Prepare to have your mind blown! A groundbreaking study, yet to be peer-reviewed, challenges the existing explanations for the incredible size of our brains. Mauricio González-Forero from the University of St Andrews reveals that the commonly accepted theory of an evolutionary arms race falls short in explaining the precise dimensions of our impressive brainpower. According to González-Forero, “the arms races fail to yield evolutionarily stable human-sized brains and bodies given their metabolic costs.”
In simpler terms, growing a brain comes at a cost and limits the energy available for the development of other tissues. Under the arms race scenario, it would have been impossible for us to have both a large brain and such magnificent bodies.
But fear not! González-Forero has come to the rescue with a mind-boggling computer model that combines evolutionary and developmental dynamics. This “evo-devo dynamics framework” accurately reconstructs the brain and body sizes of seven different hominid species.
Starting with Australopithecus afarensis, the species to which the famous Lucy belongs, and continuing all the way to Homo sapiens, González-Forero unveils a fascinating correlation. Brain size is always dependent on the age of sexual maturation. In other words, as the age of sexual development increases, so does the size of the brain.
Let’s take modern humans as an example. González-Forero demonstrates that the relatively late onset of ovarian follicles in females allows for a mind-blowing expansion in brain size during childhood. As a result, our adult human brains are six times larger than what would typically be expected for our body size.
But here’s the mind-blowing twist: our colossal brains are not the result of an evolutionary arms race to become smarter. They are actually a byproduct of our delayed sexual development. González-Forero’s model reveals that the expansion of our brains is due to direct selection on follicle count, rather than brain size.
Prepare to have your beliefs challenged! This groundbreaking study, currently available as a preprint on BioRxiv, will revolutionize our understanding of the human brain.
