Our ancestors were poor climbers
April 14th, 2009 - 1:06 pm ICT by ANIWashington, Apr 14 (ANI): A new study from Worcester State College in Massachusetts has revealed that our ancient human ancestors were poor climbers and they traded their ability of climbing trees for the power to walk on two legs.
According to anthropologist Jeremy DeSilva, early humans lacked the ankle structure that assists chimps- our closest living animal relatives - in climbing.
During the study, DeSilva videotaped wild chimpanzees in Uganda to study their bodies while climbing.
He measured the angle of dorsiflexion, or how far the ankle could rotate so that the toes point upward, and found that chimps can make much more extreme ankle rotations than modern humans.
He later analysed whether early hominins were more like modern humans or chimpanzees. He looked at the ankle bones in fossils of human ancestors at various times from 1.5 million to 4 million years ago.
DeSilva discovered that early humans during this span have dorsiflexion ranges similar to those of modern humans, and couldn’t have climbed trees in quite the same way as chimps do, if they climbed at all.
“Frankly, I thought I was going to find that early humans would be quite capable, but their ankle morphology was decidedly maladaptive for the kind of climbing I was seeing in chimps,” Live Science quoted DeSilva as saying.
“It kind of reinvented in my mind what they were doing and how they could have survived in an African savannah without the ability to go up in the trees,” he added.
As tree climbing was useful both for foraging food and for hiding from predators, the benefits of walking upright, say researchers, must have made humans give up their ankles more suited for climbing.
“I think by 3 [million] to 4 million years ago that tradeoff was occurring,” he said.
“Our ancestors were becoming very capable upright walkers, and it came at the expense to our ability to climb trees,” he added.
Other research suggests that early humans at this time had limb proportions similar to other mammal species that are particularly aggressive. Perhaps early humans used aggression to discourage predators from targeting them.
Moreover, walking on two feet not only enabled travelling long distances, but also escaping more quickly on the ground from predators.
The findings appear in journal Proceedings of the National Academy of Sciences. (ANI)
- Humans walked upright to carry scarce resources - Mar 25, 2012
- Big babies 'may have helped define the shape of modern human societies' - Jan 12, 2011
- 'Lucy' walked on two feet with human ancestors 3.2 mn-yrs ago - Feb 11, 2011
- Chimps likely to warn groups unaware of dangers - Dec 30, 2011
- Early humans more promiscuous than modern-day people - Nov 04, 2010
- Four new species discovered may shed light on human evolution - Apr 23, 2011
- High hormone levels drove cavemen to promiscuity - Nov 04, 2010
- Fossils show mysterious human species lived 30,000 years ago - Dec 23, 2010
- Discovery of "Ardi" named breakthrough of the year - Dec 18, 2009
- Early humans lived in Savannas, not forests - May 28, 2010
- Early humans may have been prey, not predators - Oct 13, 2010
- Fear of predators forced primates into social group - Nov 15, 2011
- Our earliest human ancestors may have walked upright 6 million years ago - Mar 21, 2008
- Humans switched from living in trees to on the ground 4.2mn yrs ago - Jan 29, 2011
- Big babies shape up the early human societies - Jan 11, 2011
Tags: african savannah, animal relatives, ankle bones, anthropologist, chimpanzees, chimps, desilva, dorsiflexion, early humans, hominins, human ancestors, limb proportions, live science, million years, poor climbers, tradeoff, tree climbing, two legs, upright walkers, worcester state college