PDA

View Full Version : Neanderthal Genes and the Modern Brain



Jovialis
26-07-17, 17:19
https://www.nature.com/articles/s41598-017-06587-0

Before their disappearance from the fossil record approximately 40,000 years ago, Neanderthals, the ancient hominin lineage most closely related to modern humans, interbred with ancestors of present-day humans. The legacy of this gene flow persists through Neanderthal-derived variants that survive in modern human DNA; however, the neural implications of this inheritance are uncertain. Here, using MRI in a large cohort of healthy individuals of European-descent, we show that the amount of Neanderthal-originating polymorphism carried in living humans is related to cranial and brain morphology. First, as a validation of our approach, we demonstrate that a greater load of Neanderthal-derived genetic variants (higher “NeanderScore”) is associated with skull shapes resembling those of known Neanderthal cranial remains, particularly in occipital and parietal bones. Next, we demonstrate convergent NeanderScore-related findings in the brain (measured by gray- and white-matter volume, sulcal depth, and gyrification index) that localize to the visual cortex and intraparietal sulcus. This work provides insights into ancestral human neurobiology and suggests that Neanderthal-derived genetic variation is neurologically functional in the contemporary population.

...

Because cranial morphology is a pivotal physical element distinguishing Neanderthals from other human lineages in fossil records, it provides an ideal phenotype to test our approach and the impact of our Neanderthal-derived genetic characteristics. We anticipated that some of the Neanderthal genetic variants responsible for skull development might be represented in our sample and, when sufficiently aggregated in higher NeanderScore individuals, that these variants would be associated with hallmark Neanderthal-like morphological biases, such as increased skull length10 (https://www.nature.com/articles/s41598-017-06587-0#ref-CR10), 11 (https://www.nature.com/articles/s41598-017-06587-0#ref-CR11) and posterolateral broadening of the cranium2 (https://www.nature.com/articles/s41598-017-06587-0#ref-CR2).

...

As the distinctive cranial morphology of H. neanderthalensis is hypothesized to reflect underlying brain anatomy12 (https://www.nature.com/articles/s41598-017-06587-0#ref-CR12),13 (https://www.nature.com/articles/s41598-017-06587-0#ref-CR13),14 (https://www.nature.com/articles/s41598-017-06587-0#ref-CR14),15 (https://www.nature.com/articles/s41598-017-06587-0#ref-CR15),16 (https://www.nature.com/articles/s41598-017-06587-0#ref-CR16)



http://i.imgur.com/3L2zHqM.png
http://i.imgur.com/QHAuKKQ.png
http://i.imgur.com/9jaRibl.png



Neanderthal genes have big implications for the development of the cranium and brain. Particularly the area of the brain associated with the primary visual cortex. It is shown that this admixture has resulted in the contraction of the front of the skull near the forehead, and an expansion of the back of it.