Scientists may have found the gene responsible for the evolution of ape into man. German researchers found that injecting the gene into mice causes their brains to grow but also give them distinctive folds normally only found in primates.
The discovery was made by scientists at the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden, Germany, as they were comparing aborted human fetal tissue and embryonic mice. When they injected the ARHGAP11B gene into developing mice, the number of cortex stem cells nearly doubled in the animals, and their brains sometimes developed folds.
The result "emphasizes the likelihood that this gene was indeed important during mammalian evolution for the design of a new brain, bigger and more complex," Borrell Franco, a neurobiologist at the Institute of Neurosciences in Alicante, told Science Magazine.
"We specifically wanted to figure out which genes are active during the development of the cortex, the part of the brain that is greatly expanded in humans and other primates compared to rodents," said Marta Florio, a graduate student who was the principal researcher in the study. Of the 56 genes contained in the human tissue but lacking in the rodents, they found that the ARHGAP11B was the most active in dividing human stem cells.
This particular gene is well-known to experts in the area as it is found in humans and our Neanderthal and Denisovan ancestors, but not in other primates. It is believed that the gene arose from an incomplete duplication which occurred after the human and chimp lineages split off from one another. "That it was a human-specific gene duplication made it very exciting," said Wieland Huttner, a senior neurobiologist at the German institue.
The scientists admit that there were likely other genes involved in the development of the human cortex but this discovery is no doubt a major milestone that will help us understand how the human brain came about. Read the full report here.
Photo: Taymaz Valley | Flickr
