If heel-striking is so unnatural, why do apes do it?
In the wake of Dan Lieberman’s foray into the barefoot running debate, there’s an interesting counterpoint in the newest Journal of Experimental Biology from David Carrier of the University of Utah — the man who anticipated Lieberman’s 2004 “endurance running” evolutionary hypothesis by 20 years.
In a nutshell, Carrier’s paper points out that heel-striking — a.k.a. “the devil,” as far as Lieberman is concerned — actually has advantages in some contexts. As the Utah press release puts it:
Humans, other great apes and bears are among the few animals that step first on the heel when walking, and then roll onto the ball of the foot and toes. Now, a University of Utah study shows the advantage: Compared with heel-first walking, it takes 53 percent more energy to walk on the balls of your feet, and 83 percent more energy to walk on your toes. […]
Economical walking would have helped early human hunter-gatherers find food, he says. Yet, because other great apes also are heel-first walkers, it means the trait evolved before our common ancestors descended from the trees, [Carrier says].
The main point of the paper is that it’s curious that our foot anatomy is adapted to heel-strike while walking (i.e. we have a big, prominent heel), unlike most other mammals. But it’s a trait we share with all the other great apes, so it’s not something that was only created by the advent of thick-heeled modern shoes. As both Carrier and Lieberman have argued, many of our anatomical features seem to have evolved precisely to favour endurance running — but our heels, in contrast, seem better suited walking. This isn’t that surprising, the authors argue, given that both running and walking were likely essential to early hunter-gatherers.
Ultimately, none of this conflicts with the arguments put forth by Lieberman. Even if it’s natural to heel-strike while walking, the evidence suggests that early humans didn’t heel-strike while running. (Though the new study confirms earlier findings that there’s no difference in efficiency between heel-foot and fore-foot striking for running.) But as the barefoot running debate heats up, it’s interesting to note that heel striking has an evolutionary origin.