“There is no more exciting scientific question than discovering and decoding the mysterious genetic changes that made us who we are.”
It is believed that between our brain and that of the Neanderthals there really aren’t that many differences, although fossils have been examined, and it has not been possible to correctly recreate the form and function of our ancestors’ brains. With this in mind, Svante Pääbo and Wieland Huttner carried out a study on the ancient and modern genome, thus answering the question we have been asking for years, what made us human?
Why are we human?
Svante Pääbo and Wieland Huttner, experts in the study and sequencing of ancestral human genomes, as well as embryonic brain development and its unique aspects in humans, examined the Neanderthal genome. In their research, they found that modern humans differ from apes and Neanderthals only by an amino acid change in TKTL 1, a type of protein abundant in the cerebral cortex, especially in the frontal lobe.
To study the consequences of this difference in the development of the embryonic cerebral cortex, Pääbo and Huttner overexpressed the modern and ancient TKTL 1 genome. They found that the modern genome increased the abundance of bRG cells, in contrast to the ancient genome. This cell type is a cortical progenitor with a high capacity to produce cortical neurons.
Researchers have proposed a mechanism that would make this small change in the cortex have a significant impact. According to the results, the amino acid change leads to a considerable modification of the size and pattern of the cortical folds, which are believed to be the ones that most separate us from apes. This gene is the answer to the age-old question of why we are human.
“Our brains tripled in size through the expansion of certain functional areas of the cerebral cortex, and that has to be a fundamental substrate for us to become human,” said David Haussler, a bioinformatician at the University of California, who co-led the study. “There is no more exciting scientific question than discovering and decoding the mysterious genetic changes that made us who we are,” he said.
However, despite Pääbo and Huttner’s research, many scientists have been skeptical. Many of them share the idea that the brain is a complex organ and its cognitive process is even more so, they also argue that its evolution depends on different environmental factors, and they consider that reaching these conclusions using a single gene in cell culture or expression experiment is reductionist.
Despite the comments the study has received, it signifies the beginning of genetic research that could shed more light on the evolution of human beings and finally discover what led us to our current configuration.
Story originally published in Spanish in Ecoosfera