Robust Skeleton Suggests Human Ancestor Was Champion Climber and Walker

An analysis of a partial skeleton dating back some 1.34 million years suggests at least one ancient hominin retained the ability to climb millions of years after our ancestors are believed to have taken to the ground. 

Published in the journal PLOS ONE, the study points to the newly discovered fossils as clear evidence the human ancestor Paranthropus boisei was both an accomplished bipedal as well as tree-climber.

"This is something we didn't expect," Charles Musiba, an associate professor of anthropology at the University of Colorado Denver, told Nature World News about the animal's multi-tasking abilities.

Previous estimates place our ancestor's descent from the trees to land some 4 million years ago. Surprisingly, the new fossils show the P. boisei retained the hand and muscle structure that would have made swinging from tree to tree only natural, in addition to the frame needed for walking. 

"They had the full range of joints that would have allowed them to reach up and pull themselves up without a problem, which is something humans today can't do without training," Musabi explained, adding that the animals were also "very, very good bipeds."

The anthropologist Mary Leakey uncovered the first P. boisei skull in 1959 in Tanzania, revealing to the world the early hominin's massive jaws and cranium it quickly became known for.

The species is believed to have inhabited East Africa between roughly 2.3 million to 1.2 million years ago, though much remained a mystery about the early ancestor. Without more fossil evidence to go off of, researchers assumed it likely resembled an even more ancient species of the genus Australopithecus, from which it probably evolved.

"We knew about the kind of food it ate - it was omnivorous, leaning more toward plant material - but now we know more: how it walked around and now we know it was a tree climber," Musabi said.

The bones unearthed at the Olduvai Gorge World Heritage fossil site included nine teeth, a distal humerus fragment, a femur shaft, a proximal radius with much of its shaft and a tibia shaft fragment. The researchers identified the partial skeleton as belonging to an adult male that likely stood between 3.5-4.5 feet tall.

"It's unprecedented to find how strong this individual was," Musabi said, noting that the "stronger you are the more adaptive you are."

Going forward the researcher says his team plans to use the fossil record to develop a 3-D simulation recreating P. boisei's movements in even greater detail.