Daniel Kelly, Yuck! The Nature and Moral Significance of Disgust (2011)

I have an aversion to lima beans.  aver·sion,  noun \ə-ˈvər-zhən, -shən\                                              

: a strong feeling of not liking something.  **** 2

a :  a feeling of repugnance toward something with a desire to avoid or turn from it aversion >

b :  a settled dislike :  antipathy aversion to parties>

c :  a tendency to extinguish a behavior or to avoid a thing or situation and especially a usually pleasurable one because it is or has been associated with a noxious stimulus

Yuck!  But is this aversion a form of disgust?  dis·gust noun \di-ˈskəst, dis-ˈgəst also diz-\

: a strong feeling of dislike for something that has a very unpleasant appearance, taste, smell, etc.

: annoyance and anger that you feel toward something because it is not good, fair, appropriate, etc.

:  marked aversion aroused by something highly distasteful :  repugnance

 

I find lima beans distasteful, noxious.  I avoid eating them.  Apparently, I am not the only one. Years ago as a child, I felt the same way toward other food items, but today only lima beans remains associated with a noxious stimulus of some kind that I cannot define.  I know well that others like lima beans and are not harmed by them, but something triggers certain neurons firing in my brain that creates this reaction to the lima bean.  Are lima beans disgusting, by which I intend to describe lima beans an elicitor of disgust?  By definition, lima beans are disgusting . . . at least to me.  dis·gust·ing, adjective

: so unpleasant to see, smell, taste, consider, etc., that you feel slightly sick

: so bad, unfair, inappropriate, etc., that you feel annoyed and angry

 

You see in these definitions of disgust and disgusting two distinctive feelings.  One centers on an aversion, dislike or repugnance toward something  that is distasteful, or suffers from a bad smell or appearance; although the definitions do not elaborate on what is distasteful or smells bad, it is easy to think of something associated with the mouth and ingestion such as rotten food or a poison.  The second feeling centers on a dislike for another group or behavior considered annoying or unfair by some standard.  In both cases, the consequence of the feeling is likely rejection:  rejection of the noxious substance; rejection of the other person or group.

 

Paul Rozin at the University of Pennsylvania and Jonathan Haidt at the University of Virginia and now NYU have devoted more attention and research to the subject of disgust than anyone else at this moment in time.  In their contribution to the 1999 edition of the Handbook of Cognition and Emotion entitled Disgust:  The Body and Soul Emotion, they made several key points and arguments:

• Distaste and disgust are different.  Other animals, particularly other mammals, show they react to ingesting a substance because it is distasteful by rejecting it.  Disgust, on the other hand, is uniquely human because, in addition to some biological rejection of distasteful or foul smelling substance, the feeling has a cognitive content that is not elicited by sensory properties.  Like other emotions, disgust links together cognitive and bodily responses, which can be analyzed as an affect program, in which outputs (behaviors, expressions, physiological responses) are triggered by inputs (cognitive appraisals or environmental events).  While the biological outputs that represent disgust have been reasonably stable among human populations over time, there has been an enormous expansion on the cognitive appraisal side, which expansion varies with history and culture and takes disgust far beyond its animal precursors and well beyond an aversion to lima beans.
• For humans, the elicitors of core disgust are generally of animal origin, although there is research that plants and vegetables can elicit core disgust. 
• The rejection response is now harnessed to the offensive idea that humans are animals, and thus disgust is part of affirming our unique humanity by suppressing every characteristic that we feel to be 'animal'.  They call this animal nature disgust and distinguish it from core disgust.  The cognitive notion here includes associating something deemed disgusting with something labeled impure. 
• There is also another form of disgust they call interpersonal disgust, which is rejection of persons outside one's social or cultural group.  Hindu caste behavior is a prime example, but there are hundreds of other examples, racial, religious, and the like, that are readily recognized.
• Finally, thee is social-moral disgust where violations of social norms trigger a feeling of disgust.  Not all violations of social norms trigger disgust.  Bank robbery they point out, while viewed as "wrong," does not trigger necessarily disgust or rejection. 

There has been much written in recent years about disgust as a moral emotion or the potential nexus between disgust and moral judgments/ethical norms.  The example of incest avoidance is one example of "moral" behavior that is at the heart of this discussion.  Avoiding consumption of lima beans is not, and I am reasonably certain that the avoidance of lima beans is not considered a "moral behavior" across any culture or society.  Marc Hauser described disgust as "the most powerful emotion against sin, especially in the domains of food and sex. . . . In the absence of a disgust response, we might well convince ourselves that it is okay to have sex with a younger sibling or eat vomit, act with deleterious consequences for our reproductive success and survival respectively."  Incest avoidance is worthy of study -- in contrast to my aversion for lima beans -- because it is virtually universal across cultures, and is therefore almost unique among things humans generally avoid.   Aversion to eating pork, for example, is not universal, and like lima beans there is a substantial part of the human population that likes eating pork and is not harmed by eating pork.  In some cultures, the avoidance of eating pork is considered a "moral behavior." 

Disgust did not begin as a moral or even a social emotion.  There is common agreement, among those who have studied disgust that the emotion's evolutionary origins lie in response to the ingestion of something: spoiled food, toxins; it later evolved as a response to the presence of disease and parasites, which is referred to as core disgust.  Daniel Kelly documents this body of research in Yuck!  And a common feature of this emotion is the automatic facial feature called face gape.  As one article explains, "At its root, disgust is a revulsion response -- "a basic biological motivational system" -- that Darwin associated with the sense of taste. Its function is to reject or discharge offensive-tasting food from the mouth (and/or the stomach), and its fundamental indicator, the "gape" or tongue extension, has been observed in a number of animals, including birds and mammals. In humans, the characteristic facial expressions of disgust that coincide with gaping include nose wrinkling and raising the upper lip, behaviors usually accompanied by a feeling of nausea and a general sense of revulsion. Together these behaviors and sensations facilitate the rejection of food that has been put into the mouth."  Evolutionarily, disgust began with distaste, but at some point it adapted in humans to protect against infection by pathogens and parasites.  Daniel Kelly explains his thesis that the two responses became "entangled."  "Other previously puzzling features of disgust also fall into place once its role in parasite avoidance becomes clear.  Together, eating and sex constitute two of the most basic evolutionary imperatives.  Both behaviors are unavoidable ingredients of evolutionary success, but both involve the crossing of bodily perimeters at various points.  By virtue of this, both activities leave those engaging in them highly vulnerable to infection.  The upshot is that disgust's role in monitoring the boundaries of the entire body (rather than just the mouth) makes much more sense in light of its connection to infectious disease.  Moreover, both feeding and procreating are activities that require those boundaries to be breached.  They are highly salient to disgust both because they are universal and unavoidable and because they are two of the most potent vectors of disease transmission."  It is this entanglement of distaste and core disgust that is unique to humans.  There is evidence that each is independently found in other species.

