is supplied to the brain through the carotid arteries, situated on the sides of the neck, towards the front. Just above the thyroid cartilage, or Adam’s apple, the carotid arteries split into the external carotid, which supplies blood to the face, and the internal carotid, which supplies blood to the brain. This bifurcation of the carotid artery is very important because it forms the carotid sinus, a swelling of the internal carotid artery. The carotid sinus is one of the two places in the circulatory system where there are baroreceptors. The other place is the aortic arch, situated in the aorta artery just above the heart. Baroreceptors are sensory neurons is charge of detecting blood pressure. They send this information to the brain so it can adjust the beating of the heart and the dilation of the capillaries. The carotid sinus sends blood pressure information to the brain through the glossopharyngeal nerve, while the aortic arch sends it through the vagus nerve. Both nerves end in the same place: the nucleus of the solitary tract or solitary nucleus, in the medulla oblongata. The solitary nucleus modulates the activity of the sympathetic and parasympathetic systems through the hypothalamus. Among other things, this modulates the heartbeat and the dilation of the capillaries, forming a feedback loop that controls blood pressure. Problems with the blood choke In a previous article, I explained that an air choke is blocking the entrance of air into the lungs, while a blood choke is blocking the carotid arteries and the jugular veins to interrupt the blood supply of the brain. The information above is crucial to understand the problems with the blood choke. In an air choke, a person can survive for several minutes without breathing. The air that remains in the lungs and the oxygen stored in the blood's hemoglobin and the muscles’ myoglobin can supply the organs, including the brain, for some time. Free-divers can hold their breath and remain conscious for several minutes, even while swimming vigorously in cold water (Scott et al., 2021). Interrupting the oxygen supply to the brain is an entirely different matter. Unconsciousness takes place in 10 to 20 seconds, irreversible neurological damage before one minute, and death soon afterwards. Therefore, a blood choke has to be timed precisely to avoid brain damage and death. But even if a blood choke is done for a time short enough for survival, there are other problems involved. It compresses or blocks the carotid arteries, which supply blood to the brain, and the jugular veins, which are the exit route of blood from the brain. This decreases blood flow (cerebral ischemia) and therefore the supply of glucose and oxygen (cerebral hypoxia). This represents a big problem for the brain, as shown by the damage caused by stroke. Except that, with a blood choke, we are altering the blood supply to the entire brain and not just a small part of it. Some neurons may be more sensitive to hypoxia than others, resulting in localized trauma that is hard to detect. Reperfusion injury Another problem is reperfusion injury, the harm produced when blood suddenly enters a tissue that has been deprived of it. Reperfusion increases the production of reactive oxygen molecules from the sudden increase in oxygen, as well as cytokines and chemokines, which are pro-inflammatory molecules produced by immune cells and microglia (Kalogeris et al., 2012). All this is extremely damaging to nervous tissue. The vasovagal response Yet another problem arises from the fact that the carotid sinus contains the baroreceptors that control blood pressure in the entire body. A blood choke changes the pressure detected by these baroreceptors. Pressure on the neck above the trachea would be exerted directly on the carotid sinuses, stimulating the baroreceptors. Pressure lower on the neck would decrease the blood reaching the carotid sinus, making it detect a lower blood pressure. The error signal thus produced in the carotid sinus would affect the beating of the heart, usually decreasing it. A highly controversial issue among pathologists is whether this could stop the heart altogether. This could explain why some deaths by strangulation occurred even though the choke did not last long enough to produce brain damage. The vasovagal response or reflex syncope “is a brief loss of consciousness due to a neurologically induced drop in blood pressure. Before the person passes out there may be sweating, a decreased ability to see, or ringing in the ears. […] Carotid sinus syncope is due to pressure on the carotid sinus in the neck. The underlying mechanism involves the nervous system slowing the heart rate and dilating blood vessels resulting in low blood pressure and therefore not enough blood flow to the brain.” Wikipedia. Other problems with