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By studying fossilized skulls, scientists know that the brain size of a Neanderthal man was the same, if not slightly larger, than that of a modern human. However, researchers know little about Neanderthal brain development because soft tissues do not preserve well in the fossil record.
Now, an intriguing study published on September 8 has revealed a potential difference that could have given modern humans, or Homo sapiens, a cognitive advantage over Neanderthals, Stone Age hominids that lived in Europe and parts of Asia before going extinct about 40,000 years ago. .
Scientists at the Max Planck Institute for Molecular Cell Biology and Genetics in Dresden, Germany, say they have identified a genetic mutation that triggered the faster creation of neurons in the brains of Homo sapiens. The Neanderthal variant of the gene in question, known as TKTL1, differs from the modern human variant by one amino acid.
“We have identified a gene that helps make us human,” said study author Wieland Huttner, professor and director emeritus of the institute.
When both versions of the gene were inserted into mouse embryos, the research team discovered that the modern human variant of the gene resulted in an increase in a specific type of… cell that creates neurons in the neocortex region of the brain. The scientists also tested the two genetic variants in ferret embryos and brain tissue grown in the lab from human stem cells, called organoids, with similar results.
The team reasoned that this ability to produce more neurons likely gave Homo sapiens a cognitive advantage unrelated to overall brain size, suggesting that modern humans have “more neocortex to work with than the ancient Neanderthal”. according to the study published in the journal Science. .
“This shows us that even though we don’t know how many neurons the Neanderthal brain had, we can assume that modern humans have more neurons in the frontal lobe of the brain, where TKTL1 activity is highest, than do modern humans. Neanderthals,” Huttner explained.
“There has been some discussion about whether or not the Neanderthals’ frontal lobe was as large as that of modern humans,” he added.
“But we don’t need to worry about that because (from this research) we know that modern humans must have more neurons in the frontal lobe…and we think that’s an advantage for abilities. cognitive.”
Alysson Muotri, professor and director of the Stem Cell Program and Archaealization Center at the University of California, San Diego, said that while the animal experiments revealed “a pretty dramatic difference” in neuron production, the difference was more subtle in the organoids. He did not participate in the research.
“This was only done in one cell line, and since we have huge variability with this brain organoid protocol, it would be ideal to repeat the experiments with a second cell line,” he said per E-mail.
It was also possible that the archaic version of the TKTL1 gene was not unique to Neanderthals, Muotri noted. Most genomic databases have focused on Western Europeans, and it is possible that human populations in other parts of the world share the Neanderthal version of this gene.
“I think it’s quite premature to suggest differences between Neanderthals and modern human cognition,” he said.
Archaeological discoveries in recent years have suggested that Neanderthals were more sophisticated than pop culture depictions of brutal cavemen suggest. Our ancient parents knew how to survive in cold and hot climates and used complex tools. They also made yarn, swam and created art.
Study co-author and geneticist Svante Pääbo, director of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, was the first to extract, sequence and analyze ancient DNA from Neanderthal bones.
His work led to the discovery in 2010 that early humans interbred with Neanderthals. The scientists then compared the Neanderthal genome with the genetic archive of humans alive today to see how our genes overlap and differ: TKTL1 is just one of dozens of identified genetic differences, while some shared genes may have implications for human health.