Importantly, disgust appears to be activated in the cortex. Kelly identifies the insula, which is not part of that ancient subcortical system of the forebrain or midbrain that Jaak Panksepp documents is associated with basic emotional systems.  (See May 19, 2013 post).  The word disgust never appears in Panksepp's book and is not even found in his description of the fear system involving in the amygdala and the hypothalamus which, because fear stimulates flight, sounds like it might be related to an emotion like disgust that stimulates avoidance.  On the other hand, Kelly identifies an area of the forebrain, the putamen, as an area of the brain associated with processing disgust, but the putamen is involved in emotional facial recognition, so it may not be something disgusting that activates the putamen, but the recognition of face gape that activates the putamen.  The putamen is primarily associated with the motor cortex, so the connection to the putamen as an emotional processor is not at all that clear.  I suspect that the putamen, if it is implicated in disgust, it is not part of what Rozin and Haidt refer to as inputs (cognitive appraisals or environmental events), but our biological output that results in virtually automatic, nearly uniform facial expressions.  Research on patients with Huntington's Disease would seem to confirm this observation.  But the insular cortex is involved in maintaining the homeostatic condition of the body; it maintains an awareness of various parameters of the body;  the insula is also believed to process convergent information to produce an emotionally relevant context for sensory experience. More specifically, the anterior insula is related more to olfactory, gustatory, vicero-autonomic, and limbic function, while the posterior insula is related more to auditory-somesthetic-skeletomotor function. The insula has an important role in pain experience and the experience of a number of basic emotions, including anger, fear, disgust, happiness and sadness. If disgust is seated in the insular cortex, this would confirm the significance of cognitive appraisal in producing disgust. The insular cortex is a mammalian development, so it evolved later than those ancient emotional systems that Panksepp discusses.

Morality varies across cultures and even within cultures and smaller social groups.  Edward Westermark advanced the thesis that there was an innate aversion to sexual intercourse between persons living very closely together from early youth, and as applied to persons who are closely related this generates a feeling of horror of intercourse with close kin.  But is this aversion really innate?  Or is it learned?  Or is something innate triggered because, in this case, one must first experience living closely with someone at an early age?  Because there is survival value associated with avoiding inbreeding, there is arguably an evolutionary imperative associated with incest avoidance and should explain in substantial part why incest avoidance is universal across cultures. Inbreeding reduces the fitness of a given population. Incest avoidance seems to have nothing to do with morals.  If it is considered moral behavior, it is only because humans have put that label on a form of behavior that likely predates social norms and morals.  If it is considered disgusting, it is only because humans have put that label on it. 

Outside the example of the inversion to inbreeding, interpersonal and social-moral disgust is something that is learned.  It is not innate.  Rozin observes that up to about two years of age, children show no aversion to primary disgust elicitors such as feces.  Toilet training may be the learning event that leads to core disgust.  Later in childhood development, an event or object that was "previously morally neutral becomes morally loaded."  At this point in the learning process, disgust becomes recruited.  Disgust "becomes a major, if not the major force for negative socialization in children; a very effective way to internalize culturally prescribed rejections (perhaps starting with feces) is to make them disgusting." 

Kelly theorizes that disgust migrated from being an emotional response to toxins, parasites and disease to a socially shared emotion because face gape is automatic and the emotion as revealed in the facial gesture was communicated in a way that was empathetically received.  Like other facial communications (see July 16, 2010 post), there is a reliable causal link between the production of an emotion and its expression here that acts as a signal to avoid.  And to the extent that group selection (or more narrowly kin selection) is engaged, shared disgust becomes a survival mechanism for the group to avoid toxins, parasites and disease,  Kelly posits that the genetic underpinnings of the neural correlates of the emotion and gape face were recruited by human culture to perform several novel functions.  And what the emotion qua emotion of disgust has in common with the socially shared emotion is that the object of the emotion's attention is distasteful and/or impure.  As a cultural phenomenon, the socially shared emotion becomes connected to social, moral or ethical norms, group identity and avoidance of others.  Culture then labels something to be avoided or averted as disgusting. 

Social or ethical norms are not necessarily social or ethical norms because of a common emotional stimulus like disgust, although they could be and common aversion to foods and attitudes toward sexual behaviors within a culture are a few examples that coms to mind.  Because most social norms are learned and not instinctual, interpersonal and social-moral disgust is little more than a social label for one's attitude toward behavioral transgressions of group rules.  Interestingly, the label may not be shared by all within the group.  Consider, for examples, how societal attitudes toward homosexuality --- a behavior that large segments of many societies consider "disgusting" --- are rapidly changing.

Kelly concludes, disgust is "far from being a reliable source of special, supra-rational information about morality" and we should be extremely skeptical of claims that disgust deserves any "epistemic credit" as a trustworthy guide to justifiable moral judgments or deep ethical wisdom in repugnance.  Justifying a moral or ethical rule on disgust can easily slide in dehumanization and demonization itself, which in itself is problematic.  There is a ready and recent example that highlights Kelly's concern in today's news that the youthful leader of North Korea had his elder uncle, also in the leadership of North Korea's government, executed for treason.  In language that recalls Rozin and Haidt's discussion of animal-nature disgust, the uncle was labeled  as "despicable human scum" and "worse than a dog," and said he had betrayed his party and leader."  In other words --- particularly with the association to animals and scum (certainly there are parasites and disease in scum) --- the uncle was disgusting.  His purported "disgustingness" became a post hoc justification for his execution.

This entire discussion implicates the relationship between genes and culture, and Kelly devotes an entire chapter to "gene culture coevolution," sometimes referred to as the dual inheritance theory.  (See September 12, 2012 and June 17, 2010 posts) and its application to the evolution of disgust. Rozin and Haidt concur:  "The interaction between biology and culture is clear, because the output side of disgust remains largely ruled by biological forces that originally shaped it, while the input/appraisal/meaning part has been greatly elaborated, and perhaps transformed in some cases."

Christopher Boehm, Moral Origins, The Evolution of Virtue, Altruism, and Shame (2012)

Anthropologist Christopher Boehm is interested in this question:  Why did humans evolve a conscience?  Before exploring this question and what Boehm believes may be the answer to his question, I want to develop some facts and opinions of others on issues that I believe bear on this question, some of which Boehm does discuss and some of which he does not discuss in his book Moral Origins.

