Darwin's inner voice -- Living the virtuous life -- Of altruism and free riders -- Knowing our immediate predecessors -- Resurrecting some venerable ancestors -- A natural Garden of Eden -- The positive side of social selection -- Learning morals across the generations -- Work of the moral majority -- Pleistocene ups, downs, and crashes -- Testing the selection-by-reputation hypothesis -- The evolution of morals -- Epilogue: humanity's moral future.

Michael Tomasello’s account of moral evolution includes both a synthesis of extensive experimental work done on humans and chimpanzees on their potential for perspective-taking and helpful, altruistic generosity and a major emphasis on “collective intentionality” as an important component of morality in humans. Both will be very useful to the evolutionary study of this subject. However, his disavowal of collective intentions on the parts of chimpanzees would appear to be empirically incorrect, owing to reliance on experimental captive research focused only (...) on dyadic interactions. Here, evidence to the contrary is provided from studies of wild chimpanzees as they naturally cooperate in sizable groups. Collective intentions are inferable when they go on patrol, when they mob predators, when they go hunting, and when large coalitions gang-attack disliked members of the same community. This last behavior has particularly significant pre-adaptive implications for the evolution of moralistic social control, and it suggests that moral evolution has deep roots, going back to the Last Common Ancestor of humans, bonobos, and chimpanzees. (shrink)

Proponents of the standard evolutionary biology paradigm explain human “altruism” in terms of either nepotism or strict reciprocity. On that basis our underlying nature is reduced to a function of inclusive fitness: human nature has to be totally selfish or nepotistic. Proposed here are three possible paths to giving costly aid to nonrelatives, paths that are controversial because they involve assumed pleiotropic effects or group selection. One path is pleiotropic subsidies that help to extend nepotistic helping behavior from close family (...) to nonrelatives. Another is “warfare”—if and only if warfare recurred in the Paleolithic. The third and most plausible hypothesis is based on the morally based egalitarian syndrome of prehistoric hunter-gatherers, which reduced phenotypic variation at the within-group level, increased it at the between-group level, and drastically curtailed the advantages of free riders. In an analysis consistent with the fundamental tenets of evolutionary biology, these three paths are evaluated as explanations for the evolutionary development of a rather complicated human social nature. (shrink)

Hunter-gatherer punishment involves costs and benefits to individuals and groups, but the costs do not necessarily fit with the assumptions made in models that consider punishment to be altruistic – which brings in the free-rider problem and the problem of second-order free-riders. In this commentary, I present foragers' capital punishment patterns ethnographically, in the interest of establishing whether such punishment is likely to be costly; and I suggest that in many cases abstentions from punishment that might be taken as defections (...) by free-riders are actually caused by social-structural considerations rather than being an effect of free-rider genes. This presentation of data supplements the ethnographic analysis provided by Guala. (shrink)

Using criteria of relative plausibility, it is possible to make a case for significant group selection over the 100,000 years that Anatomically Modern Humans have been both moral and egalitarian. Our nomadic forebears surely lived in egalitarian communities that levelled social differences and moralistically curbed free-riding behaviour, and this egalitarian syndrome would have had profound effects on levels of selection. First, it reduced phenotypic variation at the within-group level. Second, it increased phenotypic variation at the between-group level. Third, and crucially, (...) moral sanctioning also permitted groups to sharply curtail free-riding tendencies at the level of phenotype. The result was group selection strong enough to support altruistic genes, and a human nature that was set up for social ambivalence: that nature was mainly selfish and strongly nepotistic, but it was at least modestly and socially significantly altruistic. The effects on human social and moral life were pervasive, both in hunting bands and in more recent manifestations of human society. (shrink)