Study: Human Hand Evolved So Fist Could Club Enemies

Posted December 19th, 2012 at 11:09 pm (UTC-4)

A clenched human fist ((Photo: Ralpharama via Wikimedia Commons)

A clenched human fist (Photo: Ralpharama via Wikimedia Commons)

The human hand is a sophisticated work of art and science. Refined through centuries of evolution, hands enable us to perform unique functions which help us to not only survive but also to thrive as a species.

New research suggests the evolution of the modern human hand may be due to a very basic need: for use as a weapon.

In a study published in The Journal of Experimental Biology,  University of Utah scientists theorize human hands evolved their unique square palms and long thumb in order to stabilize the fist, providing a built-in compact club early humans could use in combat.

An impassioned conversation with a colleague inspired David Carrier to pursue research on the matter.

In the course of their conversation, Frank Fish, an expert in biomechanics, formed a fist and said, “I can hit you in the face with this, but that is not what it evolved for.”

Fish’s proclamation made Carrier stop and think. While the human hand evolved to allow great dexterity, according to Carrier, a chimpanzee can also manipulate its hands in a way that would give it greater manual dexterity, but they still may not necessarily be able to form their hands like humans do.

Modern chimpanzees, according to Carrier, have long palms and fingers with a short thumb, while the human palm and fingers are much shorter and the thumb longer and stronger.

Three views of a clenched human fist show how we buttress the fist to reduce the chance of hand injury when punching. (Photo: Denise Morgan for the University of Utah)

Three views of a clenched human fist show how we buttress the fist to reduce the chance of hand injury when punching. (Photo: Denise Morgan for the University of Utah)

This difference brought on by evolution, allows us to clench our hand into a fist whenever we fold our thumb across the fingertips.  A chimpanzee’s fingers, on the other hand, forms the shape of what he describes as an open doughnut shape when curled.

Carrier said that he wondered if the tightly-packed human fist provides some internal support to our fingers in order to protect them from being damaged during an altercation and if it also provides humans with the ability to deliver a more powerful blow against their opponents, as compared to the slap of an open hand.

Carrier and Morgan decided to find out whether hands are more effective when balled into a fist or used as an open-handed slap.

“Fortunately, Michael had a lot of experience with martial arts and he knew people who were willing to serve as subjects,” said Carrier.

First, the test subjects were asked to smack a punching bag with their hands formed into a wide variety shapes; from the open-handed slap to the tightly-clenched fist, using various styles to deliver the blows, such as over the arm, sideways and head on. As each of the fighters walloped their punching bag foe, the researchers would measure the force of each impact.

But after looking at the results of that experiment, the researchers were surprised to see the punch did not deliver more force per blow.

“In terms of the peak forces or the impulse, it did not matter whether the subjects were hitting with a clenched fist or open palm,” said Carrier.

With fists only a human hand can form, a fighter delivers a devestating punch to her opponent. (Photo: Courtney "Coco" Mault/Wikipedia Commons via Flickr)

Fists formed only by a human hand can be used as a weapon without causing injury to the person delivering the punch. (Photo: Courtney “Coco” Mault/Wikipedia Commons via Flickr)

Morgan and Carrier then wanted to find out whether supporting the hand, by curling the fingers and thumb, stiffens the structure of the hand. Asking their test subjects to form their hands into various fist shapes, the researchers measured the rigidity of the first knuckle joint of their subject’s index finger, first with the support of the thumb over the finger and then without the support of the thumb. They found the knuckle joint was four times more rigid when supported by the thumb.

Next, the researchers measured the amount of force that the fighters could deliver through the fist surface of their index and middle fingers. Again, they found that by using the thumb in forming a fist, the test subjects doubled the delivered force by transmitting it to the wrist through the palm bones of the thumb and the index finger.

The results of their experiments led Carrier and Morgan to conclude  the square-shaped palms of today’s humans are perfectly proportioned to stiffen into a fist to be used as a weapon that delivers powerful punches without injuring ourselves.

Rick Pantaleo
Rick Pantaleo maintains the Science World blog and writes stories for VOA’s web and radio on a variety of science, technology and health topics. He also occasionally appears on various VOA programs to talk about the latest scientific news. Rick joined VOA in 1992 after a 20 year career in commercial broadcasting.

