Human men evolved to be good at punching in order to win fist fights with sexual competitors so that they could breed with women.
A study found that men throughout all of time have been forced to scrap in order to win the affections of women and have children.
This pressure has caused male bodies to change, becoming more powerful and explosive when throwing a swift right hook.
It has led to what is known as sexual dimorphism — physical differences between males and females in a species.
Over thousands of years, men unable to fight were slowly weeded out of the gene pool and, as a result, modern males are accomplished at hand-to-hand conflict.
The end result is that male bodies became specifically tailored by evolution to be good at punching.
For example, researchers in the US found that the weakest man punches harder than than the strongest woman in tests.
Researchers write in the study: ‘Sexual dimorphism often arises from selection on specific musculoskeletal traits that improve male fighting performance.
‘In humans, one common form of fighting includes using the fists as weapons.’
Men’s average power during a punching motion test was 162 per cent greater than females, they found.
However when it came to spear throwing, the difference was not as great, implying evolution built men to fight, not to hunt.
Professor David Carrier at the University of Utah said: ‘This is a dramatic example of sexual dimorphism that’s consistent with males becoming more specialised for fighting and males fighting in a particular way, which is throwing punches.
‘There are two sides to who we are as a species.
‘If our goal is to minimise all forms of violence in the future, then understanding our tendencies and what our nature really is, is going to help.’
The researchers measured the punching strength of 20 active men and 19 active women by rigging up a hand crank that would mimic the motions of a punch.
The men and women would also pull a line over their head forward in a motion similar to throwing a spear.
This was to test the hypothesis that males’ upper body strength may have developed for the purpose of spear hunting.
But this test found the sexes did not show the same difference in strength with the overhead pulling test as for ‘protracting the arm to propel the fist forward’.
This, the researchers believe, proves that the male body is designed for punching rather than throwing weapons.
Previous studies have found that, on average, males’ upper bodies have 75 per cent more muscle mass and 90 per cent more strength than females but it is not known why.
The different hand proportions are not just for manual dexterity but they also protect the hand when it’s formed into a fist, according to past studies.
Wofford College assistant Professor Jeremy Morris said: ‘The general approach to understanding why sexual dimorphism evolves is to measure the actual differences in the muscles or the skeletons of males and females of a given species, and then look at the behaviours that might be driving those differences.’
The results were published in the Journal of Experimental Biology.