The first issue I want to address is the role of emotions, and in particular the social emotions in the origins of human morality.  Boehm concludes Moral Origins by saying that in a few generations we "may have identified some of the genetic mechanisms that help us to behave egoistically, nepotistically, and altruistically, along with others that make for sympathetic generosity, domination and submission, and a variety of other socially significant behaviors that are relevant to morality, including our shame responses."  Boehm may well be right that we will identify the genetic mechanisms behind moral and immoral behavior in a few generations, but the roadmap of investigation is already before us and it begins with emotions.  I say this for two reasons:  first, if anything, genes code for our body chemistry; genes may or may not code for specific behavior (moral or otherwise), although I doubt it (see November 30, 2009 post).  But emotions are driven by electro-chemical actions and reactions in our various body systems and ultimately the neurological system leading to our brains, and genes do code for these electro-chemical actions and reactions and genes code for our brain and other body organs.  If we want to understand the genetic basis for moral and immoral behavior we will look for the genes tied to these body systems and the chemistry that drives emotions.  The second reason is not biological, but an observation that philosophers have made since the 18th century: that emotions, and in particular certain social emotions shape our "moral sentiments." (See April 8, 2011 post).  I am thinking particularly of David Hume (see February 27, 2011 post)  and Adam Smith (see January 11, 2011 post).  Research is beginning to show that emotions trigger moral behavior. 

The second issue is the growth of the brain in the evolution of hominids leading to homo sapiens.  Antonio Damasio's works confirm that the evolution of consciousness in humans is tied to the growth and development of the brain, particularly the cortical regions, and without "extended" consciousness apparently enabled by the larger human brain we very likely have no conscience.  (See April 8, 2011 post and October 25, 2011 post).  Damasio hits a theme in these two paragraphs from his book, Looking for Spinoza, that I quote at length below, and which I don't believe Boehm would disagree with:

"The construction of what we call ethics in humans may have begun as part of an overall program of bioregulation.  The embryo of ethical behaviors would have been another step in a progression that includes all the nonconscious, automated mechanisms that provide metabolic regulation; drives and motivations; emotions of diverse kinds; and feelings.   Most importantly, the situations that evoke these emotions and feelings call for solutions that include cooperation.  It is not difficult to imagine the emergence of justice and honor out of the practices of cooperation.  Yet another layer of social emotions, expressed in the form of dominant or submissive behaviors within the group, would have played an important role in the active give and take that define cooperation.

"It is reasonable to believe that humans equipped with this repertoire of emotions and whose personality traits include cooperative strategies would be more likely to survive longer and leave more descendants.  That would have been the way to establish a genomic basis for brains capable of producing cooperative behavior.  This is not to suggest that there is a gene for cooperative behavior, let alone ethical behavior in general.  All that would be necessary would be a consistent presence of the many genes likely to endow brains with certain regions of circuitry and with the attendant wiring --- for example, regions such as the ventromedial frontal lobe that can interrelate certain categories of perceived events with certain emotional feeling responses.  In other words, some genes working in concert would promote the construction of certain brain components, and the regular operation of those components, which, in turn, given the appropriate environmental exposures, would make certain kinds of cognitive strategy and behavior more probable under certain circumstances.  In essence, evolution would have endowed brains with the apparatus necessary to recognize certain cognitive configurations and trigger certain emotions related to the management of the problems or opportunities posed by those configurations.  The fine tuning of that remarkable apparatus would depend on the history and habitat of the developing organism." (emphasis added).

The social emotions: Shame, Sympathy and Empathy. The so-called "social emotions" --- embarrassment, guilt, shame, and pride --- are linked to moral behavior in humans, and therefore no discussion of moral origins can ignore social emotions. "It is highly probable that the availability of such social emotions has played a role in the development of complex cultural mechanisms of social regulation," writes Antonio Damasio in Looking for Spinoza. "It is also apparent that some social emotional reactions are elicited in human social situations without the stimulus for the reaction being apparent to the reactor and to observers." Damasio believes that the social emotions are buried deep in the organism's brain, innate rather than taught. (See April 8, 2011 post). Researchers have concluded that social emotions are not unique to humans. As Damasio observed in Looking for Spinoza, "Because the term 'social' inevitably conjures up the notion of human society and of culture, it is important to note that social emotions are by no means confined to humans. Look around and you will find examples of social emotions in chimpanzees, baboons, and plain monkeys; in dolphins and lions; in wolves; and, of course, in your dog and cat. The examples abound --- the proud ambulations of a dominant monkey; the literally regal deportment of a dominant great ape or wolf that commands the respect of the group; the humiliated behavior of the animal that does not dominate an must yield space and precedence at mealtimes; the sympathy an elephant shows toward another that is injured and ailing; or the embarrassment the dog shows after doing what he should not." (See also June 17, 2010 post).

Psychologists distinguish between basic emotions and social emotions.  Moral emotions are treated as a subset of social emotions.  Which emotions constitute the "basic" emotions is a matter of debate, but they at least include happiness, sadness, disgust, anger, and fear --- emotions that require an awareness of one's own somatic state.  These are ancient emotions that are tied to survival, driving us away from harm and directing us toward some reward.  Social emotions require the existence of a group, a theory of mind (TOM) and an awareness of the mental states of others.  The social emotions include embarrassment, guilt, shame, contempt, indignation, sympathy, compassion, gratitude and pride.  Following Jonathan Haidt's paper on The Moral Emotions, Antonio Damasio in Looking for Spinoza has described the basic emotions underlying the social emotions and what he calls the emotionally competent stimulus (ECS) for and consequences of the social emotions as follows:

Social emotion	ECS	Consequences	Basic emotion
Embarrassment, shame, guilt	Weakness or failure or violation in individual’s own behavior	Prevent or avoid punishment by others; restore balance to self or group	Fear, sadness
Contempt, indignation	Other individual’s violation of norms	Punishment or violation, enforcing of social norms	Disgust, anger
Sympathy, compassion	Another individual suffering, in need	Comfort, restoration of balance in other or group	Attachment, sadness
Awe, gratitude, pride	Recognition in others or self of contribution to cooperation	Reward for cooperation, reinforcing tendency to cooperate	Happiness

These social emotions, the ECS, and consequences become central to Boehm's discussion of moral origins.  Damasio's point:  "In a society deprived of such emotions and feelings, there would have been no spontaneous exhibition of the innate social response that foreshadow a simple ethical system---no budding altruism, no kindness when kindness is due, no censure when censure is appropriate, no automatic sense of one's own failings.  In he absence of the feelings or such emotions, humans would not have engaged in a negotiation aimed at finding solutions for problems faced by the group, e.g., identification and sharing of food resources, defense against threats or disputes among its members."  Boehm at least implicitly recognizes this in the subtitle of his book --- The Evolution of Virtue, Altruism and Shame --- but the genetic foundations of our emotions is not clearly called out.

