Dr Mauricio Gonzalez-Forero (St Andrews): Why did the human brain size evolve? A way forward School of Psychology and Neuroscience Friday seminar series

The School of Psychology and Neuroscience seminar series presents a talk by Dr Mauricio Gonzalez-Forero of St Andrews University, titled “Why did the human brain size evolve? A way forward,” on Friday 13 September 2024, 1pm to 2pm. The seminar will be hosted by Dr Maarten Zwart in Seminar Room 1 and will also be accessible online via Teams.

Abstract:
The human brain is thought to be exceptionally adaptive. It has enabled us to control our environments and to thrive across the planet and beyond, with little indication that the human brain has exhausted its reach. The human brain's perceived adaptive nature and immense complexity have long made natural selection the only credible explanation for why it evolved. Despite this, I describe detailed modelling of human brain size development and evolution integrated with data that finds that the human brain size may not have evolved due to direct selection for it, but as a byproduct of selection for something else, specifically increased ovarian follicle numbers. In these results, ecology and seemingly cumulative culture are found to cause hominin brain expansion, yet not by increasing selection for brain size or cognition as widely believed but by generating the genetic correlation between brain size and ovarian follicles that expands the brain, a correlation supported by recent empirical evidence. These results entail the intriguing possibility that the large human brain size may be a spandrel rather than adaptation and warn against persistent practices of considering adaptiveness or directional evolution as necessarily caused by selection. I discuss how these results so far only show why the human brain size could have evolved and how building upon this approach offers a way forward to pursue the sometimes-thought unanswerable question of why the human brain size actually evolved.