Posted on 12/13/2018 8:50:37 AM PST by ETL
Ever since researchers first got a good look at a Neanderthal skull in the 1860s, they were struck by its strange shape: stretched from front to back like a football rather than round like a basketball, as in living people. But why our heads and those of our ice age cousins looked different remained a mystery.
Now, researchers have found an ingenious way to identify genes that help explain the contrast. By analyzing traces of Neanderthal DNA that linger in Europeans from their ancestors' trysts, researchers have identified two Neanderthal gene variants linked to slightly less globular head shape in living people, the team reports this week in Current Biology. The genes also influence brain organization, offering a clue to how evolution acting on the brain might have reshaped the skull. This "very important study" pinpoints genes that have a "direct effect on brain shape and, presumably, brain function in humans today," says paleoanthropologist Chris Stringer of the Natural History Museum in London, who was not a part of the work.
Cradle a newborn and you'll see that infants start life with elongated skulls, somewhat like Neanderthals. It's only when the modern human brain nearly doubles in size in the first year of life that the skull becomes globular, says paleoanthropologist Philipp Gunz of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. He and his colleagues analyzed computerized tomography scans of modern human and Neanderthal skulls to develop a "globularity index" of human brains.
To explore the underlying differences in brain tissue, they applied that index to MRI scans from 4468 people of European ancestry whose DNA had been genotyped. The team identified two Neanderthal DNA fragments that were correlated with slightly less globular heads. These DNA fragments affect the expression of two genes: UBR4, which regulates the development of neurons, and PHLPP1, which affects the development of myelin sheaths that insulate axons, or projections of neurons.
The Neanderthal variants may lower URB4 expression in the basal ganglia and also lead to less myelination of axons in the cerebellum, a structure at the back of the brain. This could contribute to subtle differences in neuronal connectivity and how the cerebellum regulates motor skills and speech, says senior author Simon Fisher of the Max Planck Institute for Psycholinguistics in Nijmegen, the Netherlands. But any effects of the Neanderthal genes in living people would be slight because so many genes shape the brain.
Tying Neanderthal DNA to brain scans in living people is an "innovative and exciting approach" because "soft tissue in the brain is impossible to access from the fossil record," says anthropologist Katerina Harvati of the University of Tübingen in Germany. She'd like to see the findings confirmed in more people.
Indeed, Gunz and Fisher plan to delve into the UK Biobank, a giant database of British people's health records and DNA. They hope to use Biobank brain scans to find more genes and to explore how Neanderthal brains would have functioned. "The Neanderthal DNA that remains in us can help us think about what their brains were like," says geneticist Tony Capra of Vanderbilt University in Nashville.
Scans of skulls show modern human infants start out with elongated heads—somewhat like Neanderthals—but they round out in adulthood.
There's a Red Hat over yonder, that's where my baby codes...
My guess: Moms of babies with smaller heads better survived birth and lived on to have more smaller headed fertile offspring.
It's hard to prove a negative here since speech doesn't fossilize, but a similar question might be "Why were Neanderthals less capable of technological and cultural innovation than humans" - they used the same crude stone tools for their entire 400 thousand year history (except what they got from exchanges with humans towards the end of their history), while we kept on innovating. We were smart and versatile enough to change our mode of life when the climate, plants, and animals changed all around us at the end of the Ice Age, they weren't and couldn't compete. Now we have evidence from skulls and genes to help explain why.
The irony is that Lucy was always calling him a “Blockhead”.
Try passing a Neanderthal through the birth canal. It’s no wonder they died out.
Yeah, but you should see Neanderthal hips!
"Road House!"
Question to which you or someone else here may or may not have the answer. Where are the sutures of the skull on the Neanderthal? We know the skull keeps growing, so could the skull on the right represent a very old individual?
Re pic: I assume the one on the right is the Neanderthal. His is bigger.
Sorry, I don’t know, and don’t have time now to research it.
But here’s something I found on a quick search that might include an answer, or at least have additional info...
Neanderthal skulls and brains may have developed just like ours
25 July 2016
I assume the one on the right is the Neanderthal.
Of course. Look at the sloping forehead and elongated skull.
Thank you.
“Therefore a round head (no references to Cromwell and the English revolution please) is the most efficient large brain container”
Or maybe for temperature control or resistance to fracture, or all of the above. On the other hand, the cerebral cortex wrinkles up, apparently to maximize surface/volume. It’s akin to a 3D fractal surface.
Much larger trapezius muscles?
Because there ain’t NO way in hell a sane woman would consent to give birth to a square headed youngun?
‘stretched from front to back like a football”
Neanderthals invented football coz they wanted to get ahead in the game-\
Remember the good-ol` NFL? Neanderthal football League
and their first and last Stupor Bowl?-
They played against the CFL [Cro-Magnon Football League] but lost in sudden death overtime when a CFL kicker
mistakenly kicked a Neanderthal`s head, splitting the uprights and the head simultaneously... The kick was good.
Some various tribes worldwide, wrapped their infants heads in order to get elongated or flattened shapes. Anyone have any pics skills of that sort?
Remember, no culture is "better", or more advanced, than any other. Just different.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.