from the thank-you-Spock dept.
Submitted via IRC for AndyTheAbsurd
Having movable eyebrows – and evolving beyond the Neanderthal ridge – may have played a crucial role in early human survival.
Eyebrows, we all have them, but what are they actually for? While eyebrows help to prevent debris, sweat, and water from falling into the eye socket, they serve another important function too – and it's all to do with how they move and human connection.
[...] But our latest research may have found an answer to explain why archaic humans had such a pronounced wedge of bone over their eyes (and why modern humans don't). And it seems to be down to the fact that our highly movable eyebrows can be used to express a wide range of subtle emotions – which could have played a crucial role in human survival.
Research has already shown that humans today unconsciously raise their eyebrows briefly when they see someone at a distance to show we are not a threat. And we also lift our eyebrows to show sympathy with others – a tendency noticed by Darwin in the 19th century.
[...] The brow ridges in archaic humans also serve no obvious function in relation to chewing or other practical mechanics – a theory commonly put forward to explain protruding brow ridges. As when the ridge was taken away there was no effect on the rest of the face when biting. This means that brow ridges in archaic humans must have had a social function – most likely used to display social dominance as is seen in other primates.
For our species losing the brow ridge probably meant looking less intimidating, but by developing flatter and more vertical foreheads our species could do something very unusual – move our eyebrows in all kinds of subtle and important ways.
Although the loss of the brow ridge may have initially been driven by changes in our brain or facial reduction, it subsequently allowed our eyebrows to make many different subtle and friendly gestures to people around us.