Standing up to fight: Does it explain why we walk upright, why women like tall men?

May 18, 2011
These two photo sequences depict a key part of a University of Utah experiment that showed why there is a fighting advantage to walking on two legs and being tall -- something that may help explain why ape-like human ancestors started walking upright and why women today tend to prefer tall men. In the top three photos, a participant in the study kneels with four limbs on the ground and then raises one arm to strike downward on a padded block equipped with sensors to measure the force of the blow. The bottom three photos show the same experiment, but with the blow delivered from an upright position. The study found that blows delivered downward from a two-legged posture are more powerful than downward blows from an all-fours posture, or than any blows delivered upward, from the front or sideways. Photo credit: David Carrier, University of Utah

(PhysOrg.com) -- A University of Utah study shows that men hit harder when they stand on two legs than when they are on all fours, and when hitting downward rather than upward, giving tall, upright males a fighting advantage.

This may help explain why our ape-like began walking upright and why women tend to prefer tall men.

"The results of this study are consistent with the that our ancestors adopted bipedal posture so that males would be better at beating and killing each other when competing for females," says David Carrier, a biology professor who conducted the study. "Standing up on their hind legs allowed our ancestors to fight with the strength of their forelimbs, making punching much more dangerous."

"It also provides a functional explanation for why women find tall men attractive," Carrier adds. "Early in , an enhanced capacity to strike downward on an opponent may have given tall males a greater capacity to compete for mates and to defend their resources and offspring. If this were true, females who chose to mate with tall males would have had greater fitness for survival."

Carrier's new study is being published Wednesday, May 18 in the online Public Library of Science journal .

The idea is not new that fighting and violence played a role in making human ancestors shift from walking on all fours to walking on two legs. But Carrier's new study physically demonstrates the advantage of fighting from an upright, two-legged posture.

Carrier measured the force of punches by male boxers and martial arts practitioners as they hit in four different directions: forward, sideways, down and up.

A punching bag fitted with a sensor measured the force of forward and sideways punches. For strikes downward and upward, the men struck a heavy padded block on the end of a lever that swung up and down because it was suspended from an axle.

In either case, the men struck the target as hard as they could both from a standing posture and on their hands and knees.

The findings: for all punching angles, men hit with far more force when they were standing, and from both postures they could hit over twice as hard downward as upward.

Humans: Two-Legged Punching Apes?

The transition from four-legged to two-legged posture is a defining point in human evolution, yet the reason for the shift is still under debate. Darwin thought that our ancestors stood up so they could handle tools and weapons. Later scientists have suggested that bipedalism evolved for a host of other reasons, including carrying food, dissipating heat, efficient running and reaching distant branches while foraging in trees.

"Others pointed out that great apes often fight and threaten to fight from bipedal posture," says Carrier. "My study provides a mechanistic explanation for why many species of mammals stand bipedally to fight."

Carrier says many scientists are reluctant to consider an idea that paints our ancestors as violent.

"Among academics there often is resistance to the reality that humans are a violent species. It's an intrinsic desire to have us be more peaceful than we are," he says.

Nevertheless, human males and their great ape cousins – chimpanzees, gorillas and orangutans – frequently fight each other for territory and access to females.

The most popular theories about why we became bipedal are based on locomotor advantages – increases in the efficiency of walking and running. However, research shows upright posture is worse for locomotion, contrary to what Carrier initially believed.

"If you're a chimpanzee- or gorilla-type ancestor that is moving on the ground, walking bipedally has a cost," he says. "It's energetically more expensive, it's harder to speed up and slow down, and there are costs in terms of agility. In every way, going from four legs to two is a disadvantage for locomotion. So the selective advantage for becoming bipedal, whatever it was, must have been important."

Nearly all mammals, including chimps and gorillas, move on all fours when they run or cover long distances on the ground. On the other hand, all sorts of four-legged animals stand up and use their front legs to fight. They include anteaters, lions, wolves, bears, wolverines, horses, rabbits and many rodents and primates.

