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.