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Breaking Down Addiction Into Its Constituent Parts: Neuroscience, Incentive Salience, Environment, and Habits

Dr. Daniel H. Lende

Daniel Lende is an associate professor from the department of anthropology at The University of South Florida. He was trained in medical, psychological, and biological anthropology and public health at Emory University in Georgia. His research interests revolve around substance use and abuse, behavioral health, stress, cancer, post-traumatic stress disorder, embodiment, interventions in behavioral health, and risk-factor epidemiology. He has done fieldwork research in both Colombia and the United States. Dr. Lende and Dr. Downey (the other author of our class book) started Neuroanthropology, which is one of The Public Library of Science (PLOS) Blogs.

Addiction and Neuroanthropology

“Addiction and Neuroanthropology” by Daniel H. Lende is a multifaceted explanation of the neural and cultural processes intertwined in drug seeking behavior and addiction. A difference between Colombian ideologies of addiction and North American ideologies is that in Columbia, the problem of addiction doesn’t revolve around pleasure. In Columbia, addiction defies their basic social value, which is protecting family, friends, and the community. In this context, addiction is problematic because drug seeking and using surpasses basic social values. In the United States, however, pleasure is one of the main concerns about addiction. It is viewed as a disease that develops due to one’s biology and self-control. Lende uses both a combination of previous neuroscientific evidence in conjunction with his ethnographic fieldwork to explain how addiction is not a problem of pleasure or the self, but a neuroanthropological conglomerate of a host of factors.

Lende states that addiction is composed of two parts, the compulsive desire for a drug and the drug habit that is formed. Addiction, according to the Diagnostic and Statistical Manual (DSM) consists of four parts. The first criteria are that addiction involves the experiencing of tolerance and withdrawal. The second discusses how addiction also involves continued drug use despite their impact on health and one’s social life. The third further explains addiction as the persistent desire to use drugs after multiple failed attempts at controlling use. Lastly, the fourth criteria are about how drug use interferes with daily life and roles and obligations are neglected.

So, what drives the actual behaviors associated with addiction? The 1993 theory of addiction proposed by Robinson and Berridge claims that incentive salience is the reason for addiction. This theory led to widespread belief that the mesolimbic dopaminergic pathway was singlehandedly responsible. Lende proposes that this view of addiction is problematic and desire and involvement, or the cultural aspects of drug use, are a couple of the components missing from this explanation.

Neuroscience and Addiction

Previous studies have shown us that addiction involves many interconnected brain areas such as emotion, memory, and choice. Addiction encompasses the basal brain, which is involved in body regulation and activation, limbic circuits associated with emotions and environmental processing, and frontal cortices, which are associated with executive functions such as control, planning, and organization. The neuroscientific aspect of the pursuit of drugs and the repeated use of drugs involves two parts of the mesolimbic pathway, the ventral and dorsal striatum and the ventral tegmental area.

Incentive Salience and Addiction

Reward theory states that environmental stimuli shape animal responses. Berridge and Robinson believe that there are three facets to the reward process. The first is liking, or the hedonic impact, learning, or making predictive associations, and lastly, wanting, or incentive salience. Incentive salience is a type of “wanting” that involves goals, expectations, and future outcomes. Salience, however, is still not the complete picture because desire and involvement are both biological and cultural. Incentive salience is mediated by both the nucleus accumbens and the ventral pallidum. Furthermore, individual experiences, the presence of cues, social contexts, and environmental influences all produce different patterns of firing resulting in differences in salience signaling.

An example that provides a better understanding of the behavioral side of the explanation is adolescent drug use. Students with problems in their home life and academic problems at school see few options for fun, success, or a sense of involvement in either of these settings. When rewards from school and family are absent, these two contexts become irrelevant and lose their incentive salience, therefore, students seek other options and other realms where rewards are provided and incentive salience is present. As Berridge et al. (2009) would sum it up, incentive salience is about a subjective sense of “this matters,” rather than conscious desire. Incentive salience is about the motivation of drug seeking rather than the appreciation of wanting or desiring drugs.

Neuroscience and The Formation of Habits

Habits, as defined by Graybiel (2008), are “learned, repetitive, sequential, context-triggered behaviors performed not in relation to a current or future goal but rather in relation to a pervious goal and the antecedent behavior that most successfully led to achieving that goal.” Habits are a product of both behaviors and neurobiology.

