Humans often think of themselves as the planet's superior species, but new researchers suggest our hands may be more primitive than chimp's.
Human hand proportions have barely changed from what was seen in the last common ancestor (LCA) of chimpanzees and humans, Stony Brook University reported. These findings suggest the structure of the modern human hand is essentially primitive, and is not the result of selective pressure from stone tool making.
Humans have a long thumb in relation to the other fingers, which has often been cited as one of the factors that helped us rule the Earth. There have been competing theories on how and why these unique hands developed.
To make their findings, a team of researchers of modern humans, living and fossils apes, as well as human ancestors including Ardipithecus ramidus and Australopithecus sediba.
"The results show the more recent, convergent evolution of finger elongation in chimpanzees and orangutans and comparatively little change between humans, human ancestors and gorillas," the researchers said.
The findings support the hypothesis that the long thumb to fingers ratio of the human hand developed at the same time as other highly dexterous anthropoids.
The findings also dispute the idea that a chimp-like hand was the "starting point" of the LCA's physique. The researchers believe the recent study will be met with outcries from scientists who believe the LCA was more chimp-like.
"[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 AAAS. Zihlman believes the hands alone offers only a very limited glimpse of the common ancestor. "This paper serves as a poster child for what is wrong with a lot of work in paleoanthropology."
The findings were published in a recent edition of the journal Nature Communications.
