Fossil skulls reveal how primate vision shaped the brain

Scientists published fossil evidence in Science supporting the idea that the neocortex (the outermost layer of the brain, responsible for higher cognition) evolved in a modular fashion in primates, with a disproportionately large contribution from the visual system. They analyzed endocranial casts from extinct primate species and compared them to living relatives.

The primate neocortex is larger than in related mammals, but it does not grow uniformly. The researchers show that visual regions expanded faster than other brain areas during primate evolution. This pattern is visible in early primates from tens of millions of years ago and supports the hypothesis that sharp color vision was a key driver of the striking brain size increase seen across the primate lineage.

More than evolutionary history

This is fundamental research, but it connects to a question relevant to longevity science: how is the human neocortex organized, and what makes it vulnerable or resilient in aging? If the neocortex developed in a modular way, with relatively independent regions, it follows that aging may also affect different regions at different rates. Visual areas, so prominently expanded in primates, are precisely the areas that can fail in age-related eye and brain disease.

The study also contextualizes why conditions like dementia so strongly impair spatial perception and visual processing: those functions sit in regions that underwent the most dramatic evolutionary expansion in humans.

Where does this lead?

For now, this is evolutionary neuroscience without direct clinical application. But it refines our understanding of how the human neocortex is organized, which over time can contribute to identifying which regions are most susceptible to neurodegeneration in older adults.

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