Human hands might have evolved to a certain shape over time for an important survival skill: punching. That's according to a recent study conducted by researchers at the University of Utah.
The research team says their findings support the controversial idea that the proportion of the human hand evolved not only for fine manipulation but also to make a fist that can protect the person from a potential injury.
In the study, the researchers used different positions of the arm to punch a dumbbell. The different positions included a slap with an open palm, a clenched fist and a relaxed fist. The team found that a clenched fist was the best way for protection without getting hurt.
David Carrier, a comparative biomechanist, and his colleagues made use of nine human male cadaver arms purchased from private supply companies and the university's body donor program. The cadaver arms were kept frozen until they were tested during the study.
After several rounds of slaps and punches using the cadaver arms, the research team found that humans with a buttressed fist can strike with 55 percent more force as compared to humans with an unbuttressed fist.
Based on the study results, the researchers suggest that human hands might have evolved to improve both manual dexterity and to act as a club during fights. However, they say that these might not be the only reasons behind the modern-day shape of the human hand.
The study findings have met with mixed reviews from experts: While some agree with the findings, others say that the conclusion from the bone-strain data is problematic.
"I think a lot of the criticism we get comes from a fear that any evidence of aggressive behavior having been important in our evolution somehow provides a kind of justification for bad behavior," said Carrier in an interview with Live Science. "Rather than justifying aggression, an improved understanding of who we are, of human nature, should help us prevent violence of all kinds in the future."
The complete details of the study were published in the Oct. 21 issue of the Journal of Experimental Biology.