Recent research comparing the visual processing system of the gray mouse lemur with that of much larger and more recently evolved primates including humans suggests that, once the visual cortex of very early primates settled into a highly functional design, it didn’t evolve much further.
Publishing in the February 2021 issue of Current Biology, scientists at the University of Geneva, the Max Planck Institute in Göttingen, and the National Museum of Natural History in Paris propose that, for modern primates of any size, the fundamental units of the visual cortex may be nearly identical in function, design, and size to those of the gray mouse lemur.
According to [researcher Daniel] Huber, fifty-five million years of stability is extraordinary in a complex biological system that serves so many different species.
The gray mouse lemur was declared a threatened species in 1975, though now the International Union for Conservation of Nature Red List of Threatened Species numbers it among those of the Least Concern… Considering how closely today’s gray mouse lemurs resemble the fossils of the very earliest primates, if the entire species disappears one day, so will a treasure chest of information about human vision, and even about humans in general.