Monday, December 11, 2006


Why altruism paid off for our ancestors

Humans may have evolved altruistic traits as a result of a cultural 'tax' we paid to each other early in our evolution, a new study suggests.

The research also changes what we knew about the genetic makeup of our hunter-gatherer ancestors.

The origin of human altruism has puzzled evolutionary biologists for many years (see Survival of the nicest).

In every society, humans make personal sacrifices for others with no expectation that it will be reciprocated. For example, we donate to charity, or care for the sick and disabled. This trait is extremely rare in the natural world, unless there is a family relationship or later reciprocation.

One theory to explain how human altruism evolved involves the way we interacted as groups early in our evolution. Towards the end of the Pleistocene period – about 12,000 years ago - humans foraged for food as hunter-gatherers. These groups competed against each other for survival.

Continued at "Why altruism paid off for our ancestors"

Based on the journal Science paper "Group Competition, Reproductive Leveling, and the Evolution of Human Altruism" by Samuel Bowles*

Science 8 December 2006:
Vol. 314. no. 5805, pp. 1569 - 1572
DOI: 10.1126/science.1134829


Humans behave altruistically in natural settings and experiments. A possible explanation - that groups with more altruists survive when groups compete - has long been judged untenable on empirical grounds for most species. But there have been no empirical tests of this explanation for humans. My empirical estimates show that genetic differences between early human groups are likely to have been great enough so that lethal intergroup competition could account for the evolution of altruism. Crucial to this process were distinctive human practices such as sharing food beyond the immediate family, monogamy, and other forms of reproductive leveling. These culturally transmitted practices presuppose advanced cognitive and linguistic capacities, possibly accounting for the distinctive forms of altruism found in our species.

*Info on Samuel Bowles:

My research focuses on two areas (much of it conducted jointly with Herbert Gintis). The first concerns the co-evolution of preferences, institutions and behavior, with emphasis on the modeling and empirical study of cultural evolution, the importance and evolution of non-self-regarding motives in explaining behavior, and applications of these studies to policy areas such as intellectual property rights, the economics of education and the politics of government redistributive programs. Included are agent-based modeling and other studies of what I term "property rights revolutions." Much of this research is carried out as part of the MacArthur Research Network on Preferences and in conjunction with the Behavioral Sciences Program at the Santa Fe Institute.

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