Human fist evolved to punch

Are human hands built for punching? A new study of cadaver arms suggests this may be the case.

By using the arms to hit a dumbbell three different ways, scientists determined that a clenched fist makes it much safer to serve someone a knuckle sandwich.

The findings, published this week in the Journal of Experimental Biology, bolster a controversial theory that ties human physiology to a violent past.

Compared with primates such as chimpanzees, humans have developed a very different hand structure that features a shorter palm, shorter fingers and a relatively longer thumb. The
conventional wisdom holds that our hands evolved for more dexterity, allowing our ancestors to wield and manipulate tools.

“There’s every reason to believe that,” said David Carrier, a physiologist at the University of Utah.

However, Carrier and his colleagues have put forth another, perhaps complementary, idea. They posit that as the human hand was becoming more delicate, it may have evolved into
just the right shape to fit into a fist — all the better for punching opponents without accidentally breaking one’s bones.

“Our results suggest that humans can safely strike with 55 per cent more force with a fully buttressed fist than with an unbuttressed fist,” Carrier and his colleagues wrote.

The tight fist also allowed for twice as much force as an open-handed slap, they added. As our hands grew more dexterous and delicate, the fist shape allowed men to use it as a
weapon, presumably to compete for access to potential mates. That behavior is seen in many other primates, Carrier said.

www.latimes.com