Do beards signal status in big societies?

Beards may be back in fashion because men need more ostentatious body ornaments to show where they fit in, as society becomes more competitive and complex, new research suggests.

According to an international group of researchers led by The University of Western Australia's Cyril Grueter, the more competition a primate has to deal with, the more flamboyant he gets.

In a paper recently published online in Evolution and Human Behavior, they explored the hypothesis that in big, multi-level societies, male primates have developed more conspicuous "badges".

Examples include the spectacularly colourful face make-up and rear ends of mandrills, which move in hordes of up to 800, the elongated noses of proboscis monkeys, cheek flanges in orangutans - and possibly beards in humans.

The distinct physical traits benefit males in large and complex social organisations by signalling their identity, rank, dominance and attractiveness, researchers say.

Species that live in smaller groups, on the other hand, have less need for badges.

"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," Dr Grueter said.

"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."

Dr Grueter said men with beards were perceived as being more masculine and more dominant than bare-faced men, "so it's possible that male facial hair is also the outcome of inter-male competition".