What's new — Research published Wednesday in the journal Science Advances suggests the last common ancestor of hominids — a category of great apes that includes chimpanzees, gorillas, orangutans, and humans — climbed and swung in trees.

"Our findings support the view that humans and chimpanzees evolved from an ancestor that had similarities to modern apes in their locomotor adaptation," lead author Thomas C.

First, researchers analyzed the ancient hand bones of Ardipithecus ramidus, which believers of the disputed hypothesis use to support their idea regarding a quadrupedal last common ancestor.

The initial interpretation of this hand suggested the last common ancestors of humans and chimpanzees used a form of locomotion called "above-branch clambering," Prang explains.

"The hand of Ardipithecus suggests that the last common ancestor of humans and chimpanzees was adapted to climbing tree trunks and suspending the body beneath branches," Prang says.

"We show a major evolutionary jump between the hand of Ardipithecus and all later hominins that happens to coincide with the loss of tree climbing adaptations in the foot and the earliest known stone tools and stone tool-cut-marked animal fossils," Prang says.

"Our study provides some support for the hypothesis that human hands and feet 'co-evolved,' which previous studies have suggested on the basis of comparisons of patterns of hand/foot trait relationships, and evolutionary simulations, among humans and chimpanzees," Prang says.

"In this context, this new study identifies suspensory adaptations in the 4.4 million-year-old hand remains of Ardipithecus ramidus, suggesting that human hand morphology may have emerged from an evolutionary shift between Ardipithecus and Australopithecus," he says

"If it is true that humans and chimpanzees evolved from an African ape-like ancestor, it implies that each African ape lineage evolved at different rates," Prang says