In David Carrier’s lab, it looked like a horror movie.
Human arms, chopped off midway up the bicep, forearms dissected, fishing line strung up on each of the tendons so he could manipulate the fingers. The arms, affixed to pendulums, swung limp or as fists or as open palms at dumbbells.
The conclusion of his experiment: Human beings evolved to be a little more violent.
But David Carrier isn’t a Hannibal Lecter type. And this isn’t a rig set up for Halloween or, worse, a particularly weird and gruesome crime scene.
Carrier is a comparative biomechanist and professor at the University of Utah, testing his hypothesis that our hands evolved to fistfight. And after swinging a bunch of real, formerly live human hands in various poses and measuring their force, he came to precisely that conclusion: Our hands at first evolved to make a fist that could channel strength and withstand more force.
People with fists that could pack a punch survived and bred, he determined.
But now he’s warning against people drawing their own conclusions from his research. Just because we evolved to be slightly more violent thousands of years ago doesn’t mean it’s better or smarter—or even in our nature—to be violent now.
But let’s back up and about what you’re already thinking: Yes, our hands evolved so they could use and handle tools, just as you were taught. But they had to be better for fighting, too.
“There’s no question that our hands are specialized for manual dexterity,” Carrier told The Daily Beast. “[The] whole order of Primates specialized for using things with your hand. There was selection to make the thumb more opposable. If we shortened fingers in different ways, our dexterity would increase. That was always happening.
“But there’s a specific set of proportions of the different bones in the hand that allow for a clenched fist.”
Only two other kinds of primates have hands that are specialized for dexterity. But they can’t make a fist that is good enough for punching.
“It would have to be a real coincidence to have proportions that allow for the formation of a fist,” Carrier said.
That’s why he got a handful of undergrads from the University of Utah in a room with a bunch of cadaver arms.
“The issue was we had a very specific idea we needed to test. The proportions of our hand allow energy to be transferred from the index finger through the thumb to the wrist. That way, there’s less energy applied to the palm,” he said.
Carrier thought about using a mathematical model to prove it, but eventually he came to a conclusion: “We just realized the only way to do this was through a cadaver system.”
So he started making phone calls.
“At that point, I wasn’t sure that body donor programs would donate some specimens for a study like this. But it turns out that it didn’t faze any of the programs,” he said. “They’re providing all kinds of body parts for all kinds of studies. We just had to purchase the specimens.”
(We’d show you pictures, but Carrier wants to respect the donors who gracefully lent a hand.)
Then came the hard part: asking a bunch of college students if they wanted to remove tendons from some human forearms, then run fishing line up those same arms for an experiment.
Or so you would think.
“It was surprisingly easy. I think, in the beginning, it was a little bit shocking for them. But I think, maybe, they didn’t have a good sense for how unusual this was,” he said. “[Over time], they sort of took it as if this is a normal thing to be doing.”
With a helping, um, hand from his students, Carrier placed an arm on a pendulum—once as a fully clenched fist, once as “a fist not really clenched,” and once preparing for an open palm strike—and flung them hard at a padded dumbbell, watching over the accelerometer and transducers that were attached.
It’s now clear to Carrier: Selection favored those who could throw a better punch.
“We think, at that time, there was selection for improved dexterity and for conflict or a fight,” he said. “Not for one or the other.”
And that’s the most important point Carrier now wants to make: at that time, selection favored the fighter.
Since his research, for obvious reasons, attracted a mountain of press coverage, many have come to conclude that, even now, the more violent will be fitter to survive in the almost unimaginably lengthy process of evolution. Some, he says, are using it as a justification for our violent impulses.
That is simply wrong, he says.
“A lot of the criticism we’ve gotten is coming from a fear that evidence suggesting aggression was important justifies bad behavior or continued violence,” he said. “They’re saying, ‘Just because we selected by violence in the past, that’s who we truly are.’ But understanding is not justification. Understanding why sugar tastes sweet doesn’t mean we should all eat a junk food diet.”
Carrier says this kind of conclusion plays into an “attitude of fear.”
“If there is really a dark side to human nature, we should understand it. We should do everything we can to confront that impulse,” he said.
After all, when’s the last time you had a fistfight with somebody to prove, once and for all, that you could reproduce?
“Things that made sense tens of thousands of years ago don’t necessarily make sense in modern society,” he says.
“If there is something about our nature that leads us to responding with anger and fear and violence, we need to face it.”