Shame is particularly called out by Boehm as an emotion central to moral origins in humans, but I will address that more specifically later.  Boehm repeatedly treats sympathy and empathy as synonyms; they are not and I want to comment on that here.  But in discussing moral origins, Boehm is correct to emphasize "sympathy."  Sympathy, as Damasio's categories above suggest, is proactive: the consequence is for one person to provide comfort to another person.  As Frans DeWaal says in The Age of Empathy (see November 9, 2010 post), "Sympathy, in contrast, reflects concern about the other and a desire to improve the other's situation."  In contrast, "Empathy is the process by which we gather information about someone else."  Empathy is more of a feeling rather than an emotion.  As Jonathan Haidt writes in his article The Moral Emotions,  "Empathy is not an emotion at all; it is a tendency to feel whatever another person is feeling, including happiness, anger, or boredom."  With respect to empathy, we can recall the discussion of mirror neurons in monkeys, apes, and humans, that would facilitate these feelings.  (See October 25, 2011 post and July 16, 2010 post)  "Empathy is easily aroused," says DeWaal, but "sympathy is anything but automatic."  Sympathy is common in both humans, chimpanzees and bonobos who can be consoling.  Sympathy, however, would not occur without a capacity for empathy. 

This brings us to shame, embarrassment and guilt. Shame attracted the attention of Charles Darwin. He noted that humans universally blushed with shame that appeared to be associated with a moral conscience. This behavior is seen only in humans. By definition, shame is provoked when an individual recognizes that his or her own conduct (or perhaps the conduct of another group member, for example shame due to the conduct of one's own child or spouse) has transgressed the social rules or expectations of others.  Shame implicitly, if not explicitly, acknowledges the applicability of those social rules to one's own conduct.  It is similar to guilt, but guilt could apply to an individual's own rules and not merely social rules.  Boehm says that during his research in the African forest "the apes never appeared to me as though they were upset over their own behavior, let alone ashamed of it or remorseful. I did notice that between individuals there were postures and gestures that seemed to ask for or grant forgiveness, and in fact chimpanzees often make up after conflicts. . . However, this seems to be aimed merely at reducing tension or restoring positive relations, so reading a morally-based element of remorse into such behavior would be patently anthropocentric. Nothing I observed ever convinced me that there was something like morally based self-recrimination in the wild, for aggressors never appeared to be troubled by their actions afterward." How did humans come to blush with shame so predictably, asks Boehm? Much of the answer has to lie in biology, he says, but in considering actual selection process that might have supported the existence of a conscience Boehm's social selection' theory described above "explains the rather unusual set of agencies that created this moral faculty for us." Once shame feelings emerged "there would have been no question about [humans] moral status, reflecting that humans had strongly internalized group values and a sense of right and wrong," concluded Boehm. The expression of shame, guilt, and embarrassment enables the deviant to avoid punishment by others and restores one's place in the group.  But was the environmental trigger that induced the expression of the shame emotion in humans the behavior of other humans?  Although he does not expressly say this, Boehm's "social selection" theory seems to suggest this.

What we are ultimately interested in here is the development of altruistic behavior: direct and indirect reciprocal behavior (see September 27, 2012 post and September 12, 2012 post) in terms of the consequences described in Damasio's categories above, cooperation. What were the environmental drivers that triggered the development of moral emotions and ultimately the capacity to engage in altruistic reciprocal exchange, particularly that exchange that does not require direct reciprocal exchange?  As Martin Nowak observed in Supercooperators, "We are the only species that "can summon the full power of indirect reciprocity, thanks to our rich and flexible language."  (See September 17, 2012 post).

Human brain size and structure.  While the social insects demonstrate that cooperation is not a function of brain size (see November 4, 2009 post) , in hominids, I submit, it is highly relevant. Also relevant, according to recent research, are variations between species in the relative size of certain areas of this larger brain and the extent of interconnections between areas that can explain differences in temperament and behavior that translates into greater empathy and less aggression, which may or may not have co-evolved with the enlargement of the brain.  Also relevant may be differences in neurons between species.  (See November 9, 2010 post).  Boehm also believes this subject is relevant to his inquiry about the evolution of conscience, but he is not certain just how much weight to assign to his answer. According to Lynch and Granger in their book Big Brain, the chimpanzee has a brain size roughly 350-400 cubic centimeters (cc); the extinct Australopithecus, a brain size of about 440-450cc; extinct homo habilis, a brain size of about 600cc; the extinct homo erectus, a brain size of about 800cc-1000cc; the extinct homo heidelbergensis, a brain size of about 1200cc; the extinct neanderthal (homo neanderthalensis), a brain size of about 1500cc; and homo sapiens, a brain size of about 1350cc. In the evolutionary trail from the genus pan to the genus homo and the species within the genus homo, the brain enlarged over time (although the human brain has apparently shrunk in more modern times). The pan/homo divergence is believed to have occurred about 6 million years ago, and an emergent characteristic of the new species was bipedalism --- upright walking - which evolved with austalopithecines, perhaps as early as 3.6 million years ago, long before larger brain size. According to Lynch and Granger, changes to body that support walking increased lower trunk, and a side effect of a longer, lower trunk is to increase the space into which a uterus can expand during pregnancy. In women, this is accompanied by a wider pelvic girdle and the result is bigger babies. Bigger brains follows bigger babies. As the brain becomes bigger, most of the increase is not dedicated to sensory and motor needs, but to new neocortical areas. The biggest brains have much more cortex than smaller brains, and moreover, a bigger cortex has within it much more association cortex than sensory regions. This results in different relative intelligence for different brain size. Natural selection, conclude Lynch and Granger, did not select for intelligence. Intelligence was enabled by larger brains. Intelligence has been enabled by an expanded neocortex, which in humans is involved in higher functions such as sensory perception, generation of motor commands, spatial reasoning, conscious thought and language. The neanderthal evolved roughly 200-250,000 years ago in Europe and Asia; the homo sapien approximately 150-200,000 years ago in Africa. These capabilities of larger brains in homo sapiens did not emerge immediately. Language, for example, is not believed to have emerged until roughly 100,000 years ago. Language, I believe, is crucial for the evolution of a conscience, and Boehm appears to agree ("Morality is a group affair . . . Critical to this process is talking . . .").  Proto-languages, however, may have existed with earlier species such as homo erectus, but we will never know.  Equally critical to cooperative behavior in my view, particularly because it must be tied to indirect reciprocity, is the development of long-term memory, which is said to be encoded in the medial temporal lobe. 

