Last year mathematics helped answer the conundrum of why hipsters all look the same, and now evolutionary biology has come to the fore to explain why they grow beards.

The answer is apparently because all men, hipsters included, feel under threat from other men, and growing a beard is an attempt to appear as aggressive and dominant as possible.

Researchers looked at more than 100 species of primate and found that the males of the species develop "badges" to stand out, such as the elongated noses of proboscis monkeys, cheek flanges in orang-utans, upper-lip warts in golden snub-nosed monkeys, or beards in hipsters.

It is understood that male primates believe these badges can help give them an edge over other males in attracting females.

Scientists, from the University of Western Australia, also found that the more conflict-ridden and competitive a society, the more conspicuous these badges would be.

Lead study author Dr Cyril Grueter wrote: "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. 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, jewellery and prestige items."

More: [The formula that explains why all hipsters look the same]3