The nose shape gene inherited from Neanderthals

Fanny Trifilieff: Can you tell us a little about your research?

Pierre Faux: It's a long-standing collaboration between universities: University College of London, Fudan University in Shanghai, the Open University of London, and Aix-Marseille Université via the ADES laboratory. This research concerns the CANDELA project developed by Professor Andres Ruiz Linares, whose main aim was to study the physical appearance of individuals and understand which genes might be involved. It was carried out in five Latin American countries - Mexico, Colombia, Peru, Chile and Brazil - on a total of 7,000 people photographed, from whom a DNA sample was taken to find out about their genome. We used software that automatically places landmarks on the faces and measures the distances between certain points, such as the tip of the nose or the edge of the nostril. These measurements are then correlated with different regions of the genome. The idea was to identify candidate genes that might be responsible for the phenotype studied via the measurements. Here, we found that in one particular region of the genome, it was a short piece of DNA, probably inherited from Neanderthals, that would contribute to increased nose height.

F.T: Why did you choose to study volunteers from Latin America?

P.F: In this type of study, where correlations are established between characteristics (physical or otherwise) and genome variability, the majority are carried out on European or Asian populations. This is often due to the location of the research centers, which then sample the surrounding populations. Or research projects are simply linked to issues or phenotypes present in these particular populations. As a result of the successive migrations of modern man since leaving Africa, when studying Latin Americans, we find not only mutations inherited from Europeans, but also from the original Amerindians, as well as those of African populations. This population remains under-studied. When CANDELA was launched, other research groups interested in facial features had only worked on European populations.

F.T: What evolutionary advantage would this gene have provided?

P.F : Everything remains speculative, based on three hypotheses. Did we really inherit this piece of DNA from the Neanderthals? We're 99% certain, because we can compare it with existing Neanderthal genomes that have already been sequenced, and it's there. The second hypothesis concerns the role of this piece of genome on the phenotype studied. This is much more speculative. We know that certain traits are polygenic, i.e. they are influenced by several genes. The candidate gene identified here may not be the only gene responsible for nose shape, and we can't experiment with everything. Finally, we might think that since our noses help us to regulate air temperature and humidity, different nose shapes might be better suited to the climates in which our ancestors lived. The gene we've identified here could have been inherited from Neanderthals to help humans adapt to colder climates when our ancestors left Africa. But we could also be completely wrong. Homo sapiens may well have kept this piece of gene because it is responsible for another characteristic that has completely eluded us.