As Antonio Damasio described above, parts of the prefrontal cortex are significant to social emotional associations, decision-making and moderating social behavior. Studies show that damage to a part of the ventromedial prefrontal cortex can impair empathetic responses in humans.  While other pan species have a prefrontal cortex, the prefrontal cortex of the human brain is significantly larger than that of chimpanzees, bonobos, and other apes, it also has more substantial folding (hence greater surface area) in this area than chimps and apes, and this has significant implications for behavioral differences that distinguish chimpanzees from humans.  Since we have seen that sympathy and empathy have been observed in the pan species, chimpanzees and bonobos, and that these species have prefrontal cortex structures similar, but not identical to humans, the human capacity for empathy and sympathy has its origins long ago in our non-human ancestors.  The larger brain capacity in homo, it is my belief, together with relative enlargement of certain areas of the brain and the connections between them, has probably contributed to their greater ability to engage in self-control over their egotistical impulses and greater empathy and compassion for other humans and perhaps other animals.  What we don't possess at this time is much in the way of research on the neural correlates of shame and guilt.  An Internet search came across only a couple of recent papers that acknowledged there had not been much research in this area, and that research might advance this discussion a bit.

Selfish or self-control?  In a prior post discussing Richard Wrangham's Demonic Males (see July 1, 2010 post), I noted, "If this was the only book one read on the subject of the origins of human behavior, you would conclude that male humans are born to kill, but empirical observation tells us that is not the only truism one can declare about male humans. Demonic Males is very interesting for what it documents: the apparent origins of human violence can be found in other primate species closest to humans, which indicates a genetic and evolutionary foundation for violent behavior among human males. But there is more to the story that primatologists are telling us about the commonalities among primate behaviors, including the origins of social cohesion, cooperation, and even morality and altruism. Michael Gazzaniga's Human (September 27, 2009 post) contributes much to this broader understanding of human evolution. Wrangham barely mentions these other common attributes of primate social systems. Violence is only one behavioral aspect of our social nature."  Boehm would agree that humans are very different than chimpanzees, and what he endeavors to explain in Moral Origins is that notwithstanding the fact that selfish, egoistic impulses are stronger in humans than altruistic impulses, humans have evolved a capacity for self-control that suppresses selfishness and campaigns for generosity and the Golden Rule. Boehm falls in the line of thinkers that includes Frans DeWaal and repeatedly emphasizes our dual nature:  we are selfish egoists and we are selfless altruists.  As I described in the post discussing DeWaal's The Age Empathy (see November 9, 2010 post),   "DeWaal takes aim at three myths: (1) the myth that our ancestors --- 4 foot bipedal apes --- ruled the savanna in Africa; (2) that human society is a voluntary creation of autonomous men; and (3) that our species has been waging war for as long as it has been around. Our ancestors were likely both prey and predator and survival favored genes that encouraged collaboration and companionship. The idea that humans were autonomous falsely presumes they had no need for anybody else and could voluntarily choose to live apart, uncommitted to anyone else or any place. A warlike initial state of nature that philosophers like Rousseau imagined that was overcome by social compacts is actually the reverse of human evolution: war on a grand scale, like we have known for centuries, came only after social hierarchies were formed and wealth was created. The early human species was probably defined more by social commitments and small scale collaboration that promoted primitive economic exchange and division of labor."  Moral Origins is an attempt to provide a historical account of how these social commitments and small scale collaboration evolved. 

Fire and group behavior.  Recall E.O. Wilson's view that a key event (but certainly not the only event) in the development of human eusociality was the mastery of fire.  (See September 12, 2012 post).  The nest, or its equivalent, is viewed by Wilson as a key to eusociality, and the campfire, according to Wilson, is the human equivalent of a nest found in other eusocial species.  For genus homo, mastery of fire occurred first during the era of homo erectus, perhaps as early as one million years ago but certainly 600-800,000 years ago, and long before the emergence of homo sapiens and homo neanderthalensis 200,000 years ago.  The development and use of early tools is also associated with homo erectus, and homo erectus may have lived in small bands of 30-50 men and women.  What we do not know is whether homo erectus' ability to control fire was merely the use of fire otherwise started naturally, or resulted in the development of a campfire created by homo erectus --- the equivalent of the nest in other eusocial species.  There is a debate as to whether or not homo erectus had vocal communications ability.   But clearly we can see in this species some of the precursors of human eusociality that both Wilson (September 12, 2012 post) and Martin Nowak (see September 17, 2012 post) addressed. 

The campfire is not merely a nest but it is a location where food, particularly protein-rich meat is cooked and consumed.  This is significant for the larger-brain hominid described above.  Recent studies indicate that increased consumption of cooked vegetation and meat supports larger brains.  The larger brain is not, as described above, merely defined in terms of cranial capacity, but greater neuronal capacity ("neuron rich").  If larger hominids had larger brains, as Lynch and Granger posit, it is plausible that the more successful ("fit") of these larger hominids would put these larger brains to better use than other hominids.  The brain with greater neuronal connections to other parts of the brain and increased neuronal capacity is more likely to do that, and to support those connections and neurons requires increased consumption of cooked vegetation and meat to meet the energy demands of that brain.  It is also plausible that the larger hominid with the larger brain would have to kill larger animals and consume them more frequently than the chimpanzee and other apes and hominids, and to accomplish that feat it is plausible that hunting, killing, and cooking meat in groups is a more successful ("fit") strategy.  To incent that group behavior and longer-term group cohesion for capturing and killing large animals, it is plausible that sharing meat in the vicinity of the campfire would enhance success/survival ("fitness").  Thus, the campfire and brain size are plausibly linked to survival of the hominid phenotype. 

Christopher Boehm notes that most other researchers have taken an ahistorical approach to moral origins among humans, focusing as does E.O. Wilson (September 12, 2012 post) on evolutionary theory as applied to kin selection and group selection or, as does Martin Nowak,(September 17, 2012 post) on mathematical fitness estimations for conditions favoring reciprocal behavior. Boehm offers a historical approach, but to his own credit he, like Charles Darwin, admits to the difficulties in this approach:  we have no written record from the pan troglodytes of 3-6 million years ago, or the austalopethicines of 3.5 million years or the homo habilis or the homo erectus, or even the more recent homo neanderthalensis that followed, about how these extinct species interacted socially (the extent of their within group or other group competition or cooperation), how they communicated.  Furthermore, we have a sketchy, but growing fossil record of these now extinct species, but the fossil record tells us no more about the organization of the brains of these species; all we know is their cranial capacity.  What we do have is evidence of fires, markings on bones, shaped rocks that indicates their use as tools or hunting devices found in the vicinity of the remains of these extinct species and capable of carbon dating, as well as the bones of animals nearby indicating that humans or their predecessors consumed the meat of these animals.  These are true challenges for developing a historical record of what these extinct species were actually like, and Boehm, like Darwin, is forced to describe a history based on its "general plausibility" by providing a working hypothesis, some of which are no more than "glorified hunches, while others may seem them as highly worthwhile leads for future research." 

