Howard French's Atlantic article does a good job summarizing Wilson's main theory as laid out in The Social Conquest of Earth: that sociality among animal species evolved not because of the theory generally accepted for the last half-century or so, known as "kin-selection theory" (that is, that cooperation between species members arises because of close genetic connection between group members) but rather that eusocial behaviors have (only very rarely) emerged in animal species as a result of an evolutionary process.
Wilson also examines the development of kin selection theory and how his views on it have evolved over the years as new evidence has come to light. With the arrival of the theory of multilevel natural selection as a more general theory, and with the breakdown of kin selection theory's basic principles, he argues that it is time for evolutionary biology to leave the idea of kin selection behind entirely. I'm sure that it won't go without a fight, as it still has a wide variety of proponents in the field, but it will sure be a fascinating process to watch (and just speaking intuitively, since I don't know the technical literature very well at all, it seems to me that Wilson probably has the better of the argument).
The process toward sociality as laid out by Wilson consists of five distinct stages, the final two of which have been reached only in certain insects like honeybees and army ants (group formation; "occurrence of a minimum and necessary combination of preadaptive traits in the groups, causing the groups to be tightly formed"; "appearance of mutations that prescribe the persistence of the group"; group-level selection by environmental forces; and changes in the life cycle based on group-level selection, sometimes leading to the development of a superorganism). A key step along the path to sociality, Wilson argues, was the creation of a defensible nest.
Much of The Social Conquest of Earth is given over to fascinating and sometimes quite technical accounts of how these processes developed in animal species, from certain types of shrimp to termites to leafcutter ants and aphids, and then how human societal development can be traced back to those same processes. "The key to the origin of the human condition is not to be found in our species exclusively, because the story did not start and end with humanity. The key,"Wilson argues, "is to be found in the evolution of social life in animals as a whole" (p. 109). As to why humans have emerged to be the dominant species they have, Wilson suggests it's simply because Homo sapiens is the only species to have made "every one of the required lucky turns": land-based existence, large body size, grasping hands, bipedal movement, meat-based diet, organized groups, control of fire, development of central campsite "nests," division of labor, &c.
The human brain, Wilson writes, "had to become highly intelligent and intensely social ... selfish at one time, selfless at another" (p. 17). He argues that humanity is faced with an unsolvable dilemma, rooted deeply in our evolutionary history: that because human beings are subject to both individual- and group-level impulses and urges at all times, we are literally at war with our selves. Altruism and group welfare are a part of us, but at the same time, so are selfish desires. The human species is, Wilson writes, "an evolutionary chimera, living on intelligence steered by the demands of animal instinct. This is the reason we are mindlessly destroying the biosphere and, with it, our own prospects for permanent existence" (p. 13).
Some of the consequences Wilson sees in the ever-present human struggle between individual- and group-level selection include intense inter-group competition; unstable group composition; "an unavoidable and perpetual war ... between honor, virtue, and duty ... and selfishness, cowardice, and hypocrisy"; "quick and expert reading of intention"; and, in fact, much of culture itself (p. 56). What humans create as art, religion and social behavior, Wilson maintains, springs from this tension between individual and group selection.
In the last hundred pages or so of The Social Conquest of Earth, Wilson turns to human culture. Drawing on his immensely broad knowledge of scholarship across an impressive variety of fields (from linguistics to history to religion to art and beyond), Wilson lays out the processes by which human beings came to develop what we know today as culture (from language to religion and beyond). He begins by bursting a bubble or two: "The explosion of innovations that lifted humanity to world dominance surely did not result from a single empowering mutation. Even less likely did it come as some mystic afflatus that descended upon our struggling forebears" (p. 225). Wilson uses the term "gene-culture coevolution" to describe the process by which cultural practices developed and were passed down through the "genetic predisposition of individuals to select and transmit through culture one out of multiple options possible" (p. 203). This idea, he writes, offers a way to connect the natural sciences, social sciences and the humanities; understanding how both genes and group selection dynamics have influenced and continue to influence cultural practices can help us as a species explain why we do some of the things we do. "The naturalistic understanding of morality does not lead to absolute precepts and sure judgments, but instead warns against basing them blindly on religious and ideological dogmas," Wilson writes (p. 252).
