Human Opposable Thumbs Evolved For Punching, Study

A new study by a biologist at the University of Utah  says that opposable thumbs have evolved due to the need to "throw punches".

"The idea that aggressive behavior played a role in the evolution of the human hand is controversial," said David Carrier, senior author of the study, according to a press release. "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," according to HNGN.

For the experiment, scientists used male cadaver arms and tied tension lines to the tendons. These were used to adjust arms and hands in a way that the researchers wanted, and later the arms were used to "throw punches and slaps at a dumbbell designed to detect force." Researchers assessed the power of impact.

"Each one of these hands took about a week of work," said Carrier. "First we had to dissect it to expose the muscles, apply one or more strain gauges, and then attach the lines to all the tendons so you can control the position of the wrist, thumb and fingers to create a buttressed fist, unbuttressed fist or open-palm posture. Everything had to be lined up just right - all the joints, tension in muscles, the orientation of bones."

Another interesting fact they believed in is that human faces evolved to "withstand punches", although recent faces have now got more sensitive due to less reliance on "brute force violence".

However, members of the evolutionary community refute this team's claim due to lack of strong enough evidence to prove it.

The study was published in the Journal of Experimental Biology.