In addition to the sketchy fossil record described above, Boehm also has at his disposal a body of evidence that can be observed today that is relevant to developing his history:  chimpanzee and bonobo behavior that is presumably similar to their behavior 6 million years ago when the ancestors of genus homo split from pan troglodytes, and the recorded observations of scholars about these species are growing; furthermore, we have a record of observations about a dwindling number of  homo sapiens hunter-gatherer groups developed over the past century to the current period, which behavior is presumably not much different than homo sapiens hunter gatherers who existed 35,000 to perhaps 200,000 years ago.  Based on these observations, Boehm concludes that human hunter gatherers, both now and then, exhibit a behavior that is distinctly different than the behavior of our closest relative, the chimpanzee.  Whereas, the male chimpanzee, is obsessed with dominance and rank and lives in social groups organized hierarchically led by an "alpha male," often displaying in-group aggression against one another and instability in rank, and female chimpanzees less obsessed with rank and dominance, less social, and less aggressive than their male counterparts, the human hunter gatherer of the late Pleistocene, based on modern observations, is characterized by egalitarian relations among persons within small groups, says Boehm.  Something happened in the evolution of the genus pan, to the australopethicines, and genus homo over the 5.8 million year period from the time of split and the emergence of homo sapiens about 200,000 years ago that transformed one species from a hierarchical dominance obsessed social group marked by within group aggression to another species characterized by within-group egalitarianism.  That is the historical trail Boehm seeks to describe in discovering how humans developed a conscience, whereby humans internalize group rules. 

Boehm believes there is a special type of natural selection that he calls "social selection" that involves "the effects of human preferences in choosing others in useful partnerships or in coming down hard on disliked deviants [cheaters]."  His working hypothesis is that at some point in the course of human history, group punishment of cheaters became severe and frequent and affected the human gene pool and ultimately favored human individuals with greater self-control in order to avoid group punishment. Group punishment could have been lethal, Boehm surmises, but it could have involved ostracism or deprivation of what was treated as community property, notably meat.  Whatever the form of punishment invites submissiveness to the group.  The "instrument" of self-control, believes Boehm, is the conscience.  What triggered this development, he submits, is humans embarking on a "new kind of subsistence pattern based on hunting" large animals for food that could only be met by groups.  For these groups to have any kind cohesion required an efficient, equitable sharing of the meat of these large animals.  The obstacle to setting up this egalitarian scenario for a small band of human hunters, Boehm recognizes, is the nature of the ancestral alpha male prone to appropriating the meat of others, which has not altogether disappeared from human nature today.  To achieve egalitarian relations among a small group of human hunters required the threat of force, enforced by the small group.  He believes that this evolutionary trend began around 200-250,000 years ago and culminated approximately 45,000 years ago.  He says this is a "tentative hypothesis," and new archaeological finds and future developments in behavioral genetics could lead to alternative hypotheses. 

Boehm suspects that the step from hierarchically-organized rank-oriented aggressive chimpanzees to egalitarian human hunter-gatherers was motivated by "rank-and-file envy over the perks of alpha bullies, which related to power, food, and sex."  In other words, at some point in time a few million years ago along the trail to homo sapiens, the submissive gradually said we have had enough, we are tired of being intimidated.  The submissive "would have developed some systematic type of collectivized and potentially lethal social control . . . to prevent high-ranking bullies from just naturally monopolizing large carcasses killed by group members and acting as free-riders, when it was the undernourished others in the band who were doing the hard work of hunting."  This type of social sanctioning is observed in modern human hunter gatherer groups in the modern era.  The alpha males are compelled to adapt to the group's will by achieving greater self-control over their egoistic impulses in order to gain greater fitness.  Boehm admits that it is possible that the evolution to egalitarianism began earlier than 200-250,000 years ago when homo sapiens first appeared on the scene (e.g. during the era of homo erectus as early as 1.8 million years ago), but at this point this is even more speculative than the plausible scenario found in the human fossil record.  Boehm points to evidence of carcasses butchered by archaic humans 400,000 years ago that show cut marks on bones that are "chaotic and varied" suggesting that several people did the butchering, consistent with what is observed in chimpanzee and bonobo meat eating scenes.  More recently, about 200,000 years ago there is evidence of cut marks on the bones of animal carcasses that are consistent with a single individual acting as butcher "reminiscent of what takes place with modern hunter-gatherers, where in effect the meat becomes a vigilant band's common property, to be widely shared in a systematic, culturally routinized fashion that averts serious conflict" where the hunters turn the carcass over to a "neutral meat distributor who is uninvolved with the kill," preventing a successful hunter from egoistically controlling the meat.  In contrast, while chimpanzees do share meat, it not a significant part of their diet and the meat does not come from large animals. The strategic motivation for meat sharing among chimpanzees appears to be for the support alliances with other chimps to maintain alpha male dominance within a group rather than support an egalitarian social environment between them. 

We can note several things about Boehm's hypothesis.  The timetable is consistent with the evolution of a larger brain in humans that we know is organized to be more socially responsive to others, both emotionally but also in terms of exercising self-control.  Boehm estimates that human moral origins appeared 35-45,000 years ago.  Interestingly, this suggests that it took about 150,000 - 160,000 years for the larger-brained homo sapiens to evolve their group structures and emotions to support collaborative hunter-gatherer groups. Did the structure of the human brain subtly evolve during this period so that certain homo sapiens with a particular brain structure and types of neurons were selected over other homo sapiens who did not have the same organization? The timetable is also consistent with what we believe occurred with the development of spoken language in humans, which has to be a key to the development of moral rules among humans. Boehm cites evidence of "preaching behavior" among egalitarian hunter-gatherer societies that may have been important to "behaviorally amplify the sympathetic generous tendencies of group members," a behavior that carried over to later hierarchical societies among humans that evolved when settled agrarianism later took root.

Finally, "social selection" is not merely the effect of the suppression of free-riding egoists; rather the intimidation and punishment of deviants acts in combination with "reputational selection."  This is a reference to what we have referred to in the previous posts (see September 17, 2012 post and September 12, 2002 post) as indirect reciprocity.  Simply put, for Boehm, there must be an explanation for why humans extend altruism to non-kin and developed a sense of virtue.  I wonder if we are not over-labeling "selection."  I think Boehm is getting close to saying that there is a gene for altruism, and in fact in his chapter titled "Testing the Selection-by-Reputation Hypothesis" he begins to refer to "altruistic genes" and "genes made for altruism."  I am skeptical of this line of thinking.  Clearly, indirect reciprocity among persons who do not know each other well or know each other at all is based on reputation.  It is a real phenomenon. We often join groups based on reputation. But what nature selects for is emotions and feelings, like attachment and sympathy and empathy, and these emotions in combination with other biological attributes selected by nature end up promoting reciprocal altruism, directly and indirectly.