Carrier believes that the usefulness of quadruped forelegs as weapons is a side effect of how forelegs are used for walking and running. When an animal is running with its body positioned horizontally, the forelegs strike down at the ground. By lifting the body to a vertical posture, animals can direct that same force toward an opponent.

In addition, quadrupeds are stronger pulling back with their forelimbs than pushing forward. That translates to a powerful downward blow when they rear up on their . These advantages, which grow directly out of four-legged movement, can be used most effectively by an animal that can stand easily on two legs.

Carrier predicted that animals would hit harder with their forelegs when their bodies were held upright than when they were horizontal, and that they would hit harder downward than upward. Although it would be ideal to test these hypotheses with four-legged animals, humans should still possess the advantages that led our ancestors to stand upright, and they are more practical test subjects.

The results were exactly what Carrier expected. Men's side strikes were 64 percent harder, their forward strikes were 48 percent harder, their downward strikes were 44 percent harder, and their upward strikes were 48 percent harder when they were standing than when they were on their hands and knees. From both postures, subjects delivered 3.3 times as much force when they hit downward rather than upward.

Do Women Want Men Who Can Fight?

While Carrier's study primarily deals with the evolution of upright , it also may have implications for how women choose mates. Multiple studies have shown that women find tall men more attractive. Greater height is also associated with health, social dominance, symmetrical faces and intelligence in men and women. These correlations have led some scientists to suggest that women prefer tall men because height indicates "good genes" that can be passed on to offspring. Carrier believes there is more to it.

"If that were the whole story, I would expect the same to be true for men – that men would be attracted to tall women. But it turns out they're not. Men are attracted to women of average height or even shorter," he says.

The alternative explanation is that tall males among our ancestors were better able to defend their resources, partners and offspring. If males can hit down harder than they can hit up, a tall male has the advantage in a fight because he can punch down to hit his opponent's most vulnerable targets.

Carrier certainly isn't saying women like physically abusive men or those who get into fights with each other. He is saying that women like tall men because tallness is a product if the evolutionary advantage held by our ancestors who began standing upright to fight.

"From the perspective of sexual selection theory, women are attracted to powerful males, not because powerful males can beat them up, but because powerful males can protect them and their children from other males," Carrier says.

"In a world of automatic weapons and guided missiles, male physical strength has little relevance to most conflicts between males," he adds. "But guns have been common weapons for less than 15 human generations. So maybe we shouldn't be surprised that modern females are still attracted to physical traits that predict how their mates would fare in a fight."

Explore further: Rock-paper-scissors model helps researchers demonstrate benefits of high mutation rates

Related Stories

The cost of being on your toes

Feb 12, 2010

Humans, other great apes and bears are among the few animals that step first on the heel when walking, and then roll onto the ball of the foot and toes. Now, a University of Utah study shows the advantage: ...

Lizards pull a wheelie

Jun 13, 2008

Why bother running on hind legs when the four you've been given work perfectly well? This is the question that puzzles Christofer Clemente. For birds and primates, there's a perfectly good answer: birds have converted their ...

Women feel pain more often than men

Jul 06, 2005

Women feel pain more than men -- the opposite of widely held beliefs that men are more susceptible to pain, British researchers at the University of Bath say.

Study Sheds Light on Why Humans Walk on Two Legs

Jul 20, 2007

A team of anthropologists that studied chimpanzees trained to use treadmills has gathered new evidence suggesting that our earliest apelike ancestors started walking on two legs because it required less energy ...

Recommended for you

Plants with dormant seeds give rise to more species

3 hours ago

Seeds that sprout as soon as they're planted may be good news for a garden. But wild plants need to be more careful. In the wild, a plant whose seeds sprouted at the first warm spell or rainy day would risk disaster. More ...

