"But now US researchers say that natural selection could have given rise to autism-associated genes, with behaviours associated with the disorder generally involving cognitive traits that are unique to humans. Writing in the journal Molecular Biology and Evolution, experts at Stanford University discovered that the most abundant type of outer-layer brain neurons-called L2/3 IT neurons-evolved exceptionally quickly in humans compared to other mammals."
"This rapid evolution involved a marked downregulation in genes linked with autism and schizophrenia, supporting the hypothesis that lower expression of autism-linked genes in humans increases the risk of autism. According to the researchers, this accelerated evolution saw dramatic changes in autism-associated genes, which was likely driven by natural selection-a mechanism of evolution by which a species changes over time in response to changes in the environment, or competition between organisms."
Autism and other neurodevelopmental disorder diagnoses have increased for decades, with prevalence estimates around one in 36 children in the UK and about one in 100 globally. Multiple explanations exist for rising rates, including diagnostic changes, greater awareness, and proposed environmental factors such as prenatal medication exposure. Rapid evolutionary change in human outer-layer cortical neurons, specifically L2/3 IT neurons, involved downregulation of genes linked to autism and schizophrenia. Lower expression of autism-associated genes in humans may increase autism risk. The accelerated genetic changes were likely driven by natural selection, and one possible benefit was prolonged postnatal brain development supporting language and complex cognition.
Read at Mail Online
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