Autism's Evolutionary Roots Uncovered: Unique Human Brain Adaptations Identified

According to a study published in September 2025, scientists have uncovered evidence that autism may be linked to the unique evolutionary adaptations of the human brain. The lead author, Alexander L. Starr, explains that "some of the same genetic changes that make the human brain unique also made humans more neurodiverse."

The research reveals that the most common type of outer-layer neurons, known as L2/3 IT neurons, underwent especially rapid evolution in humans compared to other apes. Strikingly, this fast-paced shift coincided with major alterations in genes associated with autism. While the exact evolutionary benefit remains uncertain, the team suggests these genetic changes may have played a role in the slower pace of postnatal brain growth in humans versus chimpanzees.

One possibility is that the evolution of autism-related genes extended the time window for learning and complex thought in childhood, offering an advantage by fostering more advanced reasoning skills. The unique human capacity for speech and language, often impacted by autism and schizophrenia, may also be connected to these adaptations.

Overall, the findings strongly indicate that evolutionary pressures have shaped the genetic underpinnings of autism, shedding new light on this complex neurological condition that affects an estimated 3.2% of children in the United States.