Why do so many men sport hipster beards? It's because they're trying to look attractive to women and dominant to other men — according to science.

A new study on monkeys conducted by researchers at the University of Western Australia reveals that beards could be like biological badges of honor. The more a primate has to deal with rivals, the more ornate his features become.

Lead researcher Cyril Grueter and his team explored the idea that male primates have developed these ostentatious "badges" in large societies over time. Proboscis monkeys have extended noses, orangutans have cheek flanges and humans have beards.

For the purpose of the study, the researchers observed nearly 154 primate species, taking account of their facial hair and other body "ornaments." They discovered that in large societies where physical and social tussle is commonplace, the badges of honor were more flamboyant.

By contrast, species who lived in smaller groups did not require the development of badges because recognition of the individual was higher. Moreover, a greater level of interaction with others enabled the males to assert their status, strength, and so forth, in a more sophisticated manner.

"When you live in a small group where everyone knows everyone because of repeated interactions, there is no need to signal quality and competitiveness via ornaments," noted Grueter.

"In large groups where individuals are surrounded by strangers, we need a quick reliable tool to evaluate someone's strength and quality, and that's where these elaborate ornaments come in. In the case of humans, this may also include phenotypic extensions such as body decoration, jewelery and prestige items."

These badges also serve to make the male more attractive to females. For instance, in rhesus monkeys, males who have darker red faces get higher attention from the females at the time of mating season.

The researchers explained that rivalry amid males could have led to the development of these features, as the individuals who have them appear to be more prevailing and aggressive than those lacking a so-called badge.

The ornamentation in primates – or hipster beards in human men – reflects the amplified signals of individual desire to assert oneself and gain prominence over others in large, complex societies.

The study was published in the journal Evolution and Human Behavior.

Photo Credit: Iulia Pironea | Flickr