New Study Says Our Eyebrows Evolved to Give Humans More Subtle Communication Skills
The general consensus is that about 55 percent of communication is non-verbal: subtle things like facial expressions and one's posture can communicate volumes, and even something as innocuous as an eyebrow raise can be loaded with meaning. A new study says eyebrows are an especially interesting case—their rise to prominence in human communication may have marked not only a change in the way ancient humans expressed themselves, but the shape of our skulls.
Researchers at the University of York studied the skull of Homo heidelbergensis, an ancestor to homo sapiens, in order to test a few hypotheses about our ancestors' thick brow ridges.
As you probably know, many human ancestors' skulls had a prominent brow that jutted out over the eyes, but the reason for it has remained a mystery: some anthropologists speculated that it developed simply to divide the braincap from the lower portion of the skull, while others thought it might have helped the skull endure the chewing motions with the jaw.
The researchers found that neither of these hypotheses fit the bill for why the brow was so thick, but it may have been a mark of dominance, used to intimidate others. Either way, those big brows seem to have prevented our ancestors from using their eyebrows to express themselves in any significant way.
As the shape of the skull changed, however, the role of the eyebrows may have changed, too.
According to Paul O'Higgins, a professor of anatomy: "We traded dominance or aggression for a wider palette of expression. As the face became smaller and the forehead flattened, the muscles in the face could move the eyebrows up and down and we could express all these subtler feelings."
This may have turned out to be an advantage when it came to cooperation, says Penny Spikins, a paleolithic archaeologist: "We moved from a position where we wanted to compete, where looking more intimidating was an advantage, to one where it was better to get on with people, to recognise each other from afar with an eyebrow flash, and to sympathise and so on."
The research is still speculative, but it's interesting to think about the next time you're watching a room full of friends talk to one another—instead of listening to the conversation, watch their eyebrows. That's not weird, is it?