Researchers successfully clone adult human stem cells

6 hours ago

(Phys.org) —An international team of researchers, led by Robert Lanza, of Advanced Cell Technology, has announced that they have performed the first successful cloning of adult human skin cells into stem ...

User comments : 28

Adjust slider to filter visible comments by rank

Display comments: newest first

spectator
3.8 / 5 (5) May 18, 2011
You're joking, right?

You people are absolutely ignorant.

Any person who has even so much as heard of boxing, wrestling, or mixed martial arts would already know this.

Certainly any person who has ever actually been in a fight or a sparring match could have told you this as well.

Depending on the exact height of an individual, the ideal stance for maximum power in a punch is feet shoulder width apart in both dimensions, give or take a few inches.

This is not an "accident" nor an "evolution". The human body was designed for the upright position.

By comparison, a horse can kick the living hell out of you from a horizontal position.

Moreover, if a human is doing punches or hammerfist strikes downward they add their weight to the force of their muscles, which increases the power of the blow.

This is introductory martial arts. You don't get past white belt without knowing this "baby stuff".

Educated morons.
DontBeBlind
2.7 / 5 (3) May 18, 2011
You're joking, right?

You people are absolutely ignorant.

Any person who has even so much as heard of boxing, wrestling, or mixed martial arts would already know this.

Certainly any person who has ever actually been in a fight or a sparring match could have told you this as well.

Depending on the exact height of an individual, the ideal stance for maximum power in a punch is feet shoulder width apart in both dimensions, give or take a few inches.

This is not an "accident" nor an "evolution". The human body was designed for the upright position.

By comparison, a horse can kick the living hell out of you from a horizontal position.

Moreover, if a human is doing punches or hammerfist strikes downward they add their weight to the force of their muscles, which increases the power of the blow.

This is introductory martial arts. You don't get past white belt without knowing this "baby stuff".

Educated morons.


100 pct correct!
Doug_Huffman
1.8 / 5 (4) May 18, 2011
You're joking, right?
The human body was designed for the upright position...Educated moron.
Begs the questions, modus ponens, what's human, what's design? What's the use of educating morons?
dogbert
3.5 / 5 (6) May 18, 2011
The most popular theories about why we became bipedal are based on locomotor advantages increases in the efficiency of walking and running. However, research shows upright posture is worse for locomotion, contrary to what Carrier initially believed.


Wrong. Human beings are cursorial hunters well adapted to running upright. Few animals are our equal in this. Human beings can run a horse to the ground.
Doschx
5 / 5 (3) May 18, 2011
You're joking, right?
...
Educated morons.

1.) Which came first, walking upright or boxing/martial arts?
2.)The horse kick: yes a horse can kick the piss out of something horizontally, but it can also rear up and trample something with its front hooves. Which impact carries more force? Good possibility that the outcome would defend this article.
3.) I bow to your better understanding but it would seem reasonable that for fights between laymen overwhelming force trumps any kind of amateurish form.

Also, using only humans in this experiment skews the results as humans have gone through life upright, it is the only stance most of them can understand or conceive. To suddenly force them to go to all fours and count their strikes as equal to upright ones doesn't seem experimentally sound. It's like giving an archer a gun and a sniper a bow and expecting them to be as competent as the other person was with their weapon of choice.

That's all I got right now.
Deadbolt
1 / 5 (1) May 18, 2011
Damage isn't just determined by force though. It's where that force is directed.

If I strike you with an upwards elbow under the jaw, it is going to do more damage than a downwards elbow on the skull. A side-on hook attack would do even more damage than either, because it would lever the jaw, and the worst direction for the brain to receive G's is sideways on, or torsion, where the two halves of the brain will be separated and then squished. This is why hitting to the jaw with a hook is known as hitting "the button" in fighting.

I also have to wonder why you hardly ever see downwards blows when you see two average guys fight. It's usually instinctive swinging hooks from side-on from what I've seen.
spectator
not rated yet May 18, 2011
Deadbolt:

It really depends. Different unskilled fighters have different unskilled forms.