Finally, what the research described by Christopher Boehm reveals is that the origins of human morality appeared tens of thousands of years before humans created social institutions and hierarchies, including religious and governmental institutions.  Importantly, morality precedes religion and the genetic origins (at least some of the genetic origins) of morality can be linked back to hundreds of thousands if not millions of years ago in other species.  Moral behavior is thus part of nature; it is not owned by religion, nor is it religiously inspired, and it predates the human mind's invention of deities.  Boehm suspects that the origins of religious belief in the brain's capacity for patternicity and agenticity, as described by Michael Shermer (see June 12, 2011 post) probably co-evolved with the origins of morality during the late Pleistocene, but gods, religious institutions, and the co-opting of morality by religious institutions came later, when humans began creating permanent communities as they transformed from hunter-gatherers to agrarian life and domestication of animals.

Martin A. Nowak, SuperCooperators (2011)

In 2010, Martin Nowak collaborated with biologist Edward O. Wilson (see previous post) and mathematician Corina Tarnita in publishing an article in Nature entitled "The Evolution of Eusociality." The following year, Nowak followed the Nature article with SuperCooperators; two-years later, Wilson followed the Nature article with The Social Conquest of the Earth.  The cornerstone of the Nature article was its criticism of the inclusive fitness theory, developed by William Hamilton and others, that became the mathematical foundation of kin selection in evolutionary analysis. Kin selection theory became the basis on which the presence of altruistic behavior in nature, a phenomenon noted by Darwin in The Origin of Species, could be explained in evolutionary terms.  One would have thought from the Nature article that Nowak and Wilson were on the same page in terms of their analysis of evolution and cooperation, but the fact that they wrote separate follow-on books reveals significant differences.  While Wilson creates controversy by announcing that he finds little additional value in kin selection theory for evolutionary analysis, Nowak acknowledges the detractors that responded to the Nature article and concludes that kin selection still has some explanatory value.

The discussion of group selection theory and multilevel selection with respect to the social insects in The Social Conquest of the Earth closely follows the summary of "a full theory of eusocial evolution" in the Nature article:  "We suggest . . . the following may be recognized:  (1) the formation of groups.  (2) The occurrence of a minimum and necessary combination of pre-adaptive traits, causing the groups to be tightly formed.  In animals at least, the combination includes a valuable and defensible nest. (3) The appearance of mutations that prescribe the persistence of the group, most likely by the silencing of dispersal behavior.  Evidently, a durable nest remains a key element in maintaining the prevalence.  Primitive eusociality may emerge immediately due to spring-loaded pre-adaptations.  (4)  Emergent traits caused by the interaction of group members are shaped through natural selection by environmental forces.  (5)  Multilevel selection drives changes in the colony life cycle and social structures, often to elaborate extremes. *** We have not addressed the evolution of human social behavior here, but parallels with the scenarios of animal eusocial evolution exist, and they are, we believe, well worth examining."

In their separate books, both Wilson and Nowak address "the evolution of human social behavior" not addressed in the Nature article, but they take divergent paths.  Wilson starts to head down a path I wish he had developed further.  To determine what evolved that made us humans, he begins by asking "What is human nature?"  He suggests that the place to look is "in the rules of development prescribed by genes, through which the universals of culture are created."  Human nature, he says, is the "inherited regularities of mental development common to our species.  They are epigenetic rules, which evolved by the interaction of genetic and cultural evolution that occurred over a long period in deep prehistory.  These rules are the genetic biases in the way our senses perceive the world, the symbolic coding by which we represent the world, the options we automatically open to ourselves, and the responses we find easiest and most rewarding to make. . . They determine the individuals we as a rule find sexually most attractive.  They lead us differentially to acquire fears and phobias concerning dangers in the environment, as from snakes and heights, to communicate with certain facial expressions and forms of body language, to bond with infants; to bond conjugally; and so on across the wide range of other categories of behavior and thought."  This is an important statement, but Wilson does not flesh it out, and he trips when he adds, "the rules of physiological development are not genetically hardwired."  As Sean Carroll's Endless Forms Most Beautiful, The New Science of Evo-Devo explains, the developmental processes of different organisms are genetically determined, including the post-natal development of the organism, which in the case of humans goes on for many years.  Wilson is simply wrong when he says that physiological development is "not beyond conscious control, like 'automatic' behaviors of heartbeat and breathing."  He is wrong when he suggests that physiological development is completely "learned."  Yes, there is a point when learning and culture become more influential, but as early (infant) child development research reports, the earliest form of social communication, mimicry, is instinctive, and it is not learned.

Wilson's reference to "physiological development" may simply be semantical error.  Physiology broadly refers to  "a branch of biology that deals with the functions and activities of life or of living matter (as organs, tissues, or cells) and of the physical and chemical phenomena involved—compare anatomy, morphology."  Sean Carroll's discussion of evolutionary developmental biology focused primarily on morphology, although physiology is understood in its broader context as applicable to everything about living matter that has a genetic correlate. That would include the human brain and the neurosensory system.  Wilson is  thinking about something different than physiology.  He is contemplating behavioral epigenetics, and refers to our innate predispositions to learn and make one choice over another. This is why understanding the human brain and the neurosensory system that feeds the human brain is critical to understanding human nature.  Nor surprisingly, many posts on this blog are devoted to this understanding.  Specifically, human behavior is not genetically determined, as social insect behavior might be genetically determined, but our nature has effectively set us up to receive information (learning, culture) in such a way that is more likely to cause us to behave one way rather than another.  An example of this "predisposition" includes incest avoidance; we have a "bias" against sexual relations with those we have grown up in the same household. 