Indeed, Wilson's harshest criticism in the book is reserved not for those who continue to embrace kin selection theory, but for what he sees as "dogmatic ethics gone wrong for lack of knowledge" (p. 253). Two particular examples are bans on contraception and homphobia. The first, promulgated by Paul VI in 1968, fails to account for all the evidence that non-reproductive sexual activity plays key roles in human biology. And homophobia, Wilson writes, is just as wrong: homosexuality, a trait influenced by heredity, occurs too frequently to be due to genetic mutation, and it is widely accepted that "if a trait cannot be due solely to random mutations, and yet it lowers or eliminates reproduction in those who have it, then the trait must be favored by natural selection working on a target of some other kind. For example, a low dose of homosexual-tending genes may give competitive advantages to a practising heterosexual. Or, homosexuality may give advantages to the group by special talents, unusual qualities of personality, and the specialized roles and professions it generates. There is abundant evidence that such is the case in both preliterate and modern societies. Either way, societies are mistaken to disapprove of homosexuality because gays have different sexual preferences and reproduce less. Their presence instead should be valued for what they contribute constructively to human diversity. A society that condemns homosexuality harms itself" (p. 253-4).
Organized religion, Wilson argues here, is a simple expression of tribalism, with the "illogic" of religious belief not a weakness, but a strength, in that it serves to bind the group's members together to the exclusion of outsiders (unless they can be persuaded to join). Creation stories, genesis myths and even the "phantasmagoric elements" shared between the world's religions are all explainable as cultural relics (and/or as the result of hallucinogenic drugs; this, he suggests, is a much more plausible explanation for John's visions as recorded in the Book of Revelation than that any such thing actually happened).
By understanding that the struggle inherent in multilevel selection "is the fountainhead of the humanities," Wilson writes, we can better explain our cultural artifacts, and perhaps even rise above what they have wrought in today's society. In the final chapter, "A New Enlightenment," Wilson calls for humanity to overcome the cultural shackles that bind us into tribes and come together as a species, before it is too late, to preserve the planet, the only one we're ever going to be able to live on. The processes of human-wrought climate change and the "obliteration" of Earth's biodiversity must be arrested, Wilson urges, and in order to make that possible:
"It will be useful in taking a second look at science and religion to understand the true nature of the search for objective truth. Science is not just another enterprise like medicine or enginerering or theology. It is the wellspring of all the knowledge we have of the real world that can be tested and fitted to preexisting knowledge. It is the arsenal of technologies and inferential mathematics needed to distinguish the true from the false. It formulates the principles and formulas that tie all this knowledge together. Science belongs to everybody. Its constituent parts can be challenged by anybody in the world who has sufficient information to do so. It is not just 'another way of knowing' as often claimed, making it coequal with religious faith. The conflict between scientific knowledge and the teachings of organized religions is irreconciable. The chasm will continue to widen and cause no end of trouble as long as religious leaders go on making unsupportable claims about supernatural causes of reality" (p. 295).
It's not too late for humanity, Wilson concludes, ever optimistic, but to save our planet, and ourselves, will require a tremendous amount of effort and a recalibration of humanity's priorities on a grand scale. We must, he argues, rely on "an ethic of simple decency to one another, the unrelenting application of reason, and acceptance of what we truly are" (p. 297).
I can't say that I entirely share Wilson's faith in humanity. While I certainly find his theory as outlined here quite compelling, I also happen to share his belief in rational, science-based thinking, and too many people out in the world don't (witness the state of American politics today, where denial of science-based realism is worn as a badge of honor by the leading members of a major political party). I fear that it will take a catastrophic event of, dare I say, Biblical proportions, to bring many people around to the view that comes so naturally to Wilson and, likely, to many of those who read his works.
Wilson's writing draws the reader in quickly: here's a representative quotation from near the beginning of the book: "Humanity today is like a walking dreamer, caught between the fantasies of sleep and the chaos of the real world. The mind seeks but cannot find the precise place and hour. We have created a Star Wars civilization, with Stone Age emotions, medieval institutions, and godlike technology. We thrash about. We are terribly confused by the mere fact of our existence, and a danger to ourselves and to the rest of life" (p. 7). He's able to summarize very technical scientific processes and make them understandable to those of us not so well-versed in such things, and while sometimes it's handy to have a dictionary about (a few of the new words I jotted down as I read: vicariant, anastomosed), that makes reading books like this all the more enjoyable.
A challenging, deeply meaningful and extremely important book, sure to provoke much argument from many different corners, The Social Conquest of Earth is the sort of book that doesn't come around very often at all. Anyone with an interest in the consilience between intellectual disciplines and/or in the roots of human culture generally should read it, and I hope the conversations it sparks will be sustained and fruitful.