Once again life imitates a Keats-and-Chapman joke

Back in 2006, Lieberman et al. examined the theory that the gluteus maximus muscle had evolved to its current size and shape in humans -- the very pinnacle of perfection -- to allow our primitive hominid ancestors to perform Groucho Marx imitations. The evidence was negative, however, including an absence of fossilised cigars, so like good scientists they abandoned that hypothesis and concluded that running is the activity most dependent on the buttocks, where they stabilise the forward lean of the torso. Walking, of course, is not particularly buttock-intensive.

This sounds like a re-invention of the old 'cursorial hunter' account of human evolution... that our ancestors in Africa occupied a Noble Hunter predatory guild where they out-ran their prey into exhaustion. In fact Lieberman subscribes to the less-flattering 'hyena competitor' account, that early hominids were scavengers who relied on out-running the vultures and jackals to reach the carcasses first.

You might think that the people to settle this question one way or the other are evolutionary psychologists. Adept as the evo-psych crowd are at explaining aspects of modern-day psychology in terms of evolutionary pressures faced by our ancestors, surely they could work backwards from contemporary psychology to rule out one account or the other. Yet they are unaccountably reluctant to make a concrete deduction that might be verified or falsified by developments in paleontology and by which their credibility might be judged. But I digress.

Lieberman's work has been in the news again this year, for there is always an audience for blog-posts about firm well-muscled backsides.
The take-home message is that human evolution has left no stern un-toned.