Abstract
Aging is associated with robust decline of the brain’s gray matter. This spatially specific, morphological change in humans has recently been found in chimpanzees. Direct comparison of age-related brain deterioration between these great ape species can provide a unique evolutionary perspective on human brain aging. Here, we present a data-driven, cross-species comparative framework to explore the relationship between gray matter atrophy with age and cross-species cerebral expansion in chimpanzees and humans. In humans, we found a positive relationship between cerebral aging and cortical expansion, whereas, in chimpanzees no such relationship was found. The greater aging and expansion effects in higher-order cognitive regions like the orbito-frontal cortex were observed to be unique to humans. This resembles the last in, first out hypothesis for neurodevelopment and may represent a biological cost for recent evolutionary developments of human faculties.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
This manuscript has been revised by changing cross-species expansion to relative cross-species expansion. Therefore the scale on figure 4 and 5 changed. Additionally, some editorial changes to the text have been made.
