The big history of human social evolution from the Paleolithic to the present shows two great revolutions. In the agrarian revolution, human beings moved from foraging to farming (beginning about 10,000 years ago). In the modern revolution, human beings moved from agrarian states to industrialized commercial republics (beginning about 500 years ago and accelerating about 200 years ago into the Industrial Revolution).
In Abraham Lincoln's "Lecture on Discoveries and Inventions, his "Address to the Wisconsin State Agricultural Society," and in his meeting with some American Indian chiefs, Lincoln laid out his conception of cultural evolution as moving through three stages of society--from foraging societies to agrarian societies to societies based on commercial exchange and free labor. Thus did Lincoln anticipate David Christian's account of deep history.
These social revolutions certainly required evolutionary changes in human culture--changes in cultural ideas and institutions. But did they also require evolutionary changes in human biology--changes in the genetic propensities of human nature? Many biologists (like Stephen Jay Gould and Ernst Mayr) and evolutionary psychologists (like John Tooby and Leda Cosmides) have said no, because they assume that human biological evolution stopped sometime shortly after our ancestors expanded out of Africa 40,000 to 50,000 years ago. But recently, Gregory Clark (A Farewell to Alms), Gregory Cochran and Henry Harpending (The 10,000 Year Explosion), and Nicholas Wade (A Troublesome Inheritance) have marshaled the evidence and reasoning for the claim that these social revolutions required genetic changes as well as cultural changes.
I find the evidence too skimpy and the reasoning too speculative to prove the case for genetic evolution in these two social revolutions. But as I suggested in a post a few weeks ago, one of the most plausible lines of reasoning for the genetic explanation is based on the research of Dmitry Belyaev in showing how the selective breeding of silver foxes in Siberia has made them as tame as dogs in only 40 years. This suggests that a genetic change in human behavioral propensities could occur in a human population if the social circumstances create a selective pressure for tameness or less violent and more cooperative behavior. Human beings might have evolved by self-domestication to be genetically inclined to the bourgeois virtues that support liberal regimes.
The crucial feature of the transition from foraging to farming was the domestication of animals and plants. This was the ancient beginning of biotechnology, because farmers were artificially selecting plants and animals to satisfy human desires in ways that created new species. Without understanding genetics, they were engaging in the genetic manipulation of organisms to make them more useful to human beings.
It's good to keep this in mind while listening to those today who oppose biotechnology as a modern human disruption of the natural order of things. Contrary to what people like Leon Kass say, the use of biotechnology to master nature for the relief of the human estate was not an invention of modern science, because it began 10,000 years ago, and it's the most important turn in human history.
An important part of Darwin's argument for his theory of natural selection was the analogy between natural selection and artificial selection. Just as plant and animal breeders select those naturally heritable traits they favor and thus over time create new varieties and species that are adapted to human needs, so does natural selection favor some heritable traits over others and thus creates new species that are adapted to their environment. This was the argument for the first chapter of The Origin of Species (1859) and for the Introduction to his massive two-volume book The Variation of Animals and Plants Under Domestication (1868).
Of the 146 large mammalian species of animals, only 15 have been domesticated. Apparently, most animals lack the genetic potentiality for domestication. So, for example, while horses were one of the first species to be domesticated, zebras have resisted all attempts to domesticate them.
In what might have been the first domestication of an animal, wolves (Canis lupus) evolved into dogs (Canis familiaris). Actually, this might have occurred through a combination of natural selection and artificial selection. Any attempt of prehistoric people to artificially select wolves for domestication would have created a cultural niche to which wolves might have become adapted by natural selection.
Similarly, we must wonder whether our human ancestors were domesticating themselves by creating new cultural niches--first farming life and large settlements and then modern commercial regimes--to which they became adapted by both artificial and natural selection. If this is what happened, then we might explain liberal political thought as evolutionary niche construction: liberal norms and institutions become a cultural niche favoring some behavioral traits over others, and if these traits are genetically influenced, then human beings could evolve genetically to be better adapted to this liberal niche. If so, then classical liberalism is an exercise in human biotechnology.