the blood choke Messing with the blood pressure sensing by the baroreceptors in the carotid sinuses also affects the sympathetic and parasympathetic nervous systems, explaining why choking can produce reactions like nausea and vomiting. The whole body is thrown out of balance. There may be other complications of carotid occlusion, like cholesterol plaques being released from inside the carotids to cause strokes in the brain. Carotid occlusion is much more dangerous than other forms of asphyxiation. The key fact is that when you hold your breath, or when somebody blocks your breathing, there is a big reservoir of oxygen that your body can use to stay alive. However, your brain cannot store oxygen. When you block the carotids, your brain starts to run out of oxygen right away. Is there a risk of cumulative brain damage? Even if it does not cause death, repeated choking to the point of unconsciousness may have cumulative effects, leading to brain damage. Neuronal death may happen without any symptoms because the brain is very good at compensating for loss of function. You don’t know what is going on in your brain when you drive it close to unconsciousness, just because it’s so much fun! Your neurons could be dying while you party. This is what happened with traumatic brain injury (TBI), which is now called a “silent epidemic” (Alkhaibary et al., 2021). Sports like boxing and football cause repeated concussions that have an additive effect. When TBI finally manifests itself, it is too late to do anything about it. TBI is different from one person to another because different brain regions are affected. It produces sensory hypersensitivity, chronic pain, motor problems, memory loss and cognitive decline. While TBI and brain anoxia may seem different, they both involve neuronal death, so they may produce similar symptoms. Recreational choking may lead to another silent epidemic that would remain unknown for many years because the symptoms take a long time to appear and their cause may not be apparent at first. But, is there any evidence of this? Or is it just speculation and fearmongering? In the next article of this series, I will present evidence that repetitive choking leads to cognitive deficits and psychological problems. References Alkhaibary A, Alshalawi A, Althaqafi RMM, Alghuraybi AA, Basalamah A, Shammaa AM, Altalhy AA, Abdelrahman TM (2021) Traumatic Brain Injury: A Perspective on the Silent Epidemic. Cureus 13:e15318. Kalogeris T, Baines CP, Krenz M, Korthuis RJ (2012) Cell biology of ischemia/reperfusion injury. Int Rev Cell Mol Biol 298:229-317. Scott T, van Waart H, Vrijdag XCE, Mullins D, Mesley P, Mitchell SJ (2021) Arterial blood gas measurements during deep open-water breath-hold dives. J Appl Physiol (1985) 130:1490-1495. Copyright 2023 Hermes Solenzol.

Scientific studies show that women who are choked have more psychological problems and changes in brain connectivity I strongly recommend not to practice choking. This article is part of a series intended to show that choking is unsafe, may cause brain damage, and is potentially lethal. Health problems in women who have been choked during sex Even serious brain injury can go undetected because the brain is very good at hiding it. Hence, there have been studies aiming to determine if women who had been choked showed signs of brain injury. Women who had been choked during sex more than five times in the last month were more likely to feel sad, lonely, anxious and depressed than women who had never been choked (Herbenick et al., 2022). “Women with a history of being choked more than five times during sex within the past 30 days were 2.19 times as likely to endorse experiencing overwhelming anxiety, 2.16 times more likely to report feeling very sad, 1.59 times more likely to report being very lonely, and 1.77 times more likely to feel ‘so depressed that it was difficult to function’ than women who had never been choked.” (Huibregtse et al., 2022). Women who had been choked during intimate partner violence There are also detailed studies of psychological and cognitive problems in women who had been choked during intimate partner violence. One of them (Valera et al., 2022) found that these women showed deficits in long-term memory, had higher levels of depression and presented symptoms of posttraumatic stress. However, some of these problems may derive from the psychological trauma produced by the assault and not from the strangulation itself. A review of 30 papers about strangulation during domestic and sexual violence (Bichard et al., 2022) showed that the victims presented the following problems: Pathological: tears in the arterial wall and stroke. Neurological: loss of consciousness, seizures, motor and speech disorders and paralysis. Psychological: posttraumatic stress, depression, suicidal