9 responses to “Study: Human Hand Evolved So Fist Could Club Enemies”

  1. I am not sold on this theory yet. After all, for anyone who follows boxing you know that the boxing glove was not invented to protect the person getting hit. Rather, it was invented for the sport to protect the hands of the person throwing a punch. Punching with a closed fist is actually a very ineffective technique. The hand is very fragile and a punch easily can break a person’s hand. If this is an evolutionary trait, it doesn’t make sense.

    • says:

      This study does look like a real discovery. We can speak now of “Homo Fisty” or “Homo Clubbed” (no sarcasm intended). The defensive use of the fist could not but play a significant role in the evolution of the human hand and the fingers:thumb ratio along with its peaceful uses. Maybe, even a more significant role over its peaceful uses, which is the BACKBONE of Mr. Carrier’s discovery. Because our fist is really a compact, portable weapon that is always about us from time immemorial. By the way, no well-trained fist could ever be broken against a forehead or even a kneecap. The Wrestling Roots should know that. The plethora of the protective tools like boxing or grappling gloves are invented to protect the opponent, not the fist (OK, in the AIDS era, gloves are good for protecting the thin flesh layer on the knucklebones either). Then, It is known that a good punch can flatten and cool down a raging male chimpanzee (Do not try it at home unless you are a good puncher), to say nothing of a dog or a smaller culprit :). Again, no great apes use clenched fists to punch, even gorillas, who do have keratin knuckle pads, but due to walking on fists, not punching.
      BIG HAND! Awe and Respect to the author of the study!

  2. chris says:

    Im far from sold…this sounds like NRA nonsense pumped up now to defend the 2nd amendment. So I soon expect to hear that our index finger was evolutionary selected for so we could have gods gifted right to pull the trigger. “its in our genes man to have guns..why else would we have trigger fingers” (scarcastic)

    How about the whole hand structure was evolutionary selected for many other reason because of the many advantages it offered in aquiring food and using tools..

    read this again and ask if it makes any sense. “man developed the fist so he could punch the living daylights out of people and animals.. so he could get laid.. and pass off his genes”
    There is more to evoluton of the human hand/body than this. I hope not too much taxpayer grant money was wasted on this study.. The publishers should be shamed for printing such monkey science.

    • One tired customer says:

      Seriously? NRA financed study? You really bore me with your leftist screeching… Of course human hand is part of the duo that made us who we are (right or wrong). The brain invents the tools and the opposable thumb makes us able to make / use them. Yes, fist can be and have certainly been used for punching, but it is far from a very effective punching tool — it is actually quite fragile when it comes to contact with hard surfaces like forehead. Hence all the protective tactical gloves, knuckledusters, and a plethora of other “fist related” tools we’ve invented to protect the hand and/or make it a better weapon.

  3. no_one says:

    Any dumb ape can punch. Would selection for the human hand and thumb ratio greater to grip and wield tools, including weapons? Every punk on the street knows you don’t punch bare handed if you can carry a roll of quarters (or swing a stick or sharpened flint). When the other great apes evolve the eyes and brains to make and wield tools effectively, I would expect similar hand ratios to emerge.

  4. Alma Rose says:

    Just saying, I think there’s at least one ape who can punch just fine:

  5. Laura says:

    Ummm – this is a great example of the post hoc fallacy (‘after this, therefore because of this’). There’s a concept known as an “affordance” and another concept called an “exaptation” that can easily apply here. You can think of an affordance as a side benefit of an artifact – it’s a use or an application that isn’t the primary purpose of the artifact, but which the artifact supports regardless. Exaptation occurs when an evolved trait, such as the bone structure of a human hand, gains a purpose that’s not directly related to the evolutionary pressures that shaped the development of that feature.

    This “finding” is very questionable science. Sigh.

    • says:

      Then, military application of nuclear power is another great example of post hoc fallacy and “affordance” (sarcasm). I think no use chanting mantras like “We are goodies, goodies, gooodieees”. We are no goodies as we are, just trying to be better, that’s the given. Just wallop thy punchbag if thy fist itches, but hit not thy brother’s eye.

  6. Jason says:

    “Far from the truth lay the antique assumption that man had fathered the weapon. The weapon, instead, had fathered man.”
    Robert Ardrey