People with two Neanderthal genes have heads that are flatter on top and more elongated – like those of Neanderthals themselves.
The effect is too small to be seen with the naked eye, but shows up on brain scans. The modern versions of the genes seem to make certain parts of the brain work more effectively.
Neanderthals were not the direct ancestors of our own species, but our distant cousins. They were already living in Europe by the time our ancestors arrived, about 40,000 years ago, and there seems to have been interbreeding, as most Europeans have some Neanderthal genes lurking in their DNA – between 1 and 2 per cent of the total.
Simon Fisher of the Max Planck Institute for Psycholinguistics in the Netherlands wondered if these genes would have any effect on head shape, as both Neanderthal skulls – and those of our last common ancestors with Neanderthals – are less ball-shaped than the skulls of people living today. “It’s one of the most distinctive anatomical differences,” says Fisher.
Fisher’s team scanned the skulls of nearly 4500 Europeans in a brain scanner and also sequenced their genomes to look for about 6700 fragments of DNA thought to have been passed on from Neanderthals.
Two fragments were linked with a flatter skull in the living Europeans. Both have previously been found to have a role in brain development – which makes sense as the brain’s shape affects that of the skull.
In one, the modern human version makes nerve cells better insulated in part of the brain called the cerebellum. The other gene’s modern human variant may boost nerve cell growth in a structure called the putamen.
On average, people with the Neanderthal versions might have slightly less effective cerebellums and putamens, although Fisher stresses that the effect would be too subtle to be noticeable in individuals.
(The paper may be found here: https://www.cell.com/current-biology/fulltext/S0960-9822(18)31470-2?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0960982218314702%3Fshowall%3Dtrue)