A new scientific study has revealed that hundreds of genes in the human brain work differently in males and females, reinforcing the idea that genetic differences, and not just hormonal or environmental ones, play a fundamental role in shaping behavior and neural functions, and possibly in susceptibility to brain diseases like Alzheimer's and Parkinson's. The study, conducted by Professor Jenny Graves from 'La Trobe University' in Australia and published on the ScienceAlert science website, explained that the genetic differences in the brain appear from the earliest stages of embryonic development. Researchers examined brain tissues from human embryos after death and found that over 1,800 genes were more active in male embryos, compared to 1,300 genes more active in females. These patterns later match what is observed in adult brains. Transcriptome analysis, which is a record of gene activity in cells, also showed that about 610 genes are more active in male brains, versus 316 genes in female brains. Notably, these differences are not limited to genes on the sex chromosomes 'X' and 'Y'; about 90% of the sex-biased genes are located on the regular chromosomes shared by both sexes, suggesting the existence of hidden regulatory mechanisms, with hormones like 'testosterone' and 'estrogen' likely being among the factors. The study did not stop at humans; it found similar patterns of gene activity in the brains of monkeys, mice, and even worms, indicating that these variations are ancient and date back to a common ancestor more than 70 million years ago. Graves stated that it is too early to conclude that these genetic differences mean a difference in intelligence, thinking, or cognitive abilities between the sexes, but she confirms that differences in gene expression of this magnitude must affect some neural functions.
