Europeans and Asians who live today carry about 2 percent of Neanderthal DNA as a result of interbreeding between human ancestors and their now-extinct evolutionary cousin, the Neanderthals.

Neanderthal Genes Inherited By Modern Humans

These inherited Neanderthal genes influence some traits in modern humans such as their ability to fight infections and vulnerability to certain diseases. Now, researchers of a new study revealed another effect of these Neanderthal genes on humans who live today.

Study researcher Philipp Gunz, a paleoanthropologist at the Max Planck Institute for Evolutionary Anthropology, and colleagues found that two pieces of Neanderthal DNA may have changed the shape of a human skull.

For their study published in the journal Current Biology, Gunz and colleagues used MRI scans to analyze the cranial shape of the head of 4,468 people in the Netherlands and Germany. They also looked at the genomes of these individuals to determine which fragments of Neanderthal DNA they carried.

The researchers then compared the shapes of the participants' brain to find out if there were Neanderthal gene variants associated with more elongated heads.

"By combining data from fossils, genetics and brain imaging we can learn something about evolutionary changes to brain development in our own species," Gunz explained.

Gene Variants Associated With Shape Of The Human Head

The researchers found two gene variants with a subtle effect on the shape of the skull. These gene variants, found on chromosomes one and 18, are linked to the expression of two nearby genes called UBR4 and PHLPP1.

The UBR4 gene helps neurons divide in the brains of children, while the PHLPP1 controls the production of the myelin, an insulation that wraps around neurons and plays an important role in long-range communication in the brain.

Disrupting the UBR4 and PHLPP1 are known to have a major effect on brain development.

The researchers said that the findings of the study do not mean that people with more elongated skull have more Neanderthal DNA. They also said that skull shape can neither explain human behavior. The study can nonetheless shed more light on how modern humans evolved their distinct brain shape.

"Our findings show how integration of fossil skull data with archaic genomics and neuroimaging can suggest developmental mechanisms that may contribute to the unique modern human endocranial shape," the researchers wrote in their study.

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