Sunday, July 21, 2024

Differences revealed in human and Neanderthal brains


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By studying fossilized skulls, scientists know that the size of the Neanderthal brain was the same, if not slightly larger, than the size of the brain of modern humans. However, researchers didn’t know much about the evolution of the Neanderthal brain because soft tissues are not well preserved in the fossil record.

Now, an interesting study released on September 8 has revealed a possible difference that may have given modern humans, or Homo sapiens, a cognitive advantage over Neanderthals, the Stone Age hominids who lived in Europe and parts of Asia before their extinction 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 led to faster formation of neurons in the brain of Homo sapiens. The primitive variant of the gene in question, known as TKTL1, differs from the modern human variant by a single amino acid.

“We have identified a gene that contributes to making us human,” said study author Weiland Hutner, professor and emeritus director at the institute.

When two copies of the gene were inserted into the embryos of mice, the research team found that a modern human variant of the gene led to an increase in a specific type of… cells that create neurons in the neocortex region of the brain. The scientists also tested the two genetic variants in rodent embryos and lab-grown brain tissue made from human stem cells, called organoids, with similar results.

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The team concluded that this ability to produce more neurons likely gave Homo sapiens a cognitive advantage unrelated to overall brain size, suggesting that modern humans had “more neocortex to work with than ancient Neanderthals,” according to the study. Published in Science magazine.

“This shows us that although we don’t know how many neurons a Neanderthal brain has, we can assume that modern humans have a higher number of neurons in the frontal lobe of the brain, where TKTL1 activity is higher than that of Neanderthals,” Huttner explained.

“There has been debate about whether the frontal lobe of Neanderthals was as large as that of modern humans,” he added.

“But we don’t need to care because (from this research) we know that modern humans should have more neurons in the frontal lobe…and we think that’s an advantage of cognitive abilities.”

Alison Muotri, professor and director of the Stem Cell Program and Archeology Center at the University of California San Diego, said that while animal experiments revealed a “completely significant difference” in neuron production, the difference was more subtle in organelles. He did not participate in the research.

“This was only done in one cell line, and since we have so much versatility with this protocol for brain organoids, it would be ideal to repeat the experiments with a second cell line,” he said via email.

It’s also possible that the ancient version of the TKTL1 gene was not unique to Neanderthals, Muotri noted. Most genomic databases have focused on Western Europeans, and humans in other parts of the world likely shared the Neanderthal version of this gene.

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“I think it’s too early to suggest differences between Neanderthals and modern human cognition,” he said.

Archaeological discoveries in recent years have indicated that Neanderthals were more complex than popular culture depictions of savage cavemen might suggest. Our ancient relatives knew how to survive in cold and warm climates and used complex tools. them too making yarnswam and art creation.

Study co-author and geneticist Svante Pääbo, director of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, pioneered efforts to extract, sequence and analyze ancient DNA from Neanderthal bones.

His work led to the discovery in 2010: The first humans intermarried with Neanderthals. Scientists later compared the Neanderthal genome with the genetic records of living humans today to see how our genes overlap and differ: TKTL1 is just one of dozens of specific genetic variations, While some common genes may have implications for human health.