ideation and dissociation. Cognitive: memory loss. Behavioral: aggression, compliance with the aggressor and lack of help-seeking. Obviously, strangulation during violence is much more severe than that occurring during consensual sex and BDSM. Still, its consequences show what can happen if choking is taken too far. In particular, loss of consciousness should be considered a sign that choking is extreme enough to produce brain injury. Brain imaging studies in women who had been choked during sex But, is there evidence that choking during sex produces brain damage? I found two studies that did this using brain imaging (fMRI) and tests of brain function. One study (Hou et al., 2022) compared 21 women who had never been choked with 20 women who had been choked four times or more during the last month, using fMRI to measure the functioning of the cortex and brain connectivity. The paper reports that women who had been choked showed an imbalance in neural activation between the brain hemispheres. They also showed higher than normal connectivity between the angular gyrus and brain regions involved in motor control, emotion and consciousness. The angular gyrus is involved in comprehension while reading, number processing, spatial cognition, memory retrieval and attention. It is hard to tell what these increases in connectivity mean, or even if they are caused by the choking. Another study (Huibregtse et al., 2022) used a similar sample: 20 women who had been choked at least four times during the last month and 20 women who had never been choked. Their brains were imaged using fMRI while they did verbal and visual tasks to measure their working memory. Both groups of women performed equally well in these tasks. However, the fMRI revealed that, during the verbal memory task, women in the choked group showing increased activation of their corpus callosum, left posterior thalamic radiation, left caudate nucleus and left insula. The corpus callosum is the bundle of fivers that connect the brain hemispheres. The thalamus is the sensory relay in the middle of the brain. The caudate nucleus is part of the striatum and reward system, and is involved in motor control and learning. The insula processes the emotions associated with pain and pleasure, and other emotions. During the visual memory task, women in the choked group showed more activation of the superior and right middle frontal gyri. As the difficulty of the task increased, the choked group showed less activation of the middle and the right inferior frontal gyri. The frontal gyri are involved in involved in self-awareness, decision-making and impulse control. They are also critical for working memory. The authors of the study concluded that, although the women who had been choked did not show a decreased ability in the working memory tasks, they had to allocate increased resources to the parts of their brain involved in performing these tasks. This could indicate hypoxic or ischemic damage or reperfusion injury produced by the repeated choking. Or there could be a remodeling of brain networks. These two studies show that there are definite differences between the brains of choked women and women who had never been choked. These differences appear minor, but they could signal a build-up of brain trauma. Keep in mind that the women in these studies were young college students. Older brains might show more problems after choking. Is choking worth the risks? I don’t think choking for fun is worth the risks. There many other ways to have fun with sex and BDSM that are much safer. I consider choking unsafe and I advise against doing it. If you put together everything I wrote in this series of articles, you will realize that there are no safe ways to practice choking safely. The analyses of cases of death from choking show that there is a low but significant risk of death that cannot be mitigated by any amount of knowledge and safety precautions. Recoveries from cardiac arrest are much rarer than what movies make us think they are. Even if nobody dies, repetitive choking can induce cumulative brain damage. Especially if choking induces loss of consciousness. This article presents evidence that cognitive and psychological deficits occur in people who are frequently choked. Some people may just like to put a hand on the throat and do some pretend choking. As long as there is no blockade of blood flow to the brain or air entry to the lungs, this is fine. But you should not call it choking, because that normalizes choking for other people. The safety of choking is still hotly debated in the BDSM community. However, most BDSM organizations and clubs do not allow choking in their facilities. Sex adviser Dan Savage advises against it in The Savage Lovecast, where he has interviewed professor Debbie