One of the characteristics that distinguishes modern humans (right) of Neandertals (left) is a globular shape of the braincase.
(Philipp Gunz (CC BY-NC-ND 4.0))
The shape of your brain may say a lot about the Neanderthal in you. New research has shown that modern humans carrying certain genetic fragments of our closest extinct relatives, may be more elongated brain and skull than other people.
The modern man has a wealth of unique, relatively spherical skulls and brain. In contrast, the closest extinct relatives of modern humans, the Neanderthal, the elongated skulls and brains that are typical for most primates.
Previous research had suggested these contrasting skull shapes can vary in the size of the different parts of the brain in modern humans and Neanderthals, and how these areas of your brain were wired together. “However, the brain tissue does not fossilize, so that the underlying biology remained elusive,” co-lead study author Philipp Gunz, a paleoanthropologist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, told Science. [3D Images: Exploring the Human Brain]
To help solve this mystery, scientists for the first time took the CT (computed tomography) scans of seven fossil Neanderthal skull and the 19 modern human skulls. She developed the inscription of the interior of the skulls’ braincases and measured their roundness.
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In addition, the researchers analyzed nearly 4,500 of the modern man for whom they are both genetic data and magnetic resonance imaging (MRI) scans of their brains.
“We reasoned that if we could identify specific Neanderthal DNA fragments in a large enough sample of living people, we would be able to test whether one of these clips push in the direction of a less globular brain shape, so we zoom in on genes that might be important for this property,” senior study author Simon Fisher, a neurogeneticist at the Max Planck Institute for Psycholinguistics in Nijmegen, the Netherlands, told Science.
Earlier work found that modern humans and Neanderthals experienced several episodes of crosses, the introduction of Neanderthal DNA in the modern human genome. In the new study, scientists have discovered that the Neanderthal DNA fragments in the modern human chromosomes 1 and 18 were associated with less around the brain.
“The effects of the implementation of this rare Neanderthal fragments in a subtle way,” Fisher said. “The effects of the Neanderthal gene variants are small, you might not be able to see them in the shape of the cup when you meet them.”
The Neanderthal DNA fragments contain two genes that previous research linked to the development of the brain. A, UBR4, is connected with the generation of the neurons, and the other, PHLPP1 is associated with the development of fatty insulation around the nerve cells.
The researchers have discovered that this Neanderthal DNA had the strongest effects on the brain structures known as the putamen and the cerebellum — both of which are key to the preparation, learning and coordination of movements. The putamen forms the outer portion of the brain, the basal ganglia, which are associated with memory, attention, planning, learning skills and potential of speech and language.
The scientists pointed out that when a person is more Neanderthal DNA than the average, that does not necessarily mean that their brain is more elongated. “Two people who have very similar total amount of Neanderthal DNA, for example, 1 percent of their genomes — run completely different fragments,” Fisher said.
The researchers have also found that this skull differences probably do not reflect any differences in the time a baby is born: the Modern man and the Neanderthals have similar braincase and the skull shapes at that moment, Gunz said. After the birth, the differences in the development of the brain probably resulted in the pronounced differences that are found in the skull shape between adults of both sexes, he added.
Future research may look for more Neanderthal DNA are linked with the modern human brain and determine what the specific effects of these ancient genetic variants can have by the growing brain tissue with Neanderthal DNA in the laboratory, Fisher said.
The scientists detailed their findings online Dec. 13 in the journal Current Biology.
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Originally published on Live Science.