Study supports the theory that human hands were evolved not only for manual dexterity but for fistfights as well
A new study suggests that unique human hand shape has developed to punch someone.
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It has been long debated what caused our hand to evolve current shape. Mostly believed, it developed over the years from our ancestors to perform variant tasks and to use different tools. But according to new study, hand evolved not only for manual dexterity but also for fistfights. Clenched fists make it safer to punch someone without getting hurt.
To support the theory, biologists from University of Utah used a living person’s cadaver arm to punch and slap bedded dumbbells in different positions.
"The idea that aggressive behavior played a role in the evolution of the human hand is controversial,” said David Carrier, a biology professor and lead author of the study. “Many skeptics suggest that the human fist is simply a coincidence of natural selection for improved manual dexterity. That may be true, but if it is a coincidence, it is unfortunate."
“As an alternative, we suggest that the hand proportions that allow the formation of a fist may tell us something important about our evolutionary history and who we are as a species. If our anatomy is adapted for fighting, we need to be aware we always may be haunted by basic emotions and reflexive behaviors that often don't make sense -- and are very dangerous -- in the modern world."
Humans have shorter palms and finger but long, strong, flexible thumbs, which is different from any other ape. To collect more evidence, Carrier and his colleagues examined nine male cadaver arms purchased from University’s body donor program and from a private supply company.
“We tested the hypothesis that a clenched fist protects the metacarpal (palm or hand) bones from injury (and fracture) by reducing the level of strain during striking.” Author wrote in study.
The cadaver arms were placed in a pendulum like apparatus, so they can swing forward to punch a padded, force-detecting dumpbell. Then, bone deformation, stretching and compression were measured.
“Our results suggest that humans can safely strike with 55 percent more force with a fully buttressed fist than with an unbuttressed fist, and with twofold more force with a buttressed fist than with an open hand slap.”
Carrier’s ideas about human hand are controversial and many other researchers seem unconvinced by these results. They are putting forward new questions and angles like if human hands are evolved to fight then the primary target – the face – should have coevolved protective features but it doesn’t seem to happened. For instance, nose hurts too badly when someone punches your face.
Carrier is not bothered much about these criticisms. In fact, he thinks naysayers are scared from the results.
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“There’s a fear, and I don’t think it’s necessarily valid, but there’s a real fear that evidence suggesting we’re anatomically built for fighting could be used to justify bad behavior," said Carrier. "What I would argue is that if our goal is to reduce violence in the future, we need to understand what this dark side of human nature is all about."