To tell the truth, almost every "unskilled" street fight or school yard fight I ever witnessed consisted of both parties throwning unskilled hammerfist strikes and maybe some hooks.

Sometimes focused intent is more important than marginal skill advantages, especially when neither fighter is particularly skilled anyway.

In Boxing, hammerfist strikes are banned because they are unnecessarily damaging.

Actually, the overhand "haymaker" hammerfist is statistically one of the more common unskilled attacks which martial artists train their students against. However, it is easily thwarted by a moderately skilled outside overhead circle block, which gives the skilled defender a natural advantage, and sets up an arm bar into a rear naked choke. With an inside overhead circle block it sets up your choice of a chop to an unprotected throat, or an instant kill reverse neck breaker.
eachus
5 / 5 (1) May 18, 2011
Lol! They are totally missing two things. First, why is tall better? Not because it gives you an advantage in a face-to-face fight. There skill, weight, speed, etc., will all be factors in the outcome.

But take a short victim and have a taller man approach from behind. There are too many choices to enumerate here of attacks which give the attacker an overwhelming advantage. Switch roles, and without a sharp implement, the short attacker has no easy approach. (Yeah, a martial arts expert would try a leg sweep. If you have a sharp implement and if the taller man is bending forward at the neck there is a killing blow, if you know what you are doing.)

Second, on standing upright. Ever gone hiking in the mountains? Even a novice will pick out a walking stick and use it. It allows you to use your upper body strength when climbing. Of course, such a stick has other advantages to. But it is very hard to carry on all fours. ;-)
spectator
not rated yet May 18, 2011
So in a nutshell, that is why you don't see two skilled professional fighters throwing lots of hammerfists as a primary attack.

It's banned in boxing. However, in boxing the counter to the hammerfist, being the circle block, is also banned, as circle blocks are considered "grappling" or "trap boxing". In boxing you are not supposed to "re-direct" an attack, you can only "block".

In Mixed Martial Arts it's a low percentage strike but with high potential damage, and therefore only normally used when you already havea natural advantage, such as mounting someone on the floor, or the other person is already off balance from a previous combo, etc.

Most real street fights go to the ground within 10 to 15 seconds anyway, that is if someone isn't already knocked out by the first few strikes, because what happens is someone loses their balance, and in desperation does the best possible thing in that situation, which is to pull the other person down with them, evening the odds again.
NickFun
5 / 5 (1) May 18, 2011
So...we evolved this way because it's easier to beat the shit out of each other and women like to watch us beat the shit out of each other?
spectator
1 / 5 (2) May 18, 2011
So...we evolved this way because it's easier to beat the shit out of each other and women like to watch us beat the shit out of each other?


This is where I certainly differ from anything in this article.

"Evolution" has nothing to do with it.

The human form and human intelligence is already having a high degree of freedom in terms of functionality and problem solving both physically and mentally.

There is little to no reason or benefit for the human form to change, since humans can make tools and change their environment.

Due to farming, we must neither run from predators nor chase prey. Even hunter/gatherers, such as some native American tribes, did not "chase" prey. They hunted by tracking, pattern recognition, strategy, and etc.

Due to shelter, all but the most extreme weather and disasters are but minimal influences on our lives.

These two facts have been mostly constant throughout human existence.

Squirrel
1 / 5 (1) May 19, 2011
A short upright individual with a stone will be beat a taller one without one. If they both have stones, then size does not come into it with contest being determined by accuracy in aim from a distance.
snu
5 / 5 (2) May 19, 2011
The most popular theories about why we became bipedal are based on locomotor advantages increases in the efficiency of walking and running. However, research shows upright posture is worse for locomotion, contrary to what Carrier initially believed.


Wrong. Human beings are cursorial hunters well adapted to running upright. Few animals are our equal in this. Human beings can run a horse to the ground.


