Monday, September 17, 2012

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. 

Wednesday, September 12, 2012

Edward O. Wilson, The Social Conquest of Earth (2012)

We tend to think of evolution in terms of a struggle, a "competitive struggle" in which natural selection favors certain genes, or a collection of genes in a particular organism for continued reproduction and survival.  It is adaptation, however, not necessarily competition, that explains survival, and evolutionary theorists commonly explain adaptation in terms of self-interest.  In Richard Dawkins' view, for example, genes are "selfish."    In nature, however, evolution has favored a rare condition,  "eusociality" in a handful of species, who in many respects have come to dominate the earth.  As described by biologist Edward O. Wilson, eusociality refers to the "condition of multiple generations organized into groups by means of altruistic division of labor."  The social insects --- wasps, ants, termites, bees, and a small number of other insect species --- are the most prominent examples of eusociality.  The biomass of ants, for example, exceeds over half of all insects as well as the biomass of all non-human terrestrial vertebrates.  Another prominent example, yet very different from the social insect, is the homo sapien. 

Eusociality is characterized by a high level of cooperation, but it is important to note that cooperation is only a necessary, but not a sufficient condition for eusociality.  We can think of many other examples in the animal kingdom, including symbiosis, multiple forms of reciprocal behavior, parenting, that do not rise to "multiple generations organized into groups by means of an altruistic division of labor."  The definition of eusociality is a tight definition; it is not intended to capture all cooperative behavior in the animal kingdom that might be deemed "social."  Eusociality does not describe herds, packs, dens, prides, or other groups animals who exhibit social behavior, because their social condition is not composed of multiple generations or their means of organization does not constitute an altruistic division of labor.  Our closest living species, the chimpanzee, who exhibits social behavior (see November 9, 2010 post and June 17, 2010 post)  is not considered eusocial. 

In the world of social insects, the group is organized around the nest (or hive).  In all of the examples of species that have attained eusociality, altruistic cooperation, says Wilson, protects a "persistent, defensible nest from its enemies, whether predators, parasites, or competitors," which sets the stage for members of a group belonging to more than one generation to divide labor in a way that sacrifices at least some of their selfish interests to the group.  Importantly, multiple generations within the nest stay with the nest.  They do not disperse.

While it is not yet proven, Wilson believes that eusociality in the social insects is genetically driven by a gene that silences the insect brain's program for dispersal and prevents the mother and her offspring from dispersing to create new nests, allowing natural selection on the rest of the genome to effectuate more complex forms of social organization.  This occurs, says Wilson, because natural selection impacts not only the genotype (gene selection), but it also operates on groups within a species as well (group selection).  This is the multi-level selection thesis previously discussed in the prior posting on Holldobler and Wilson's Superorganism (see November 4, 2009 post).  The new twist in The Social Conquest of Earth is Wilson's declaration that kin selection, a form of group selection, can no longer be defended because its mathematical underpinning, inclusive fitness theory, had been debunked in a 2010 article co-authored by Wilson, Corina Tarnita, and Martin Nowak.  The work of Bill Hamilton and George Price (see October 13, 2010 post), he contends, no longer contributes much to evolutionary analysis. 

While multilevel selection remains a significant storyline in The Social Conquest of Earth, the biology of eusocial insects is merely a starting point for the discussion here.  Wilson's focus is the homo sapien, humanity, and human nature, explaining his views of how eusociality evolved in homo sapiens.   In contrast to the social insects, humans do not congregate in a nest.  In contrast to the social insects, humans do disperse.  But humans do build and maintain social communities comprised of multiple generations and, Bernard Mandeville's Fable of the Bees notwithstanding (see January 30, 2010 post),  humans are organized into groups by altruistic division of labor.  For Wilson,  the social evolution of humans is not attributable to a single or "major" event such as the development of enlarged brains or bi-pedal mobility, but can only be understood in terms of prehuman adaptations in ancient species and adaptations that distinguish humans from other hominids, evidence from human archaeology, and the co-evolution of human culture, all of which have come to define "human nature." Wilson is a proponent of the "dual inheritance theory." For Wilson, a key event in human history is technological:  the mastery of fire.  With the ability to control fire, campfires are created and the campfire, in Wilson's view, is the homo sapiens' counterpart of the insect nest.  Campfires are the venue that facilitates the sharing of food, and this is the magnet that draws homo sapiens into a cooperative environment.

