Neanderthals have long been portrayed as our goofy, bully cousins. Now, groundbreaking research has revealed, though not confirmed the stereotype, striking differences in the brain development of modern humans and neanderthals.
The study involved inserting a Neanderthal brain gene into mice, ferrets, and “mini-brain” structures called organoids, grown in the lab from human stem cells. The experiments revealed that the Neanderthal version of the gene was linked to slower creation of neurons in the cerebral cortex during development, which the scientists said could explain superior cognitive abilities in modern humans.
“Producing more neurons lays the groundwork for higher cognitive function,” said Wieland Huttner, who led the work at the Max-Planck Institute for the Molecular Cell. biology and Genetics. “We think this is the first convincing evidence that modern humans were cognitively better than Neanderthals.”
modern humans and neanderthals they split into separate lineages around 400,000 years ago, with our ancestors staying in Africa and the Neanderthals moving north into Europe. Around 60,000 years ago, a mass migration of modern humans out of Africa brought the two species face-to-face once again and they interbred: modern humans of non-African heritage carry 1-4% of Neanderthal DNA. However, 30,000 years ago, our ancient cousins had disappeared as a distinct species and the question of how we surpassed the Neanderthals remains a mystery.
“One hard fact is that wherever homo sapiens went, they would basically outcompete other species there. It’s a bit weird,” said Professor Laurent Nguyen of the University of Liège, who was not involved in the latest research. “These guys [Neanderthals] they were in Europe long before us and would have adapted to their environment, including pathogens. The big question is why we would be able to overcome them.”
Some argue that our ancestors had an intellectual edge, but until recently there has been no way to scientifically test the hypothesis. This changed in the last decade when scientists successfully sequenced neanderthal dna of a fossilized finger found in a Siberian cave, paving the way for new insights into how Neanderthal biology differs from our own.
The latest experiments focus on a gene, called TKTL1, involved in neuronal production in the developing brain. The Neanderthal version of the gene differs by one letter from the human version. When inserted into mice, the scientists found that the Neanderthal variant led to the production of fewer neurons, particularly in the brain’s frontal lobe, where most cognitive functions reside. The scientists also tested the gene’s influence on ferrets and spots of lab-grown tissue, called organoids, which replicate the basic structures of the developing brain.
“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 in the frontal lobe of the brain, where [the gene’s] activity is higher than that of Neanderthals,” said Anneline Pinson, first author of the study.
Chris Stringer, head of human origins research at the Natural History Museum in London, described the work as “pioneering” and said it began to address one of the central puzzles of human evolution: why, with all the past diversity, of humans, we are now the only ones left.
“Ideas have come and gone: better tools, better weapons, proper language, art and symbolism, better brains,” Stringer said. “At long last, this provides a clue as to why our brains might have surpassed those of Neanderthals.”
More neurons does not automatically equate to a more intelligent type of human being, although it does dictate the brain’s basic computing ability. Human brains contain about twice as many neurons as the brains of chimpanzees and bonobos.
Nguyen said the latest work is far from definitive proof of modern humans’ superior intellect, but it does show that Neanderthals had significant differences in brain development. “This is an exciting story,” she added.