Neurologically, learning about the rewards associated with drug use activates the ventral striatum. As drug use becomes persistent and repetitive, a neural activation shift takes place from the ventral striatum to the dorsal striatum, where activation here serves to maintain drug seeking and drug using habits. Due to this shift, the ventral striatum, which serves to evaluate outcomes and consequence of behaviors, no longer serves its function and behaviors are mechanically produced. Despite increased tolerance, habits mediated by the dorsal striatum become resistant to change regardless of the rewards reaped by that behavior.

An example of this is extinction training in lab rats. Rats trained to press a lever that delivers drugs exhibit neurobiologically mediated behaviors associated with the dorsal striatum. When placed in a different context where lever pressing does not yield drugs, rats continuously lever press although no drugs are administered. Only when the dorsal striatum or nucleus accumbens are lesioned do rat lever pressing behaviors cease.

Behavior and The Formation of Habits

This neurological explanation leads people to believe that addicts find little pleasure in continued drug use. However, behaviorally, drug use may still be a rewarding activity. The social interactions associated with drug use are rewarding despite the blunting of the pharmalogical effects of the drug. Once addiction sets in, oftentimes familial relationships and community involvement decreases and strong social bonds develop between drug users. Even without the same extent of high, the social networks formed with drug users become a major source of social interaction. Additionally, stress increases dorsal striatum activation which further reinforces habitual behaviors.

Summary

Drug use has more incentive salience than other areas of one’s life and becomes habitual. Increased drug use is reinforced because of social bonds between drug users, the neurological rewards associated with the high of the drug, and the activation of habit solidifying brain regions. The more involvement in drug social groups, the more incentive salience signaling increases and drug users seek drugs out even more. This complicated picture of drug use shows how addiction is both neurological and anthropological.

Similar Research

This chapter reminds me of our very first readings that discussed nerves, synapses, neurotransmitters, and different regions of the brain. It also reminds me of the second week’s readings about the encultured brain. Addiction is a perfect example of how the brain is encultured. This chapter shows how a neurological structure could influence behaviors and how an individual’s environment and behaviors also serve to reinforce neural activation patters and solidify these behaviors. This reading also reminded me of articles written by Dr. Gilbert Quintero, a cultural anthropologist who researches the social, cultural, and political economic aspects of drug use. Like Lende, Quintero has also studied young adult populations in the United States.

Towards the end of the chapter Lende touches on the idea of cultural models and how they play a role in the addiction process. If you all don’t already know, Dr. Bill Dressler, here in our very own anthropology department, conducts a lot of research on cultural models. His research focuses on how cultural consonance or discordance with salient cultural models may produce health benefits or may prove to be detrimental to one’s health. Next week’s reading on depression and anxiety discusses this concept further. People who are not culturally consonant with salient cultural models of a “good life” develop higher levels of anxiety than those who are culturally consonant. This relates to Dr. Lende’s argument because as we learned, higher levels of stress increase activation in the dorsal striatum. And as we know, the dorsal striatum serves to maintain and further perpetuate habits. Therefore, stress and anxiety associated with alienation from the community and family, coupled with societies’ negative view of addiction and the addict’s discordant lifestyle with salient cultural models, serve to dig a drug addict deeper into his or her drug pattern.

What I Liked or Didn’t Like

I liked how this chapter began by showing the contrasting ideologies behind addiction in Columbia and the United States. I also liked how the discussion progressed to an explanation of previous beliefs about drug use, addiction, and drug addicts. I believe that Lende’s approach of providing the reader with broader preconceived notions about addiction and his “busting” of these myths is an effective way to draw the reader in and provide alternate explanations. He talks about how historically, people have either taken a strictly neurological approach to addiction or a strictly behavioral approach to addiction. Then, he mends these two arguments by explaining how both are intertwined and are required for an accurate and holistic explanation of addiction.

What I thought was lacking was the organization of the chapter. I felt like there were certain areas that could be more condensed and straight to the point. I also felt that information that should have been presented together was scattered around which made it a little more difficult to grasp. This disorganization made the reader fetch for information and have to piece it all together for a comprehensive understanding. Similarly, I felt that a summary at the end of each section with the key take away points would have been beneficial to understanding how each component of the argument ties into the argument as a whole.