In terms of social behavior, as I previously mentioned in the prior post I do not think we can understate the role of human memory --- unique in the animal kingdom --- in the evolution of culture.  I also do not think we can understate the role of feelings and emotions either, and my surmise is that there is more than a predisposition here:  human feelings and emotions are hardwired, and they likely contribute substantially to a number of our biases and predispositions.  For example, feelings such as blushing  are associated with social emotions such as shame and embarrassment. These emotions are universal among normal humans.  It is surmised that blushing may have evolved as a means of avoiding conflict by reducing the possibility of deception.  The person who witnesses another blush knows the reaction is authentic and that the person acknowledges he is troubled by what has happened.  Disgust is another social emotion, likely to have evolved as a part of a physical response to offensive foods, is universal among normal humans.  Wilson only briefly alludes to these basic social emotions, but significantly culture has evolved to exploit these emotions so the emotion can be triggered differently among different cultures.   Nudity, for example, may trigger blushing in one culture,and no response in another.  Fear, which Wilson briefly discusses, is another emotional response that has consequences for social behavior, is also exploited by culture.  Feeling and emotion are central components of a biologically based understanding of morality, altruism and cooperative behavior.  These emotions are also related to facial expressions that builds cooperative bonds, as observed by Paul Ekman and Dacher Keltner and reported in the discussion of Keltner's Born To Be Good:  The Science of a Meaningful Life (see July 16, 2010 post):

"'Emotions are involuntary commitment devices that bind us to one another in long-term, mutually beneficial relationships,' Keltner says. Emotions are communicated through several sensory means: visually through facial expressions, which Keltner documents based on his own research and that of his teacher and mentor, Paul Ekman, explaining how muscles in the face are linked to and controlled by neural pathways in the brain that make them reliable indicators of emotion. In facial expression, we recognize embarrassment, which signals our moral sense of wrongdoing and respect for the judgment of others. In facial expression, the smile signals friendly intent and affection among peers and movement toward cooperation and intimacy. In facial expression, laughter triggers mirror neurons in the brains of others that builds cooperative bonds between one who laughs and the other who hears the laugh. Keltner tells us that teasing is not the same as bullying, and is a type of playful communication designed to ferret out another's commitments that bolsters social life. Emotions are communicated through touch, and the skin, our largest sensory organ, evolved to be an important part of social communication among humans and their predecessors."

Emotions also shape our reasoning, undermining the notion that we are purely rational animals. 
(See April 8, 2011 post): 

"Hume's treatment of emotions is not radically different than Damasio's, because Hume's catalog of emotions largely fall under the label of what Damasio refers to as the 'social emotions,' which Damasio believes are of recent evolutionary vintage, some of which may be exclusively human. For both Hume and Damasio, emotions shape our reasoning: 'rational' choice, if you will, is not independent of or from emotions and feelings. Compassion (empathy/sympathy) is one of those social emotions, and compassion, along with admiration, is critical in building a social construct in Damasio's view. And so it is with Hume, as Part III (On The Morals) states that sympathy with public interest is the source of moral approbation, and ultimately reciprocal promise-making behavior and principles of justice: 'sympathy is a very powerful principle in human nature, that it has great influence on our taste of beauty, and that it produces our sentiment of morals in all the artificial virtues.'"

Nowak, in contrast, is less concerned with the biological basis of social behavior, and he is more concerned with the conditions that make social cooperation more likely or less likely than not, and whether those conditions can be mathematically modeled (a game theoretic approach) and tested.  Nowak finds that there are five "mechanisms" that explain whether social behavior is a likely trait that overcomes natural selection's inherent tendency to favor the individual pursuit of self-interest (cheating, defection).  "[N]atural selection favors defectors [over cooperators] . . cooperators have a lower fitness than defectors in a well-mixed population.  As a consequence, as that population evolves, natural selection slowly increases the abundance of defectors until every last one has been exterminated.  This is the 'wrong' outcome, because a population of cooperators has a higher productivity (higher average fitness) than a population of defectors.  Hence, in this particular case natural selection does not achieve the highest fitness but actually destroys what would be best for the entire population.  To favor cooperation, natural selection needs help.  It needs mechanisms for the evolution of cooperation. . . My work show how cooperation arises out of competition, even though the two are locked together in ceaseless conflict.  The collective effort of society depends in part on suppressing the ability of the individual to mutiny and defect.  The same goes for rebellious cells, chromosomes, and genes.  Like day and night, or good and bad, cooperation and competition are forever entwined in a tight embrace."

The first of the five mechanisms of cooperation is direct reciprocity (backscratching) arising out of repetitive interaction.  I will do a favor for another because I expect to encounter that person again and he will repay the favor.  The second mechanism is indirect reciprocity, a reference to the reputation of the person or group (I will do you a favor, and by my reputation someone else will do me a favor).  This type of reciprocity occurs without direct contact.  The other person may be on another side of town or on the other side of the world.  Indirect reciprocity relies heavily on communication to establish a reputation and language capacity is therefore important.  The third mechanism is spatial selection, where natural selection favors individuals who form networks that help each other. The fourth mechanism is multilevel selection, where natural selection favors groups who are more successful in cooperating than other groups. The fifth mechanism is kin selection.  With these five mechanisms of cooperation, "natural selection ensures that we are able to get more from social living than from the pursuit of a solitary, selfish life." 

According to Nowak, what makes humans unique is that we are the only species on Earth that draws support from all five mechanisms of cooperation.  We are the only species that "can summon the full power of indirect reciprocity, thanks to our rich and flexible language."  That makes us "supercooperators."  He adds, "We are now subject to an evolutionary dynamic that can detach itself to some degree from its genetic basis, from chemistry, genes, and DNA.  This is cultural evolution, which involves learning, and explains why we are so devastatingly successful.  As a result, the way the human brain evolves is utterly different from the evolution of any other biological structure that has ever existed.  The architecture of the brain changes every time we talk to another person.  We are able, in turn, to impose structural changes on the way the listener's brain is wired.  The next time you listen to another person, remember that you have permanently changed the wiring of your brain and will do this every time you memorize a moment, no matter how fleeting."  This remark recalls the discussion of how fragile memory is in the September 20, 2011 post discussing Daniel Schacter's The Seven Deadly Sins of Memory.  Equally, however, Nowak demonstrates that notwithstanding a different attitude toward kin selection theory, he really is on the same page with Edward Wilson.  "I do not restrict the use the term 'natural selection' to genes alone.  Depending on whether we talk about cells, animals, or people, reproduction can be genetic or cultural."  If we are speaking in terms of the fact that everything in life is reducible to a unit of information, I would agree that culture can be transmitted.  (See August 15, 2011 post, August 17, 2009 post). And yes, cultures can die and disappear as a result of changes in the environment, as we saw in Jared Diamond's Collapse (see August 12, 2012 post), and Nowak echoes Diamond's concerns when he express concerns about "mankind teetering on the brink of several possible catastrophes of its own making," including nuclear conflagration and the ultimate "Tragedy of the Commons," global warming, which he believes will force humans to enter a new chapter of cooperation.  The question, of course, is how long will take for humans to establish that level of consensus (see August 12, 2012 post).  But I would echo Frans DeWaal:  evolving culture in humans will not contradict what has evolved biologically, it will only support what evolved biologically.