Herbenick, the author of many of the papers I have cited here. In the end, whether to choke or not is a risk that should be assumed by the individuals involved, with full consent and plenty of information. However, as we have seen, both things are often lacking when it comes to choking. To be fully informed on this matter requires some in-depth knowledge of physiology and neuroscience. Weighing pleasure, on the one hand, against a real possibility of brain damage and death, on the other, the decision seems quite obvious to me. But I also think it’s important that we continue having a conversation about this issue. If people are going to do it, we need to continue to evaluate its risks and disseminate information about the safest way to do it. References Bichard H, Byrne C, Saville CWN, Coetzer R (2022) The neuropsychological outcomes of non-fatal strangulation in domestic and sexual violence: A systematic review. Neuropsychol Rehabil 32:1164-1192. Herbenick D, Fu TC, Kawata K, Eastman-Mueller H, Guerra-Reyes L, Rosenberg M, Valdivia DS (2022) Non-Fatal Strangulation/Choking During Sex and Its Associations with Mental Health: Findings from an Undergraduate Probability Survey. J Sex Marital Ther 48:238-250. Hou J, Huibregtse ME, Alexander IL, Klemsz LM, Fu TC, Fortenberry JD, Herbenick D, Kawata K (2022) Association of frequent sexual choking/strangulation with neurophysiological responses: a pilot resting-state fMRI study. J Neurotrauma 40:1339-1351. Huibregtse ME, Alexander IL, Klemsz LM, Fu TC, Fortenberry JD, Herbenick D, Kawata K (2022) Frequent and Recent Non-fatal Strangulation/Choking During Sex and Its Association With fMRI Activation During Working Memory Tasks. Frontiers in behavioral neuroscience 16:881678. Valera EM, Daugherty JC, Scott OC, Berenbaum H (2022) Strangulation as an Acquired Brain Injury in Intimate-Partner Violence and Its Relationship to Cognitive and Psychological Functioning: A Preliminary Study. J Head Trauma Rehabil 37:15-23. Copyright 2023 Hermes Solenzol.

When I look at the amazing description of the Universe created by science, I find that it is all full of meaning I would define “meaning” as something larger than ourselves that gives a sense of purpose and direction to our lives. Having meaning in life is one of the key ingredients of happiness, because for most people a life worth living needs to have purpose in a larger context. Meaning and ethics Meaning is also important as a foundation for ethics. Systems of values can be reduced to a few fundamental premises from which codes of ethics can be developed rationally. However, those premises themselves are arbitrary unless they can be referred to some other knowledge, like an understanding of what it means to be human, or a description of the world. For example, Christianity and Islam base their ethics on the will of God. This is based on the belief that God created the Universe and His will takes priority over anything else. However, this system of ethics falls apart when we question the belief in God, or the morality of submitting to the will of a God that allows suffering. In Utilitarianism, ethics are based on maximizing happiness and minimizing suffering. This is based on the belief that being happy and avoiding suffering is the ultimate objective of our lives. Similarly, Buddhism makes its ultimate goal the overcoming of suffering by understanding our innermost nature. However, being happy and overcoming suffering look like rather short-sighted goals. We are left wondering: isn’t there anything more to life? Nihilism The belief that life is devoid of meaning is called nihilism. According to this view, being happy and avoiding suffering are spurious goals that are themselves devoid of meaning. Therefore, establishing any foundation for ethics on them is also futile. Many people reject nihilism because it leads to a cynical outlook on life in which nothing that we do ultimately makes sense. It leads to its own kind of suffering: the existential angst of believing that our life has no purpose. A humorous example of the nihilistic and cynical outlook that some people derive from science can be found in The Universe Song, by Monty Python, featured in their movie The Meaning of Life. Existentialism Existentialism says that the only place we can find meaning is in our own lives and in human enterprises. That is, meaning is to be found inside, not outside ourselves. Today this is has become the common belief of most people who reject religion and adopt a value system based on science and rationality. Our cooperative nature, empathy and sense of solidarity make it meaningful for us to strive to improve the lot of our fellow humans. In politics, socialism makes the attaining of an egalitarian and free society a goal that provides meaning to our lives. Indeed, a