 

Questions for Pondering

  1. If the nucleus accumbens and the dorsal striatum are responsible for forming habitual drug seeking behaviors in addicts, why don’t we just lesion those brain areas?
  2. Why do you think that current drug rehab programs so often fail to change addictive behaviors?
  3. Using what Lende has shared with us, how could we use this knowledge to develop a more effective treatment process?
  4. Some children with negative home lives do not turn to drugs while others do. What do you think determines whether a child turns to drugs or not?
  5. Nature or nurture? Which do you think takes precedent in the context of addiction? Why?

The Equilibrium System: Our Malleable Mental Module

Greg Downey conducts research on the physiological, perceptual, and phenomenological impact of physical exercise. He is particularly interested in the effects of skill acquisition on cognitive and sensory learning, in the context of sports and dance. Downey believes that human variation stems from patterns of enculturation of the body and the brain. He is the author of the chapter titled, “Balancing Between Cultures: Equilibrium in Capoeira,” found in the 2012 book, “The Encultured Brain: An Introduction to Neuroanthropology”. Downey coauthored this book and also wrote a book in 2005 titled, “Learning Capoeira: Lessons in Cunning from an Afro-Brazilian Art”. Downey currently works in the department of anthropology at Macquarie University in Australia and teaches a variety of topics including human rights, ethnographic research methods, economic anthropology, and global poverty. He conducts fieldwork in Brazil, the United States, and the Pacific and studies practices such as mixed martial arts, echolocation in the blind, cognitive skills in sports, and metabolic changes in free divers.

Downey’s chapter narrows in on the neurological enculturation of the human sensory systems; specifically, those associated with equilibrium. By contrasting Afro-Brazilian capoeira practices with gymnastics techniques, Downey depicts the pliability of the human equilibrium system. Through this comparison he demonstrates how cultural patterns are responsible for differences in physical balancing skills. Proprioception is a multisensory system that functions in our periphery without conscious monitoring, until something goes wrong and our sense of balance is disturbed. The vestibular system is located in the inner ear where the semicircular canals and the otoliths (tiny ear bones) reside. These bones detect linear motion while the semicircular canals detect angular motion. Downey explains how this complex multisensory system consists of a feedback loop that allows individuals to detect their body positioning, correct for error, and anticipate future adjustments in order to maintain balance. While this function was previously thought of as a fixed neurological system, research shows that it is highly flexible and able to be refined via conditioning and training.

Gymnastics, ballet, martial arts, figure skating, and space travel are a few instances in which this vestibular system may be trained to perform in distinct ways. Superb balance after spinning in circles and the ability to mitigate motion sickness are a couple of examples of the plasticity of this system and how with practice, humans are able to acquire these unique abilities. Downey explains how differences in training and practice between gymnasts and capoeira practitioners allow for the strengthening of specific, but divergent vestibular skills. For example, gymnasts maintain a forward-facing gaze during hand stands while capoeira practitioners are not permitted to even look at the floor. Furthermore, gymnast movements are tightly controlled while capoeira movements are dynamic and mobile. Downey’s purpose in this comparison highlights how different cultural practices subsequently elicit and strengthen different neurological proprioceptive and motor skill sets.

This chapter reminds me of almost everything we’ve read in this class and the ongoing discussion about the bidirectional feedback loop and dynamic interaction between biology and culture. I am starting to associate the term “neuroanthropology” with the phrase “nature – nurture”. If we break down the term into “neuro” and “anthropology,” we are easily able to associate “neuro” with “nature” or “biology” and “anthropology” with “nurture” or “culture”.

I thoroughly enjoyed this reading. I enjoyed the organization of Downey’s thoughts and how not only did he strategically unfold his argument, but in order to further ones understanding of this phenomenon, he used examples from two disciplines that utilize the same sensory system in different ways and explained how this utilization yields diverse outcomes. I do wish, however, that a more neuroscientific explanation was provided for this phenomenon. As I was reading, I wondered specifically what mechanisms do scientists think are responsible for this mental modulation?

This chapter reminds me of the chapter titled, “Memory and Medicine,” by M. Cameron Hay. Similar to how memory systems can be reinforced by specific memorization practices found in different cultures, the equilibrium system may also be scaffolded and strengthened in a particular way. I see it as such: specific memorization techniques (culture/nurture) lead to the strengthening of specific neural pathways associated with memorization (biology/nature), which in turn, lead to specific memorization behaviors during memory recollection (culture/nurture/the individual). Analogous to this explanation is the following: specific balancing techniques (culture/nurture) lead to the strengthening of specific neural pathways associated with balance (biology/nature), which in turn lead to specific balancing behaviors during balancing practices (culture/nurture/the individual).

