People with particular Neanderthal DNA fragments, who have slightly less rounded heads, have given researchers genetic clues into human brain evolution.
There are humans alive today with European ancestry who carry rare fragments of Neanderthal DNA in their genomes, who researchers have studied for insights into human brain evolution.
How can modern humans carry Neanderthal DNA?
The cause of the existence of Neanderthal DNA in their genomes is interbreeding between Neanderthals and the ancestors of modern Europeans. Different people carry different fragments of this DNA, which are scattered through the genome.
Researching human brain evolution
Phillip Gunz, a paleoanthropologist at the Max Planck Institute for Evolutionary Anthropology, co-led the study with Amanda Tilot of the Max Planck Institute for Psycholinguistics. The research team analysed cranial shape and identified Neanderthal DNA in a large sample of humans using MRI brain scans and genetic information for approximately 4500 people.
They used computer tomographic scans to compute the endocranial shape differences between modern human skulls and Neanderthal fossils. They used this contrast to assess endocranial shape in the thousands of MRI scans of living people.
Gunz said: “We captured subtle variations in endocranial shape that likely reflect changes in the volume and connectivity of certain brain areas.”
Tilot added: “Our aim was to identify potential candidate genes and biological pathways that are related to brain globularity.”
They used information from sequenced genomes of ancient Neanderthal DNA to identify fragments of it in living humans on chromosomes 1 and 18 that correlated with reduced cranial roundness.
Senior author Simon Fisher, a geneticist at the Max Planck Institute for Psycholinguistics, explained: “The Neandertal variants lead to small changes in gene activity and only push people slightly towards a less globular brain shape. This is just our first glimpse of the molecular underpinnings of this phenotype, which is likely to involve many other genes.”