Why were Neanderthals’ faces different from our own?

Reconstructions of a Neanderthal man and woman in the Neanderthal Museum in Mettmann, Germany. Photography: Martin Meissner / AP

Compared to modern man, Neanderthal man had large eyebrows, a big nose and a long, curved face. With the help of 3D computer modelling, an international team of scientists are now suggesting several hypotheses which could explain these physical differences. 

Neanderthals and modern humans -or Homo sapiens -diverged from a common ancestry around 700,000 to 900,000 years ago, with each one then following its own evolutionary path. One of these paths however reached an impasse. While our ancestors continued to evolve in Africa, the Neanderthals migrated towards Eurasia, where they lived for hundreds of thousands of years, throughout several ice ages. During this time, Neanderthals probably developed special physical characteristics which helped them survive difficult conditions.

We know that Neanderthals did not look like us. Although they were technically human and bestowed with similar characteristics to us, they were smaller, more robust and physically stronger. But they also had distinctive facial features, with thick eyebrows, small chins, wide foreheads and large noses. Some of these characteristics, such as the forehead and the chin, were probably inherited from their ancestors. But others are so unusual that paleontologists estimate that they must have evolved them for a particular reason: for surviving the cold, according to a new study published on the 4th April in Proceedings of the Royal Society B.

Credits: Pixabay/Tpsdave

Before this new study, scientists had developed a theory to explain Neanderthal’s distinctive faces. One hypothesis was that the facial structure allowed Neanderthals to have a very strong bite, using their teeth as tools -or a sort of third hand -which of course put a lot of pressure on the front of the jaw. This theory was given great credit, as fossil evidence showed that Neanderthal teeth were very worn down.

Additionally, the large nasal cavities could have allowed them to engage in a type of “turbo breathing”, which gave them a few extra breaths of air during intensive work, or while burning significant quantities of calories to keep the body warm. In fact, it has been estimated that Neanderthals burned on average 3,360 to 4,480 calories per day, which is huge compared to modern humans, who tend to burn between 2,000 and 3,000 calories a day.

In order to test out these hypotheses, an international team of researchers directed by Stephen Wroe of the University of New England in Australia, used scanners to construct three-dimensional computer models of Neanderthals, modern humans and a group of extinct humans, Homo heidelbergensis -a possible common ancestor of both. The team added this ancient human to the mix to see which traits could have existed in both Neanderthals and modern humans before they diverged. The researchers put the models through various stress tests and air-flow assessments.

Initially, the models showed few differences in chewing abilities between the three species of humans. In fact, modern humans appeared to be better equipped than Neanderthals in terms of biting ability. The first hypothesis is thus seriously cast into doubt. On the other hand, it was shown that the Neanderthals’ nasal cavities, and those of modern humans, better supported breathing than those of Homo heidelbergensis, which suggests that the both species evolved to resist cold and dry climates. However, the scientists noticed that the Neanderthals could move more air through their nasal passages than the other species.

Thus, the study appears to rule out the theory that the Neanderthal face shape evolved to facilitate a powerful bite. Neanderthals are distinguished by their ability to move around and take in large volumes of air via their nasal passages. Their lifestyle, based on the active search for food in a cold and dry climate, appeared to necessitate this. Neanderthal nasal passages were around 29% larger than those of modern humans, and were able to circulate air at a higher rate.