This chapter also reminded me that not only can sensation be culturally patterned but so can perception. Individuals living in different cultures may be culturally patterned to select, organize, process, and interpret information in different ways. Studies conducted by Segall, Campbell, and Herskovits (1963), using the Muller-Lyer Illusion test, reveal that there are cultural effects on the visual perception of optical illusions. Furthermore, another study conducted in 2009 by Ishi, et. al., researchers showed Japanese and American students images of familiar objects as wholes and as fragmented parts to determine if there are differences in analytical versus holistic perception. Findings show that American students were better able to identify the objects in the fragmented conditions when compared to the Japanese students. Researchers believe that this may be a reflection of American “individualistic” culture versus Japanese “holistic” or “collective” culture. These findings also coincide with what Downey presented in this chapter. It is important to acknowledge that visual perception is not natural, but rather cultural. Similarly, proprioception is also culturally mediated.

Questions to Ponder:

  1. Can you think of anything that is completely void of culture or not modulated by culture?
  2. What are some other examples of biological systems that were previously thought to be devoid of cultural influence?
  3. Can you think of a neurological study we can conduct to determine neurological similarities and differences between different culture’s vestibular dispositions?
  4. While understanding how culture impacts nature and vice versa, what dangers could we face when we begin to place cultural emphasis on differences?
  5. Can viewing biological systems in light of cultural influence cause for an increase in the categorization of people into groups, thereby creating harmful cultural constructions like race?

 

Further Reading:

Hay, M. Cameron. “Memory and Medicine.” In The Encultured Brain, D. Lende and G.   Downey, eds. (2012): 141-168. Cambridge: MIT.

Ishii, Keiko, Takafumi Tsukasaki, and Shinobu Kitayama. “Culture and visual perception: Does perceptual inference depend on  culture?” Japanese Psychological Research 51,2 (2009): 103-109.

Segall, Marshall H., Donald T. Campbell, and Melville J. Herskovits. “Cultural differences in the perception of geometric illusions.” Science 139,3556 (1963): 769-771.

The Bidirectional Relationship Between the Brain and Behavior

Memory and Medicine

Cameron Hay is a cultural anthropologist who specializes in medical and psychological anthropology. Her research endeavors revolve around understanding, experiencing, and coping with illness and disease from the perspective of patients, family members, and health care providers. The goal of her research is to facilitate mutual understanding between patients, physicians, and public health experts in order to allow for enhanced communication, ultimately leading to better health outcomes. Specifically, she hones in on the social distribution of medical knowledge, health disparities, health literacy, empathetic communication, healer-patient communication, health care decision making, experiencing chronic illness, and psycho social stress and health. Hays is currently a professor and the chair of the department of Anthropology at Miami University in Oxford, Ohio. She also serves as the director of the Global Health Research Innovation Center and the coordinator of the Global Health Minor at Miami. Her secondary position is at the University of California in Los Angeles where she works as a researcher at the Center for Culture and Health at the Semel Institute for Neuroscience and Human Behavior.

Hays conducts ethnographic research in Lombok, Indonesia. Her case study titled, “Memory and Medicine”, that was featured in the book, “The Encultured Brain”, is a comparative study of the memory systems of Sasak healers and American physicians. This chapter is an analysis of contrasting medical practices of rural traditional Indonesian healers from the island of Lombok and urban biomedical doctors from California. Knowledge, memory, and memorization are the three key concepts that are employed in both healing systems. However, the extent to which each of these is deferentially used is crucial to understanding how medical information is socially and neurologically organized. Hays believes that different medical traditions utilize different types of memory systems which bolster the neurological memory processes in different ways. Three key arguments that shape her research are that memory and medicine co-evolve within local contexts, the co-evolution of these processes are not only evident in the analysis of medicine, and in order to understand her argument, we have to mend the gap between biological science, social sciences, and humanities.

Hays believes that the reason why neurological differences exist between these two types of healers is not because one practitioner is more intelligent than the other, but rather the neurological processes elicited in the memory encoding, organization and retrieval processes are intertwined with social, technological, and institutional traditions specific to that culture. In order to heal, the Sasak use jampi, or memorized formulas that are solely orally transmitted to selected individuals. Anxiety invoked during memorization is believed to enhance the memory encoding process. In America, formal training consisting of learning through evidence based scientifically published articles. In contrast to the Sasak, emotional anxiety is discouraged and viewed as a breech of clinical objectivity. Sasak medical tradition utilizes episodic memory which elicits the use of the hippocampal associative systems and is bolstered by emotional reactivity of the amygdala. American medical tradition utilizes a combination of episodic memory, semantic memory and procedural memory. The integration of medical knowledge is facilitated by the hippocampus but once schemas, or representative models are formed, schemas can be accessed independently of the hippocampus. Overall, Hay’s main argument is that any knowledge set is biocultural and influenced by differences in local assumptions, information distribution, learning and remembering processes, and the strengthening of certain neural pathways.

