Perhaps no other activity is as peaceful as massage, with one human’s hands kneading and stroking another’s muscles.

Now, perhaps massage can be seen as another step in human evolution, with the release of a new study that indicates human hands evolved not only for the manual dexterity needed to use tools, play a violin or paint a work of art, but so men could make fists and fight.

Compared with apes, humans have shorter palms and fingers and longer, stronger, flexible thumbs–features that have been long thought to have evolved so our ancestors had the manual dexterity to make and use tools, according to a University of Utah press release.

“The role aggression has played in our evolution has not been adequately appreciated,” says University of Utah biology Professor David Carrier, senior author of the study, scheduled for publication Dec. 19 by the Journal of Experimental Biology.

“There are people who do not like this idea, but it is clear that compared with other mammals, great apes are a relatively aggressive group, with lots of fighting and violence, and that includes us,” Carrier says. “