But for this to happen, genetic evolution would have to occur over rather short periods of time by evolutionary standards--over thousands or even hundreds of years. We generally assume that that's the speed of cultural evolution but not genetic evolution.
Belyaev showed that a selective-breeding program could bring about such genetic evolution in a few decades. He believed that the domestication of dogs had been selection for the behavioral trait of tameness. To test this, he set out to domesticate the silver fox (Vulpes vulpes), an animal that had never been domesticated. He selected foxes for tameness and against aggression. After 40 years, and 30 to 35 generations of selection, he had created foxes that were doglike in their friendliness to human beings.
Belyaev and his colleagues also bred another line of foxes for their aggressiveness. Now, one can see the contrast between those foxes bred to be doglike in their tameness and those bred to be wolflike in their aggressiveness. They have done the same thing for rats.
Domesticated animals show a common suite of traits that Darwin identified and that now can be explained as pedomorphosis or neoteny--the retension of juvenile traits by adults, which include behavioral traits like submissiveness and gregariousness.
Since we do not know exactly how genes influence behavior, we cannot prove that there has been genetic evolution here that explains behavior. But we can make a plausible case that there are genes that influence the development of the brain and nervous system so as to change the neurochemical and hormonal mechanisms that underlie behavioral propensities. Therefore animals can evolve genetically to be better adapted behaviorally to their cultural environment, and this should be as true for human beings as for other animals.
If this is so, then it's possible that the cultural evolution from foraging to farming and then into modern liberal commercial societies was also a genetic evolution. In the first step, settling into farming communities with large populations required breaking away from the tribalism of foraging bands bound together by kinship ties, so that people became less violent and fearful of outsiders. In the second step, people had to adopt the bourgeois virtues of modern commercial society--self-control, deferral of gratification, industriousness, tolerance of strangers, and willingness to engage in the extended order of global trade and cosmopolitan mobility.
The recent electoral victories in Europe for the right-wing, anti-immigrant political parties is a reminder that this evolution of human political psychology away from ancient tribalism and towards liberal cosmopolitanism has not yet fully succeeded. The importance of evolving beyond tribalism for the move from "extractive" regimes to "inclusive" regimes is a big theme for Wade's new book.
In thinking about classical liberalism as evolutionary niche construction working through self-domestication, it might help to compare the argument of Helen Leach for the evolution of human self-domestication and the argument of Brian Hare and Richard Wrangham for bonobo self-domestication. Hare and Wrangham explain why bonobo psychology differs from chimpanzee psychology: because of relaxed feeding competition among bonobos, there was selection against male aggression and for social tolerance, because female coalitions forced males to be less aggressive and less dominant over the females, which created a cascade of effects leading to neotenous development through self-domestication. Classical liberalism might have created the cultural environment for human self-domestication so that human beings became more inclined to peaceful cooperation, and thus more like bonobos than chimpanzees.
Brian Hare, Victoria Wobber, Richard Wrangham, "The Self-Domestication Hypothesis: Evolution of Bonobo Psychology Is Due to Selection Against Aggression," Animal Behaviour 83 (March 2012): 573-85. Available online.
Evan Ratliff, "Taming the Wild," National Geographic, 219 (March 2011): 34-50. Available online.
Helen M. Leach, "Human Domestication Reconsidered," Current Anthropology 44 (2003): 349-68. Available online.
Lyudmila Trut, "Early Canid Domestication: The Farm-Fox Experiment," American Scientist, 87 (March-April 1999): 160-69. Available online.
Nicholas Wade, "Nice Rats, Nasty Rats: Maybe It's All in the Genes," New York Times, July 25, 2006. Available online.
Peter J. Wilson, The Domestication of the Human Species (Yale University Press, 1991).
There are some good videos on Belyaev's fox experiments.
Other posts on some of these points can be found here, here, here, here, here, here, here, here, here, and here.