In my November 4, 2009 post, I commented on Holldobler and Wilson's discussion of multilevel selection as follows:  "However powerful the evidence for the superorganism is and the multilevel selection model, the truth remains that the critical unit of evolution is the gene."  I made have overstated the uniqueness of the gene in making this statement and uninentionally sublimated the individual:  after all, it is the individual (a collection of genes) that reproduces.  A comment I made in the November 9, 2010 post discussing Frans DeWaal's The Age of Empathy seems extremely relevant:   "Our capacity for cooperation, altruism, and other social instincts is certainly biological, and it is a product of evolution. We have much to learn about what makes us human from learning about the behavior of other species from which humans evolved as we do from observing our own behavior. This is De Waal's primary thesis. And this thesis is no stranger to this blog and previous posts, including De Waal's own The Ape and the Sushi Master (June 17, 2010 post), Oren Harman's The Price of Altruism (October 13, 2010 post), Dacher Keltner's Born to Be Good (July 16, 2010 post), Holldobler and Wilson's The Superorganism (November 4, 2009 post), Michael Gazzaniga's Human (September 27, 2009), Marco Iacobonni's Mirroring People (September 18, 2009 post), and Christine Kennealy's The First Word (August 31, 2009 post)."  Natural selection operates on what is biological or chemical; while culture undeniably "evolves," natural selection as we understand it does not operate upon culture.  If culture is going to be successful, it is because it supports what natural selection favors. As Frans DeWaal explains in the The Ape and The Sushi Master:   "Although the relation between culture and nature can be tense, culture mostly tries to get along with nature." Culture cannot change nature; culture can evolve behavior to act consistently with nature. For example, the incest taboo - an avoidance of sex among family members, long a cultural regulation, is now known to be a form of behavior in the primate world that appears to be innate in some aspects (an aversion rather than an avoidance) and perhaps learned in other respect. (See June 17, 2010 post)."  Group selection and multilevel selection are not settled theories, and Wilson's rejection of kin selection is contested by others in the field.

Wilson's discussion of "group selection" suggests that evolution operates at the level of a group within a species.  Thus a "group" might be a nation or a religious group or an ethnic group in the case of humans, and here I part company with Wilson .  These are cultural groups, and natural selection does not operate upon culture.  When I thought about how I would respond to Wilson's discussion here, I realized I had already said in my discussions of Frans DeWaal's The Age of Empathy (November 9, 2010 post) and The Ape and the Sushi Master (June 17, 2010 post)  what I want to say (and what DeWaals has to say) about the linkage between genes and culture in those posts.  Here is a snippet from the June 17, 2010 post:

"Culture and genetics have one thing in common --- the transmission of information: in the case of genetics information is transmitted by biological/chemical means, in the case of culture it is transmitted by social means. 'This is not to say that both forms of behavioral inheritance --- the one traveling across time via genotypes, the other via phenotypes --- should not or could not be conceptually linked. Ironically, the Lamarckian idea that acquired characteristics can be inherited has found its realization not in the physical characteristics he was thinking of, but in behavior. Genetic predispositions feed into culture, culture affects survival, and survival and reproduction determine which genotypes spread in the population. In other words, there exists a dauntingly complex interplay between genetic and cultural transmission. Brave and inspiring attempts at a theory of dual inheritance, or co evolution, have been made, without, however, in any way confusing the two processes.'"  Wilson confuses the two processes.  I would have liked to see in his discussion of human evolution and our predisposition to social behavior a more biologically-based discussion of the neurological system and human child development, such as that in the November 9, 2010 post about The Age of Empathy: 

