The interplay of two genes illuminates how the large human brain evolved

Researchers from the German Primate Center—Leibniz Institute for Primate Research and the Max Planck Institute of Molecular Cell Biology and Genetics have discovered two specific genes that evolve exclusively in humans jointly influence the development of the cerebrum. They have thus provided evidence that these genes contribute together to the evolutionary enlargement of the brain.

The work has been published in Science Advances.

The results show that the two genes act in a finely tuned interplay: one ensures that the progenitor cells of the brain multiply more, while the other causes these cells to transform into a different type of progenitor cell—the cells that later form the nerve cells of the brain. In the course of evolution, this interplay has led to the human brain being unique in its size and complexity.

The newly gained insights not only provide a deeper understanding of the evolutionary development of our brain but could also help to better comprehend how certain developmental disorders or diseases of the brain arise.

“Our findings deepen the fundamental understanding of brain development and provide new insights into the evolutionary origins of our large brain. In the long term, they could contribute to the development of therapeutic approaches for malformations of the brain,” says Nesil Eşiyok, first author of the study.

Various methods were combined for the study. In addition to animal experiments with mice, alternative methods such as chimpanzee brain organoids were also used.

“The remarkable feature of our study is that the results from animal experiments and alternative methods complement each other well and mutually confirm their findings. This not only emphasizes the high significance of our results, but could also help to reduce the need for animal experiments in the future by further developing, refining and confirming alternative methods,” explains Michael Heide, the study’s senior researcher.