Study Sheds Light on Evolution of Tree-Dwelling Humans

Lucy, a member of a prehistoric primate species, likely lived both in trees and on the ground.

WEDNESDAY, Jan. 2 (HealthDay News) -- In human evolution, walking on two legs is a big deal. It marks the debut of humans as animals who live on the ground instead of in trees -- and researchers now have evidence of when this change took place.

A new study suggests that "Lucy," a member of a prehistoric primate species that appeared about 3.5 million years ago in Africa, lived in both worlds. Lucy, the researchers believe, could both climb trees and walk on the ground.

Until now, the ankles and feet of the Australopithecus afarensis indicated that the species wasn't able to climb trees easily, the study authors noted in the new report. But the researchers, led by Dartmouth College associate professor of anthropology Nathaniel Dominy, looked at modern humans in Africa and the Philippines and found that they could effectively climb trees.

This dual ability has to do with the capacity of some of the people studied to bend their feet upward toward the shin, beyond the range of motion normally seen in modern humans, helping them to climb trees, the study authors explained.

The findings suggested that hunter-gatherers like Lucy could both climb trees and walk.

The study is published in the current issue of the journal Proceedings of the National Academy of Sciences.

More information

For more on Lucy, visit pbs.org.