LONDON: Scientists use arms taken from corpses to test why humans developed the ability to punch well
The human hand evolved to be effective in fistfights, scientists have found, after they tested their theory using the arms of dead people.
Humans have shorter palms and fingers and longer, stronger, more flexible thumbs than apes, which some biologists believe evolved not just for manual dexterity but to form a punching fist.
Now researchers from the University of Utah have tested that hypothesis by using eight arms from male corpses to perform hundreds of punches and slaps.
The idea that aggressive behaviour played a role in the evolution of the human hand is controversial,” said Prof David Carrier, senior author of the study.
“Many sceptics 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.”
The clenched fist is believed to protect the metacarpal bones of the palm by transferring part of the impact through the thumb to the wrist, allowing the hand to be used as a club.
“Metacarpals are bones in the hand that break most often – not finger bones, but bones of the palm,” Prof Carrier said.
Researchers placed the arms in a pendulum-like piece of equipment to allow them to swing towards and punch a padded, force-detected dumbbell.
