The hippocampus is a region of the brain involved in the consolidation of memory and spatial navigation. But whilst our brains have grown more than 3-fold over the course of human evolution the hippocampus has experienced much less change, only increasing in size by 1/3 or so. Most of the increase in our brain occurred in the neocortex. But might this soon change?
Researchers in China have identified a SNP of SEMA5A – a gene involved in the production of proteins used in the creation and maintenance of neurons – that seems to be correlated with a larger hippocampus. This change to a single base pair resulted in a ~5% increase in hippocampal volume (although curiously, only in the right hemisphere of the hippocampus).
Given the role of the hippocampus in spatial reasoning, these researchers did a follow-up in which they tested this ability in participants. As one might expect, they found that those with this variant of SEMA5A (and thus larger hippocampuses/hippocampi/whatever, silly latin) performed better than those with regular, puny hippocampuses.
As such there’s a real advantage to having this variant, which natural selection might work on and in a few thousand generation we might all have slightly improved brains. Of course, this is assuming that this improvement in spatial reasoning correlates with an improvement with reproductive success. Maybe one day GPS systems will fail, and reading a map will become the sexiest thing ever.
Zhu, B., Chen, C., Xue, G., Moyzis, R. K., Dong, Q., Chen, C., … & Lin, C. (2013). The SEMA5A gene is associated with hippocampal volume, and their interaction is associated with performance on Raven’s Progressive Matrices. NeuroImage.