Most horses are quite a bit faster than most humans. Most quadrupeds bigger than a cat are faster than humans.

The amazing long distance running ability of humans comes from our ability to sweat, not bipedality. Animals with fur overheat and have to stop to cool down. Humans are very efficient at cooling themselves. Try to run a marathon in a fur coat!
dogbert
1 / 5 (1) May 19, 2011
The amazing long distance running ability of humans comes from our ability to sweat, not bipedality. Animals with fur overheat and have to stop to cool down. Humans are very efficient at cooling themselves. Try to run a marathon in a fur coat!


It is certainly more than the ability to sweat. Horses sweat and dogs are our equal in long distance running. Dogs have a lot of fur and do not sweat well.
Shaffer
1 / 5 (1) May 19, 2011
What's the use of educating morons?


There is none, yet we do it every day...
Modernmystic
1 / 5 (1) May 20, 2011
FTA:
walking bipedally has a cost," he says. "It's energetically more expensive,


Patently false, walking bipedally uses about half the energy as quadruped walking.
snu
not rated yet May 20, 2011
The amazing long distance running ability of humans comes from our ability to sweat, not bipedality. Animals with fur overheat and have to stop to cool down. Humans are very efficient at cooling themselves. Try to run a marathon in a fur coat!


It is certainly more than the ability to sweat. Horses sweat and dogs are our equal in long distance running. Dogs have a lot of fur and do not sweat well.

It's true other animals than humans sweat also. Horses and many other are not very efficient at sweating because of the fur. It slows down the evaporation of water from the skin. Dogs are good at evaporating water through their tongue and breathing. Human sized animals have more skin/volume than horse sized animals, which is also an advantage for us.
snu
not rated yet May 22, 2011
FTA:
walking bipedally has a cost," he says. "It's energetically more expensive,


Patently false, walking bipedally uses about half the energy as quadruped walking.

Do you have any proof of that? I'd be interested in reading a study about it.
ubavontuba
1 / 5 (3) May 22, 2011
Have women always preferred tall men? And, have men always preferred small women?

I ask because this seems contradictory to the fact that humans are the least sexually size dimorphic species of the great apes.

http://web.missou...s/sd.htm

Note: The above reference includes gibbons which are considered "lesser apes" and are the least sexually size dimorphic of all the apes.

http://en.wikiped...i/Gibbon

Eikka
1 / 5 (1) May 22, 2011
The point was that -going- from quadrupedal to bipedal walking has a huge cost disadvantage.

Once you are bipedal, you can get good at it, but there's an entry cost so you can't explain going bipedal simply by its efficiency. It doesn't save you anything immediately.

Hence there's all these "water ape" theories that try to find other use for walking on two legs before it starts to consume less energy - like wading in shallow water.

Modernmystic
3 / 5 (2) May 22, 2011
FTA:
walking bipedally has a cost," he says. "It's energetically more expensive,


Patently false, walking bipedally uses about half the energy as quadruped walking.

Do you have any proof of that? I'd be interested in reading a study about it.


http://en.wikiped..._note-31

http://www.anthro...ism1.pdf

Five minutes on google...
snu
not rated yet May 23, 2011
If being a biped means you are both better at fighting and use less energy when moving, wouldn't it mean ALL animals would be bipeds? Or atleast a significant portion?
dogbert
1 / 5 (1) May 23, 2011
If being a biped means you are both better at fighting and use less energy when moving, wouldn't it mean ALL animals would be bipeds? Or at least a significant portion?


Only if the processes which result in diversity are expected to be goal oriented.

Note also that a lot of animals are bipedal. Birds, kangaroos, gerbils for example.
PaulieMac
not rated yet May 23, 2011

Patently false, walking bipedally uses about half the energy as quadruped walking.

Do you have any proof of that? I'd be interested in reading a study about it.


http://en.wikiped..._note-31

Five minutes on google...


