Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news of exciting discoveries, scientific breakthroughs and more.
CNN
—
By studying fossilized skulls, scientists know that Neanderthal brains were about the same size, if not slightly larger, than modern humans. However, researchers know very little about Neanderthal brain development because soft tissue is not well preserved in the fossil record.
A fascinating study published on September 8 has revealed a potential difference that may have given modern humans, or Homo sapiens, a cognitive advantage over Neanderthals, the Stone Age hominins who lived in Europe and parts of Asia before they went extinct about 40,000 years ago. .
Scientists at the Max Planck Institute for Molecular Cell Biology and Genetics in Dresden, Germany, said that they discovered a genetic mutation in the brain of Homo sapiens that causes faster generation of neurons. The Neanderthal variant of the gene in question, known as TKTL1, differs from the modern human version 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 two versions of the gene were inserted into mouse embryos, the research team found that the modern human version of the gene resulted in an increase in a special type of… cell that makes neurons in the neocortex region of the brain. The scientists also tested the two gene variants in ferret embryos and lab-grown brain tissue made from human stem cells, called organoids, and found similar results.
According to the study, published in the journal Science, the team reasoned that the ability to produce more neurons gave Homo sapiens a cognitive advantage unrelated to overall brain size, suggesting that modern humans have “more neocortex to work with than ancient Neanderthals.” drove. .
“This shows us that although we don’t know how many neurons the Neanderthal brain had, we can assume that modern humans have more neurons than Neanderthals in the frontal part of the brain where TKTL1 activity is highest,” Huttner said.
“It has been debated whether the frontal lobe of Neanderthals was as large as that of modern humans,” he said.
“But we don’t need to worry because (from this study) we know that modern humans need more neurons in the frontal lobe… and we think that’s an advantage for their cognitive abilities.”
Alysson Muotri, professor and director of the Stem Cell Program and Archaealization Center at the University of California, San Diego, said that while animal experiments have revealed a “pretty dramatic difference” in neuron production, the difference is more subtle in organelles. He was not involved in the study.
“This was done in only one cell line, and since we have great variability with this brain organelle protocol, it would be ideal to repeat the experiments with a second cell line,” he said via email.
Muotri noted that the archaic version of the TKTL1 gene was also not unique to Neanderthals. Most genomic databases focus on Western Europeans, and human populations in other parts of the world may share a Neanderthal version of this gene.
“I think it is too early to draw differences between Neanderthal and modern human cognition.
Archaeological findings in recent years suggest that Neanderthals were more complex than pop-culture depictions of savage cavemen. Our ancient relatives knew how to survive in cold and hot climates and used sophisticated tools. They too made yarnswam and created art.
Study co-author and geneticist Svante Pääbo, director of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, led the effort to extract, sequence and analyze ancient DNA from Neanderthal bones.
His work led to the discovery In 2010, the first humans interbred with Neanderthals. The scientists then compared the Neanderthal genome to the genetic record of living humans today to see how our genes overlapped and differed: TKTL1 is just one of dozens of genetic differences identified. some shared genes may have implications for human health.