This article reminds me of several articles that I have read about fire walkers. Fire walkers are oftentimes able to recall specific details about their experience during this rite of passage.  This enhancement in memory is because the event was emotionally significant, causing their amygdala to become highly active, which assists with memory storage. Similarly, better memorization of a jambi formula may be due to the anxiety invoked when slapped on the arm. The ability to recall particular details about one’s fire walking practice or a specific jambi line is associated with the consolidation of episodic memories. This article also reminds me of the idea of synaptic pruning and the brains remarkable plasticity. For example, the brains of blind individuals show weakened neural associations within the visual cortex but enhanced neural associations in other brain regions such as those associated with sound.

I enjoyed reading this article but was also hoping she would have included articles in support of her suggestions. I wished there was an accompanying study depicting neurological evidence of a correlation between higher rates of neural activation in certain brain regions and specific health care providers. She mentions that the bridging of disciplines in order to enhance biocultural understanding is valuable, however, she fails to display this transdisciplinary and collaborative research essence in her own work. I also recognize that she may have other studies that do exactly what she proposes. What I did not fully see in her article is the applicability of her research. I understand why it is important that the brain is able to shift and differentially allocate resources to certain regions but other readers may wonder why it is important to know that some healers predominately use a specific type of memory. How is this research valuable and applicable to us? Most grant proposals and published articles require an explanation of the “bigger picture”. What I did not grasp as well was this “bigger picture” and exactly what her research contributes to the field of neuroanthropology.

Questions to Consider

  1. How can we benefit from this newly learned knowledge about the influence of cultural practice on neural pathways and the recollection of memories?
  2. What type of hypothetical research project could we propose to test the validity of the idea that health care traditions strengthen certain specific neural pathways?
  3. How can you use the “use it or lose it” phenomena to explain why certain neural pathways are augmented in healers cross-culturally?

Body, Brain, and Behavior: The Neuroanthropology of the Body Image

Charles D. Laughlin is currently a professor of religion at the University of Ottawa and is a professor emeritus of the Carleton University in Ontario, Canada where he previously taught anthropology and religion. Laughlin is interested in a theory that he and his friends, Eugene G. d’Aquili and John McManus, developed during the 1970s and 80s. The theory of biogenetic structuralism is a type of neuroanthropology that incorporates the brain, consciousness, and culture. Laughlin has devoted a large part of his career to collecting ethnographic data in Northeastern Uganda. Later, his interests in consciousness and the ways in which societies structure and interpret alternative states of consciousness led him to live in various Tibetan Buddhist monasteries in Nepal and India.

Lauglin’s article titled, “Body, Brain, and Behavior: The Neuroanthropology of the Body Image”, focuses on how an individual’s neurocognitive model of his or her body is comprised of a combination of internal and external sensory systems. He defines body image as, “a dynamic set of models within their cognized environment that integrates currently anticipated and remembered perceptions of their body, as well as all other habitually entrained neural networks producing affect, cognitions, and habitual motor patterns related to their body”. He proposes that the model of the body is already present within each individual upon birth but develops and takes shape through genetic predispositions and subsequent sociocultural influences. Prior to explaining his position, Lauglin provides the reader with a list of traits associated with the neuroanthropological theory of body image. He states that the body image is a construct of the nervous system, the body is transcendental relative to body image, and behavior controls perception so that the body perceived matches what is expected. This means that the ability to acknowledge one’s body is innate, developing prenatally, the actual physical body is much more complex than the nervous system’s model of it, and lastly, behavior provides a negative feedback loop so that individuals act in accordance with their desired body image.