Hmm.. The wiki article doesn't seem to adress the topic particularly(from an admittedly quick skim).

The second article gives your statement only slim support, in that it does seem to show human bipedalism as more efficient at walking speeds than chimpanzee locomotion, while apparently conceding that non-homonoid quadrapedalism is generally at least equally efficient...

Probably, the truth will be a mixture of small advantages accruing. The freeing of the hands, an increase in energy utilisation, elevation of the eyes allowing a better view of the surroundings, all conferring some statistical boost to survival...
Modernmystic
3 / 5 (2) May 23, 2011
Hmm.. The wiki article doesn't seem to adress the topic particularly(from an admittedly quick skim).


It wasn't supposed to, I pointed to you at the sources at the end of the article 32, and 33 if I remember correctly.

The second article gives your statement only slim support, in that it does seem to show human bipedalism as more efficient at walking speeds than chimpanzee locomotion, while apparently conceding that non-homonoid quadrapedalism is generally at least equally efficient...


No the conclusion of the article is that bipedal walking bestowed and energy advantage to hominids. Re-read it. I got excellent marks in kinesiology and bio-mechanics in college. This is elementary stuff and has been known for a long time. If I can find a medical journal article I'll provide it if you promise to buy it and read it.
PaulieMac
not rated yet May 23, 2011
Well, quoting the article:
(snip snip) 1)human bipedalism is at least as efficient as typical mammalian quadrupedalism ad 2) human gait is much more efficient that bideal or quadrupedal locomotion in the chimpanzee


It's an interestign article. Their approach of comparing efficiency within the hominid branch makes good sense; much more useful in terms of figuring out evolutionary advantage than comparing human gait to, say, that of an ungulate.

And apologies but I shan't promise to buy the journal; while I find the topic to be an interesting one, I don't find it quite that engrossing! :)
jmcanoy1860
not rated yet May 24, 2011
I'm 6'8" and I can tell you that my nuts are at the right height for hitting by any kid tall enough to perform a "run and hug". Therefore, I disagree with the premise that standing up to fight is an advantage for taller men. Sure reach, weight, power blah blah blah. I've got that. One square nut shot and those things disappear at slightly less than an acceleration of g.
Truthforall
not rated yet Jun 14, 2011
The correct defensive posture in a fight is to crouch low and reduce your exposure. You come in low not high unless you are kicking. Bent knees would give good mobility and would provide good momentum behind any strike.
To bring your fist high and strike down is to expose you chest and lower body. Not recommended against any thing with horn.
For early hunters, the firm spear thrust will be slightly up with planted feet. A down thrust is only effective on small games. On large animal the weight of the human body counts for nothing, remember that our ancesters were smaller than us. Against bear, boar, elephant(mesodon) and larger animals, we need the charge of the animal to bring home the killing thrust with the spear butt planted.
A throwing spear would benefit from the body height. But with introduction of the bow, this advantage is minimal.
The research should consult expert hunters from Africa and New Guinea.

More news stories

Researchers successfully clone adult human stem cells

(Phys.org) —An international team of researchers, led by Robert Lanza, of Advanced Cell Technology, has announced that they have performed the first successful cloning of adult human skin cells into stem ...

Researchers develop new model of cellular movement

(Phys.org) —Cell movement plays an important role in a host of biological functions from embryonic development to repairing wounded tissue. It also enables cancer cells to break free from their sites of ...

Male monkey filmed caring for dying mate (w/ Video)

(Phys.org) —The incident was captured by Dr Bruna Bezerra and colleagues in the Atlantic Forest in the Northeast of Brazil.  Dr Bezerra is a Research Associate at the University of Bristol and a Professor ...

Plants with dormant seeds give rise to more species

Seeds that sprout as soon as they're planted may be good news for a garden. But wild plants need to be more careful. In the wild, a plant whose seeds sprouted at the first warm spell or rainy day would risk disaster. More ...