utopian society is a goal larger than ourselves, so it can provide purpose and direction to our lives. Problems with existentialism However, there are some problems with defining all ethics exclusively on the basis of human happiness and suffering. Take environmentalism, for example. It can be argued that a good environment is good for humans, so we should strive to improve it. Nevertheless, humans could be perfectly happy if an obscure species of insect or plant goes extinct. And yet our intuition tells us that extinguishing species is wrong and should be avoided, even at a relatively high cost. Environmental laws in the USA and most developed countries are based on that principle. Another example is science. It is common to argue that scientific research is valuable because it will bring cures for diseases and new devices that would make us happier. But if this was true, then we should stop expending enormous amounts of money sending probes to explore the Solar System and beyond, or doing research on particle physics, because those enterprises don’t do much to cure our suffering or to make us happy. Every scientist secretly knows that we do science primarily for the sake of knowledge itself, not for its application. In fact, scientific knowledge often brings good and bad things: nuclear power and atomic bombs; pharmaceuticals and environmental poisons; the internet and its ability to control our minds; gene therapy and genetic manipulation. For every blessing there is a curse. No wonder that some people feel that we should retreat to a simple, agrarian society without science and technology, or even to being the hunter-gatherers that we were before the Agrarian Revolution. Some even think the world would be better off without any humans at all. What I am going to argue here is that meaning can be found not just inside us, but also outside in the Universe. Furthermore, this idea is based on scientific knowledge and not on religious belief. The evolution of everything If we take a step back and look at what science has shown, we see that the Universe is not a series of random processes. It has been evolving since the Big Bang in a definite direction: an increase in complexity and organization. And this can even be formalized scientifically: the amount of information that we need to describe the Universe has increased over time. In the beginning, there were just basic particles: photons, electrons, protons, neutrinos, etc. When the Universe cooled enough, electrons and protons got organized into hydrogen atoms. Stars got formed by gravity, and hydrogen turned into helium inside them. Then, as the star aged, hydrogen turned into carbon and the other light atoms of the Periodic Table. Stars exploded into novas and supernovas and collapsed into neutron stars, given birth to the heavier atoms. This stardust floating in space forming nebulae eventually gives to new stars, which now had planets where this new zoo of atoms is collected. On Earth, carbon, hydrogen, nitrogen, oxygen and a few other atoms organized themselves into living beings. Evolution started, creating more and more life forms. While it is true that evolution does not proceed in any particular direction, it is also true that the algorithm of genetic mutation plus natural selection acts to fill every ecological niche by creating beings of every possible size and shape (Stuart Kaufman, At Home in the Universe). This generates simple life forms, but also large, complex animals. One of them is the human being. Human’s ace-in-the-hole to win the natural selection game is having a large brain that allows cooperative behavior based on the transfer of information, not only in the present by also across time, from generation to generation. Just like life once appeared, culture shows up as something entirely new. One form of culture is science, with all its wonderful tools to extract and organize information about everything. We become the eyes by which the Universe sees itself. Among other things, we now know that the Sun is not unique in having planets capable of evolving life. Hence, the same process of evolution: random search for new forms and the eventual appearance of intelligence could have happened elsewhere. Everywhere! Billions of stars playing at the roulette of life and intelligence. How many winners? Probably a lot. The hierarchy of being When we look at this whole process we realize that it is organized in the form of a nested hierarchy. By that, I mean that there are several discrete levels of complexity, each one built upon the lower one: physics, chemistry, biology, neuroscience, psychology, sociology. We have a different science to study each level. This is not by caprice, but because each level has its own rules that have to be studied separately and cannot be deduced