Researchers from the Hebrew University have developed an innovative method to reconstruct DNA methylation patterns from ancient humans, which offers explanations for the evolutionary processes that led to the growth and complexity of the human brain.
A new study conducted at the Hebrew University of Jerusalem presents an innovative method for inferring DNA methylation patterns in tissues that did not come from ancient skeletons, and provides a deeper understanding of the evolutionary processes that shaped the human brain and neural functions. The findings may change the way we study the evolution of complex human traits.
Over the course of about two million years, a short time in evolutionary terms, the human brain tripled in size. This rapid development is probably what allowed us to develop complex mental abilities such as language, or developed inventiveness. Many researchers are trying to understand the basis of the phenomenon, among other things by comparing the DNA of modern humans, ancient humans and chimpanzees.
In recent years, there has been a growing understanding that not only the genetic sequence is significant for evolutionary processes, but also epigenetics, the control of the genes, which varies between different species and between different individuals, thus creating differences between them. But to learn about epigenetic processes in the brain, it is necessary to find brain tissue. To this day, not a single brain remains of ancient humans, such as the Neanderthal man, have been preserved, and today most research in the field focuses on bones, because the rest of the tissues are hardly preserved over the years.
A new study led by doctoral student Yoav Me Tov, under the direction of Prof. Liran Carmel and Prof. Eran Mashor from the Department of Genetics and the Edmond and Lili Safra Center for Brain Research (ELSC) at the Hebrew University, allows a glimpse into the minds of ancient humans for the first time. The researchers developed an algorithm that makes it possible to reproduce the patterns of DNA methylation, a key epigenetic index, from organs other than bones, and managed to achieve an accuracy of up to 92% in prediction.
The team applied the algorithm to ancient humans, and revealed over 1,850 sites where there were epigenetic changes in the brain, some between modern humans and other ancient human groups, and some between humans in general and the chimpanzee. Many of these sites are located within genes with a central function in brain development, including genes linked to intelligence and cognitive abilities. Intriguingly, changes were also found on genes from the NBPF family, which are linked to key processes in the evolution of the human brain such as the astronomical increase in brain volume, the development of mental abilities and even brain disorders such as autism and schizophrenia.
"Our method allowed us to look for the first time at epigenetic changes in the brain, even in samples from ancient humans," says Mah-Tov, "but now it can be used to understand evolutionary processes that also occur in other tissues that do not usually survive. In terms of the potential for new discoveries, the sky is the limit." .
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One response
The title of the article is incorrect. The article explains processes of change in the brain, but does not explain at all why the brain is the size it is.