Chimp Hands More Evolved Than in Humans, Study Finds

Chimp hands have evolved and become more sophisticated than human hands in the time since both primates diverged from a common ancestor about seven million years ago, theorizes a new study.

After examining the fossils of chimps and humans, and using statistical methods to determine the course of hand evolution, researchers in the study published Tuesday in the science journal Nature Communications determined that the common ancestor of both, along with an earlier ape ancestor, had hands similar to what humans have today, according to Science magazine.



"Thus, the human hand retains these more 'primitive' proportions, whereas the elongated fingers and shorter thumbs of chimps, as well as orangutans, represent a more specialized and 'derived' form ideal for life in the trees …," wrote Michael Balter of Science magazine.

Researchers said it was their "neurological" changes that led humans to create tools. Brain development also allowed humans better hand coordination and to plan ahead.

The Nature Communications study confronts the previous assumption that the last common ancestor of humans and chimps would have had hands like modern day chimpanzee, according to Tech Times

"Any evolutionary model of human hand evolution assuming a chimpanzee-like ancestor will likely be flawed from the beginning," said study leader Sergio Almecija of the Center for the Advanced Study of Human Paleobiology at George Washington University.

The study suggested that when hominids began making flaked stone tools about 3.3 million years ago, their hands looked a lot like human hands today in terms of overall shape and proportion.

Balter wrote in Science that the Nature Communications' study, though, has not found a lot of backing from other researchers who believe the common ancestor of human and chimps looked more like chimpanzees.

"(The team) build(s) an evolutionary scenario based on one data point, bony proportions of hands, with the underlying assumption that they tell a story," Adrienne Zihlman, a primatologist at the University of California, Santa Cruz told Science.

"This paper serves as a poster child for what is wrong with a lot of work in paleoanthropology," said Zihlman.

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