Lauglin describes how the nervous system models the environment within the body by explaining the neural networks that are involved with body image development. He lists the different types of memory images and indicates that eidetic imagery, or images that occur vividly but are not perceived as real, may be used to change one’s body image. Lauglin also explains how the multiple representation model, or the belief that verbal and imaginal systems are distinct and independent modes of representation, is the most widely believed model, as opposed to collapsing both systems. He breaks down this model by explaining how the right hemisphere predominantly processes nonverbal imagery while the left hemisphere processes verbal symbolism. Lastly, Lauglin discusses how body image may be changed by using clinical methods that utilize ritualized visualizations and guided imagery may prove to be therapeutic and help change negative body image.

I enjoyed reading this article because body image is such a fascinating topic and a very salient topic as well, especially on a college campus. This article reminds me of the use of cognitive behavioral therapy (CBT) and dialectical behavioral therapy (DBT) to help alter maladaptive thought patterns. Lauglin’s article also relates to other articles I have read that discuss how facial and physical symmetry are one of the few characteristics that are seen as attractive and desired features of a prospective mate cross-culturally. I believe that from an evolutionary anthropology perspective, physical and facial symmetry are subconscious indicators of health and fertility. Symmetry may be an indicator of superb genes and people may subconsciously seek more symmetrical mates in order to reproduce with an individual who is more fertile and more likely to yield healthier offspring.

With respect to physical body size, the notion of attractiveness also varies from culture to culture. Some regions in the Middle East and Africa believe that larger body size indicates wealth since they can afford to eat and become large. Furthermore, larger body size may also be indicative of health and reproductive capacity since being undernourished may cause for fetal termination since it may not have enough nutrition to survive to birth. On the other hand, in America, it is believed that those who are thinner are wealthier since they have the means and resources to purchase higher quality foods or can afford to spend their money on gym memberships and their time exercising instead of working. Neither of these “indicators” may actually be true but this article led me to wonder about how body image disorders develop and why.

Questions to Consider

  1. What are some current ways in which body image disorders are currently being treated and how can we improve upon these methods according to Lauglin?
  2. Do you think that certain cultures have an increased incidence or prevalence of body image disorders compared to others? Ie. Do women in America have more rates of anorexia because thinness is portrayed in the media? Or do women in South Africa have more rates of binge eating disorder because being overweight is valued in that culture?
  3. Tying in Hay’s article, do you think that the neural pathways associated with negative body image are strengthened over time while positive body image pathways are weakened? Do you think this impacts one’s memory encoding, organization, and retrieval processes in any way?

Monika Wanis – Why I like extreme sports!

2010 Skydive with “Tree Man” in Middletown, Ohio

Hi! My name is Monika Wanis, I am a second year Biocultural Medical anthropology graduate student. I am originally from Cairo, Egypt but have lived in Columbus, Ohio for the past 20 years. I attended The Ohio State University for my undergraduate degree in Anthropology, Psychology, Integrative Medicine and Neuroscience. I speak Arabic, English, Spanish, and Russian. I am also currently a TA for 2 sections of Cultural Anthropology. My favorite hobby is doing any extreme sport. I went skydiving on August 27th of this year for the second time for my birthday! According to Tinbergen’s 4 Questions Why, here is why I like extreme sports:

Proximate Causes

  • Mechanism – Physiologically, extreme sports often involve behaviors that increase your heart rate and produce a surge in hormones such as cortisol and adrenaline and neurotransmitters such as norepinephrine and dopamine. These substances may cause feelings of happiness and euphoria, therefore providing positive feedback for the extreme behavior and potentially creating a feedback loop.
  • Ontogeny – My interest in extreme sports has developed over a lifetime. I don’t think I was born with an innate desire to jump out of airplanes. I may have been born with a slight bias towards risky behaviors but then through interactions with people who are involved with extreme sports, I became attracted to the hobby and over time, began experiencing and enjoying them more.

Ultimate Causes

  • Adaptive Value – While extreme sports may appear to be in contrast to increasing my reproductive fitness, it actually may contribute to it! If I were to die doing an extreme sport then obviously it does not contribute to my reproductive fitness. However, doing extreme sports and surviving may be a mechanism of sexual signaling to onlookers that indicates that although I engage in these risky behaviors, I am strong/smart/clever/etc. enough to survive, thus, increasing my my mating and reproductive potential because those are characteristics that increase my chances of survival.
  • Phylogeny – This interest in extreme sports may have evolved to set myself apart from the rest. Due to an increase in education levels, income, competition in the job market, an interest in extreme sports could be an evolution due to these selective pressures. Practicing extreme sports is a behavior that is different from what is traditionally seen as a desirable characteristic in a mate, therefore, it may have evolved as an additional characteristic that may be seen as desirable.