Forager Anthropology
(This is the second post in a short sequence discussing evidence and arguments presented by Christopher Ryan and Cacilda Jethá's Sex at Dawn, inspired by the spirit of Kaj_Sotala's recent discussion of What Intelligence Tests Miss. It covers Part II: Lust in Paradise and Part III: The Way We Weren't.)
Forager anthropology is a discipline that is easy to abuse. It relies on unreliable first-hand observations of easily misunderstood cultures that are frequently influenced by the presence of modern observers. These cultures are often exterminated or assimilated within decades of their discovery, making it difficult to confirm controversial claims and discoveries. But modern-day foraging societies are the most direct source of evidence we have about our pre-agricultural ancestors; in many ways, they are agriculture's control group, living in conditions substantially similar to the ones under which our species evolved. The standard narrative of human sexual evolution ignores or manipulates the findings of forager anthropology to support its claims, and this is no doubt responsible for much of its confused support.
Steven Pinker is one of the most prominent and well-respected advocates of the standard narrative, both on Less Wrong and elsewhere. Eliezer has referenced him as an authority on evolutionary psychology. One commenter on the first post in this series claimed that Pinker is "the only mainstream academic I'm aware of who visibly demonstrates the full suite of traditional rationalist virtues in essentially all of his writing." Another cited Pinker's claim that 20-60% of hunter-gatherer males were victims of lethal human violence ("murdered") as justification for a Malthusian view of human nature.
That 20-60% number comes from a claim about war casualties in a 2007 TED talk Pinker gave on "the myth of violence", for which he drew upon several important findings in forager anthropology. (The talk is based on an argument presented in the third chapter of The Blank Slate; there is a text version of the talk available, but it omits the material on forager anthropology that Ryan and Jethá critique.)
At 2:45 in the video Pinker displays a slide which reads
Until 10,000 years ago, humans lived as hunter-gatherers, without permanent settlements or government.
He also points out that modern hunter-gatherers are our best evidence for drawing conclusions about those prehistoric hunter-gatherers; in both these statements he is in accordance with nearly universal historical, anthropological, and archaeological opinion. Pinker's next slide is a chart from The Blank Slate, originally based on the research of Lawrence Keeley. Sort of. It is labeled as "the percentage of male deaths due to warfare," with bars for eight hunter-gatherer societies that range from approximately 15-60%. The problem is that of these eight cultures, zero are migratory hunter-gatherers.



