Despite the fact that Gibbons are the most speciose of the apes (with at least nine species of gibbons and siamangs) with many interesting characteristics (they are the most anatomically primitive of the apes and retain many “monkey” like features, at the same time they are the most specialized of the living hominoids) one hears very little about them.
So I was happy to hear about the recent article published in the Journal of Experimental Biology that looked at terrestrial locomotion in Hylobates lar. Nature also has a story on the subject. Researchers created a walkway in an enclosure containing four gibbons and filmed the gibbons as they walked through it. (Videos can be found here and here.)
From the Nature News article:
Whereas humans and horses have two very distinct gaits, walking and running, gibbons only rarely engage in a way of locomotion that resembles our walk, where the legs are swung like pendulums. Instead, at all speeds, they propel themselves in a springy, bouncy fashion closer to our run.
But unlike humans, they do not use their Achilles tendons as the main spring. Vereecke hypothesizes that they might use their quadriceps muscles instead.
Also unlike a human, they never have both feet off the ground at the same time. Vereecke suggests that this ‘aerial phase’ (think of this lovely expression on your next jog) should not be a requirement to call something a run.
The results are not without controversy, however:
Liza Shapiro, a primate locomotion specialist at the University of Texas, Austin, is a bit less impressed with the gibbon bouncy gait. She points out that the study also shows that the gibbons’ centre of mass tends to roil about during this funny walk. “I get the impression that maybe their bipedalism isn’t very energy-efficient at all,” she says.
Which just goes to show that more research is needed before the question can be settled…
Filed under: Primates