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.
Who has a "round head"? Not me.
Really? That's so condescending.
It’s pretty simple. Skull size and shape is constrained by the birth canal. Once freed from the confines of the womb, the skull can grow and change shape to accommodate brain growth. Brainiacs end up looking like eggheads.
Exactly. Vaginal birth babies are cone heads, then the head rounds and the plates fuse.
C-section babies have round heads.
NOT SCIENCE: “Cradle a newborn and you’ll see that infants start life with elongated skulls, somewhat like Neanderthals”
If you took solid geometry and understood rather than just memorized theorems (dig at girls) you would know that a sphere is the largest volume with the smallest surface area.
Therefore a round head (no references to Cromwell and the English revolution please) is the most efficient large brain container
Unfortunately, modern skull design made it easier to put our heads up our asses...
This one should be good...
Thanks ETL, but this looks like more "why were Neandertals speechless" crap. At least the FACT that most people alive today still carry Neandertal DNA has started to seep into the barely functioning cerebral cortex of some of the jokers who kept asking for years the illogical "why did N go extinct?"
KEYWORDS: neandertal; neandertals; neanderthal; neanderthals
The Neandertal Enigma"Frayer's own reading of the record reveals a number of overlooked traits that clearly and specifically link the Neandertals to the Cro-Magnons. One such trait is the shape of the opening of the nerve canal in the lower jaw, a spot where dentists often give a pain-blocking injection. In many Neandertal, the upper portion of the opening is covered by a broad bony ridge, a curious feature also carried by a significant number of Cro-Magnons. But none of the alleged 'ancestors of us all' fossils from Africa have it, and it is extremely rare in modern people outside Europe." [pp 126-127]
by James Shreeve
in local libraries
So their hats fit, of course................
Damn, shoulda known .. lol !
EASY ANSWER.
Hats are round.
Sheesh. Hit me with a hard question.
EASY ANSWER.
Hats are round.
Sheesh. Hit me with a hard question.
This is consistent with earlier theories suggesting that Neanderthal brain growth stopped in relatively early childhood (as in apes, though not quite as extreme) while our brains continue to develop into our teens and beyond. This would mean that Neanderthal brains may have been large, but didn’t have the high neuron density or connectivity that we do - the main reason they lost and we won.
“Thanks ETL, but this looks like more “why were Neandertals speechless” crap.”
Is that an accepted fact because I would be really interested in how they determined that?
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