The most noticeable difference between the modern human face and that of the hunter-gatherers, who lived on Earth over 200,000 years ago, is the forehead. While we now have flat, smooth foreheads with visible eyebrows, our ancestors sported a pronounced brow ridge. Experts have always believed that the thick rim, and the evolution to the beautiful tufts of facial hair, served a physiological function. Now, a team of scientists from UK's University of York and Portugal's Algarve University suggest that the facial features help with our social relationships.
The team has come up with a new argument for the need of the unique facial feature. They suggest it serves a social purpose rather than a mechanical one. The scientists assert that similar to the antlers on a stag, the jutting brow ridge signaled dominance and aggression in our early ancestors. However, as we switched from being hunter-gathers to farmers, our lifestyle changed dramatically, and the need to create more extensive social networks increased.
Thanks to the dietary variety and the lower physical effort required by the agricultural lifestyle, our faces gradually became smaller, causing the jutting brow ridge to transform into a flatter forehead. The need for social communication rather than intimidation started to show in the form of more expressive eyebrows that could facilitate critical social signals in modern humans, like expressions of surprise or anger.
Spanish paleontologist Markus Bastir, who was not part of the study, says that while the theory does open up "exciting prospects for future research," it should be taken with a grain of salt. That's because Kabwe 1, the specimen used to create the 3-D model, is missing the mandible or lower jaw. Professor O'Higgins and his team, therefore, had to substitute it with a jawbone from a Neanderthal, which is a different species. Bastir believes that the substitution may have altered the results of the model and bite stresses. Regardless of the real reason for the brow ridge's evolution, we all have at some point experienced the power of the raised eyebrow!
