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Standing up to fight, and human uniqueness
May 19, 2011Posted by on
A new paper published in PLoS ONE by David Carrier tests the hypothesis that bipedalism in humans evolved because it helps them to fight better. The first fatal flaw lies in the first sentence:
Many quadrupedal animals stand on their hindlimbs to fight.
How then, does this explain human uniqueness?
“… it is illogical to invoke the behaviour of living apes to explain the origins of something that they themselves have not developed…”
and I think it would be great if we could ask ourselves why all of these bipedal aggression postures haven’t resulted in bipedal anteaters, felids, or canids, but were so important in human evolution. My dog does a cute little thing where she stands up on her hind legs to pounce a squeaky toy. Perhaps if I hadn’t had her spayed, her descendants would have been bipedal? (She also stands up to get food from low-hanging branches….er… coffee tables.)
A second flaw lies in their methodologies, in which they had humans stand bipedally to strike a force transducer, and then had them get down on their hands and knees and do the same thing. What ancestral state does this posture approximate? Forget bent-knee, bent-hip- let’s go with knee-crawling! The authors themselves admit,
The fact that humans are habitual bipeds reduces the relevance of humans as a model organism for this study.
but add that using chimpanzees or bonobos would increase the “relevancy” of this particular experiment. I don’t think it would. Chimpanzees and bonobos don’t represent an ancestral hominid, either. You’d want to get a sample that included a bunch of different species- monkeys, anteaters, felids (why not?). But I still don’t know that a protocol like that would support the hypothesis that humans evolved to be bipedal because that particular aggressive posture was important to their ability to secure a mate.
Carrier, D. (2011). The Advantage of Standing Up to Fight and the Evolution of Habitual Bipedalism in Hominins PLoS ONE, 6 (5) DOI: 10.1371/journal.pone.0019630