from the rules of the lower level (Ray Kurzweil, The Singularity Is Near: When Humans Transcend Biology). This is called emergence: the fact that new laws appear at a certain point in time, which coexist with the laws of the lower level but constitute entirely new phenomena. Thus, the laws of chemistry add novelty to the laws of particle physics. And when life appears, it follows laws that are quite different from the laws of chemistry. And on and on to the laws that govern nervous systems and those that rule human interactions. What causes emergence? In one view, evolution and other processes that create complexity and self-organization are algorithms: information processing events that follow certain rules of computation to generate an outcome from original conditions (Charles Seife, Decoding the Universe; Seth Lloyd, Programming the Universe). For example, the algorithm of evolution is: generate mutations in the DNA; output them in the phenotype; test phenotype against the environment; IF death, discard the mutation; IF survival, amplify the mutation by reproducing; Go to step 1 while producing offspring. This algorithm explores a landscape of all possible shapes of living beings, while natural selection eliminates shapes that are not fit for the environment (Stuart Kaufman, At Home in the Universe, Investigations). In fact, the algorithm is itself the product of early evolution and natural selection. Mutation is not random, as previously suspected, but perfected by natural selection so that some parts to the DNA are more susceptible for mutation than others and there are specific mechanisms to generate genetic variation (Lynn Helena Caporale, Darwin in the Genome). A meaningful Universe? What does all this have to do with finding meaning in our lives? Well, we intuitively value the complexity and self-organization that we see in living beings. We have the same admiration for intelligence and culture, which we see as one step above mere life. The fact that the Universe has steadily moved to create life and then ourselves indicates that we are part of a process much larger than ourselves, something truly awe-inspiring. So it is not just that we are working for the good of Humanity while Humanity in itself has no meaning. Humanity does have meaning because it is part of a larger process encompassing the whole history of the Universe. Will this process continue in the future, beyond Humanity? Here it is tempting to fall into the heresy of teleology, which is saying that evolution has a particular goal, like producing human beings, or that the Universe has a goal, like producing consciousness or intelligence. This idea has been condemned because goals are something that humans have, not inanimate matter. However, as I argue in another article, agency (doing something to achieve a particular outcome) could be considered a property of living beings. And, looking at the past, it is unavoidable to conclude that the Universe has evolved in the direction of increasing complexity and self-organization and that this has led to the appearance of information-rich organisms and intelligence. Transhumanism Indeed, what we are doing right now is creating computers that store all our cultural information and also generate information in increasingly larger amounts. Is that the next step of the universal evolution? Are we going to continue to be part of the process, or will we be left behind? Transhumanism is a modern philosophy that, based on this view of the Cosmos, proposes that we can find meaning in the future development of the human race. It hopes that we will walk hand-in-hand with computers instead of being replaced by them (Ray Kurzweil, The Singularity Is Near: When Humans Transcend Biology). We may be able to do that by linking our brains directly to a computer, perhaps eventually migrating our entire consciousness into a computer. Conclusions It is not that the Universe has meaning in itself. Is that we are able to find meaning when we contemplate how the Universe has been evolving to give rise to consciousness, intelligence and culture. We humans are the ones who can assign value and beauty to things outside ourselves. We look at a crashing wave, at a snow-crested mountain, at a dolphin, and find those things beautiful. Likewise, we consider how stars smash atoms together, how planets are created from clouds of interstellar gas, how life arises and evolves, how consciousness emerges from complex nervous systems, and we are filled with awe. We do not exist independently of the Cosmos, we are stardust that has gained consciousness. What we do in our lives, the destiny of Humanity, matters because it is part of this amazing cosmic play. We do not know where the Universe will go from here, but somehow we suspect it will very much be worth the ride.

