Can you tell what someone’s thinking from a raised eyebrow? Research conducted at the University of York suggests that humans may have lost their prominent brow bone as social communication became more important than brute strength. Paul O’Higgins, lead author of the study, argues that “we traded dominance or aggression for a wider palette of expression”; as the strong brown bone receded, our facial muscles enabled us to express a wider range of emotion, facilitating nuanced communication. According to this hypothesis, somewhere along the line in human evolution we changed from a species where the strongest and most intimidating got ahead to a species which favoured easy reading of expression and therefore cooperation and empathy for the emotions of other individuals.

In searching for an explanation for why ancient humans originally had these prominent brows, scientists considered the possibility that the extra bone was needed to fill the gap between the protruding face and the braincase. However, they quickly found that there was far more bone present than would have been needed to fill this gap. They also considered how the physical stress of chewing may necessitate a stronger facial structure, but this too proved an unfruitful line of enquiry. Robin Dunbar, professor of evolutionary psychology at the University of Oxford, points out the somewhat unusual fact that while eyebrows are an important part of human communication, other primates appear not to use them much. He speculates that the nuanced use of eyebrows may coincide specifically with the need for complex communications that developed relatively late in human evolution, and therefore is not as relevant to other species, even fairly sophisticated primate species. However, Dr. Rachael Jack from the University of Glasgow points out that many different facial muscles would have contributed to the development of communication, so the eyebrows may not in themselves be as significant as research of this kind suggests.  

Applicants for Biology or Natural Sciences, students wishing to study Archaeology and Anthropology,  or those interested in evolutionary psychology and may want to familiarise themselves with past and current research on human evolution. They should consider the role that communication plays in the group life of different species, and how this social component influences the development of these species.

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