Study: Early man stood on 2 legs to compete for women

Study: Early man stood on 2 legs to compete for women


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SALT LAKE CITY — Men do crazy things to impress women. Could that be the reason ancient man first stood up on two legs? A new University of Utah study suggests that, or at least supports the idea that man's ape-like ancestors began walking upright to be better at killing and competing for females.

University of Utah biology professor David Carrier conducted the study, "The Advantage of Standing Up to Fight and the Evolution of Habitual Bipedalism in Hominins," which was published Wednesday in the online Public Library of Science Journal. The study shows that men are able to hit objects with greater force when standing on two legs — as opposed to being on all fours — and when hitting in a downward direction.


The performance advantage when striking from an upright stance is consistent with the hypothesis that our family of great apes stood up on our hind legs in response to selection for fighting ability in males.

–David Carrier


"The performance advantage when striking from an upright stance is consistent with the hypothesis that our family of great apes stood up on our hind legs in response to selection for fighting ability in males," Carrier, who is currently on sabbatical in England, said via email.

While humans are among the minority of mammals that habitually walk on two legs, Carrier observed that many species — such as canines, felines, bears and horses — stand on their hind legs when fighting. He hypothesized that a taller fighting stance would give a competitive advantage among males and could have been a catalyst behind man's evolution to an upright posture.

"Intense male-male fighting characterizes the mating systems of four of five species of great apes, our closest living relatives," Carrier said. "Humans are also a relatively violent species and most of this violence is perpetrated by men. These observations, plus the performance advantage demonstrated in this study, suggest that male-male fighting over females may have been one of the factors that led to the evolution of (walking on two legs)."

To conduct the study, Carrier enlisted the help of local boxers and martial artists. Punching bags were equipped with accelerometers to measure sideways and forward strikes, and weighted levers were used to measure upward and downward blows. For each target, participants were asked to strike with full strength from both a standing position and from all fours. Downward strikes hit the hardest, and in each case, a standing position resulted in greater force.

In his work, Carrier references multiple studies showing that women are attracted to taller men. These studies had findings that tall men receive more responses to dating advertisements. Women report dating tall men more often than short and that height is associated with cognitive abilities, financial success, health, social dominance and intelligence.

Carrier suggests that this attraction is a remnant of the evolutionary advantage of standing upright. If, as his study supports, males have more downward force than upward, a tall male would have the upper hand in physical conflicts and be better equipped to defend resources, mates and offspring.

Carrier said his study challenges the set of ideas that humans are intrinsically peaceful or that the high levels of violence in modern society are a result of today's lifestyles.

"Many people, in and outside of biology, are reluctant to face how violent humans can be," Carrier said. "It is simply easier to assume that acts of violence represent abnormal behavior than to face the scary possibility that aggressive behavior is natural for our species."

Not only could aggressive behavior be natural, but potentially rooted in human physical evolution and attraction. One thing Carrier points out, however, is that man's capacity for violence can be viewed positively as well as negatively.

"In state societies, having a short fuse is almost always viewed as a negative personality trait," Carrier said. "In contrast, in societies that have no laws or enforcement of laws an ability to respond to a threat in an aggressive way is looked at much more positively."

Carrier said studies such as his may be received with skepticism, but are important to better understand, and combat, the problems associated with human violence.

"If we want to curb violence in the future we have to acknowledge that we have a problem and this is where studies such as this one may be useful," Carrier said.

Carrier has been teaching at the University of Utah since 1995, prior to which he was an assistant professor at Brown University.

Email:benwood@desnews.com

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