The beauty of dating an amputee I have to confess that the first time I saw her stump I felt a bit disgusted. The skin was loose and wrinkled, full of scars. It was kind of soft to the touch and it had a peculiar smell, maybe because of all that time inside the rubber envelop of her orthopedic leg. We made love, anyway. Erin, despite having her left leg amputated just below the knee, is a beautiful and sexy woman. She has the willowy body of a teenager, well-defined muscles in her arms, shoulders and back, a flat belly, small delicious breasts and an exquisite ass - as can be seen in this picture I took while she was sleeping. Soon enough, I became aware that Erin is an expert in the erotic arts. Her desire gets easily turned on and then she gives herself entirely to you, to everything you want to do to her, opening her body with a fiery enthusiasm, without fears or traumas. We rolled in bed testing every position, every perversion, our naked bodies covered by a sheen of sweat, not knowing if it was hers or mine. As a prerequisite for our relationship, I required of her the most rigorous honesty: I can’t stand lies, and I hold secrets only when strictly necessary. So the following day I didn’t want to hide what I had felt. “I had some trouble with your stump”, I confessed. Her answer was totally unexpected: “And you think I don’t? It’s been more than twenty years since I lost my leg and I still haven’t gotten used to it”. That moved me. If I didn’t like her stump I always had the option of leaving her. But she didn’t. She always would have to make love putting just one foot up in the air, trying not to look at her stump, hoping that the lover of the occasion wasn’t bothered too much by her incomplete body. I think it was then when I started falling in love with Erin. Little by little, in subsequent dates, Erin told me her story. When she was a teenager she loved to run. She would spend hours jogging between the houses of Burbank, just at the foot of the steep San Gabriel mountains that mark the horizon of Los Angeles. She ran marathons and even won a few medals. She had beautiful legs, strong and slender. Once, when she needed money, she signed up to show them off in a strip-tease show, and they were a big hit. She was twenty five when disaster stroke. At sunset, on a fine September day, a friend asked her to take her home in her scooter. A car appeared out of nowhere, making an illegal left turn, and slammed into them. Erin found herself lying on the street with her left foot torn apart, spitting her teeth on the asphalt. Her friend came out of the accident unscathed. Erin spent several months in the hospital, until Christmas. The doctors did everything they could to save her foot, but to no avail. Erin told her mother that she’d rather die than to let them cut away her leg. She couldn’t live without being able to run. In the end, it was the stench of the gangrene that changed her mind: an odor indescribably foul that was with her night and day. She thought she was going crazy, particularly knowing that it came from her own body. One day the doctor came into her room and looked at her without saying anything. “It has to go, doesn’t it?”, said Erin. The doctor nodded. But that was not the end of it. Even after the amputation, the gangrene continued to spread. The doctors had to cut her leg over and over again, every time a bit higher, getting closer to the knee. Her fibula had to be completely extirpated and only a little piece remained of her tibia. To cover her stump, they had to remove skin from the front of her thighs, leaving two rectangular patches of whitish skin that resemble the mended pants of a beggar. One day, joking, I told her that she looked like a scarecrow. For a while, she signed her e-mails “scarecrow”. Erin had no money to buy an orthopedic leg, so she made herself a wooden leg, like a pirate’s leg, that she tied to her stump with leather straps. Her workmates gave her stickers and tags that she placed over the wooden leg until it was completely covered. Now she has a nice orthopedic leg that allows her to walk normally. One day we went to the beach and I convinced her to run with me at the edge of the surf. Yes, Erin can still run, but she doesn’t do it unless necessary because the repeated impact can crack the plastic of her orthopedic leg, and she doesn’t have enough money to replace it. I never thought that I would end up with a lover with a broken body. I never thought I would come to like her so much. What is beauty, in the end? There is a beauty that is easy to see, the one that they instill in you in movies, magazines and advertisement. The soft, unblemished skin. The symmetrical body. The shapely muscles with that thin layer of fat that soften the corners of the female body. That type of beauty is just an animal reflex; in the end everything comes to attraction to whatever reveals health and revulsion to whatever indicates disease. But there is another type of beauty that is exclusively human: the beauty of acting the right way, of living an ethical life. The beauty of a story that touches something deep inside you. That’s what I see in the mutilated body of Erin: her story, the courage that she summoned to face never been able to run again, having to spend the rest of her life dragging a leg made of plastic and steel. Now, when we make love I kiss her scars, I caress her stump. She tells me it’s quite sensitive, because all the nerves that used to ran all the way to her feet had to end there. Yes, Erin is beautiful, and not only because of her slender body, her flat belly and her exquisite ass. She is beautiful because of her missing leg, the rectangular patches of whitish skin in her thighs and her scars. Those things speak of her story, her suffering and her ability to overcome it. They show that her good mood and her easy smiles are her conquests, her triumph over bad luck. They show that she has more strength that most of us will ever have. I wrote this article in 2013, while I was dating Erin. She loved it and showed it to all her friends. She left me in June that year. Soon afterwards, in November, she took her life. It seems that what she told her mother was true: it was too painful for her to live without her leg.