"At the biological core of our humanness is the limbic system, which, from an evolutionary perspective, is one of the oldest parts of our neural network in the human brain. It is a part of the brains of other species as well. Antonio Damassio identifies the limbic system as a critical regulator of feelings and emotions in The Feeling of What Happens, and it is central to understanding human consciousness. De Waal says the limbic system allows emotions such as affection and pleasure, and paved the way for family life, friendships, and other caring relationships. Other parts of our neural network allow us to store memories of these feelings and emotions and allow us to recall the context in which we previously experienced them and then to "understand" them. A key line here is De Waal's statement, "Bodily connections come first --- understanding follows." Mirror neurons, as described in Iacobonni's Mirroring People (September 18, 2009 post), are active in these other parts of the neural network known as the brain that allow us to "read" the minds of others, enabling us to connect with others, and facilitate the the experience we call empathy. "De Waal calls this emotional contagion: seeing another's emotions arouses our own emotions, and then we build "a more advanced understanding of another's situation." Later, he adds, "Empathy engages brain areas that are more than a hundred million years old. The capacity arose long ago with motor mimicry and emotional contagion, after which evolution added layer after layer, until our ancestors not only felt what others felt, but understood what others might want or need."

"True to his dualism, just as De Waal recognizes that emotional contagion probably starts immediately with the mother-child relationship and that early communication fosters a bond, a second phase begins just months later in the course of child development when the child begins to develop a sense of self. And empathy, De Waal believes, "requires both mental mirroring and mental separation." The former occurs when we see another person in a particular emotional state. The latter occurs when we parse our own emotional state from the other, and this allows us to "pinpoint the actual source of our own feelings." De Waal attributes our dualism to the existence of VEN cells in the brain --- Von Economo neurons --- that differ from other neurons and are unique to humans and their recent ancestors. Physically, VEN cells are long and spindle-like and reach deeper into the brain. Research shows that when parts of the human brain that contain these cells are damaged, behavior is marked by a loss of perspective-taking, empathy, embarrassment, and future orientation. Besides humans and certain apes, these cells are also found in dolphins, whales, and elephants, where behavioral research shows they have the capacity for empathy that is not found in other species."

Some of this is touched upon by Wilson, but what is touched upon deserves elaboration and much is missing from The Social Conquest of Earth.  Yet these biological attributes of homo sapiens are the products of natural selection in humans and they specifically relate to our ability to act cooperatively and altruistically:  the neurobiology behind feelings and emotions (see April 8, 2011 post), the neurobiology behind memory (see April 8, 2011 post and November 6, 2011 post, and September 20, 2011 post), the neurobiology behind our sensory system and our ability to communicate and our capacity for storytelling (see October 25, 2011 post, September 27, 2009 post, and August 31, 2009 post), and the biology of human development.  For example, we cannot underestimate the role of human memory (including the failings of memory, see September 20, 2011 post) in evolving a human culture, and several prior posts have addressed this subject in one way or the another.  (See September 28, 2010 post, September 9, 2010 post,  and August 15, 2011 post) Wilson merely summarizes these attributes when he notes:

"What catapulted Home sapiens to this level?  Experts on the subject agree that increased long-term memory, expecially that put into working memory, and with it an ability to construct scenarios and plan strategy in brief periods of time, played the key role in Europe and elsewhere, both before the African breakout and afterward.  What was the driving force that led to the threshold of complex culture?  It appears to have been group selection.  A group with members who could read intentions and cooperate among themselves while predicting the actions of competing groups, would have an enormous advantage over others less gifted. . . Morality, conformity, religious fervor, and fighting ability combined with imagination and memory to produce the winner."

These are the human attributes that are genetically determined by evolution, and they are the biological basis of humanity.  Our social instincts are derived from these biological attributes.

Notwithstanding my conclusion that much is missing from The Social Conquest of the Earth, Wilson's discussion of the origins of religion and organized religion and the origins of the creative arts are brilliant.  These subjects too have been the topics of prior posts.  (See January 14, 2012 post, February 4, 2012 post, February 15, 2012 post, and June 12, 2011 post).