Autism’s Evolution: How Human Brain Development May Be Linked

Autism‘s Roots in Human Evolution: 10 Key Takeaways

Here are 10 key takeaways from the News Medical article about the evolutionary link to Autism spectrum Disorder (ASD):

1. Rising Prevalence: ASD affects approximately 1 in 31 children in the US and around 1 in 100 globally, suggesting a significant prevalence.
2. Uniquely Human: Autism and schizophrenia appear to be largely unique to humans, rarely observed in non-human primates, likely due to the cognitive complexity involved.
3. Brain Cell Diversity: Advances in single-cell RNA sequencing reveal a surprisingly vast array of neuronal cell types within the mammalian brain.
4. Human-Specific Genetic Changes: Large-scale sequencing studies have identified substantial genetic changes in the human brain that haven’t occurred significantly in other mammals.
5. Rapid Neuron Evolution: specifically, L2/3 IT neurons – a common type of outer-layer brain neuron – evolved exceptionally quickly in humans compared to other apes.
6. Autism Gene Link: This accelerated neuron evolution coincided with dramatic changes in genes associated with Autism Spectrum Disorder.
7. Natural selection at Play: Researchers beleive natural selection likely drove these changes in autism-associated genes within the human lineage.
8. Developmental Delay Hypothesis: A leading theory suggests these genes may be linked to developmental delay, contributing to the slower postnatal brain growth seen in humans.
9. Language Capacity Connection: The capacity for complex speech and comprehension, unique to humans, is frequently enough impacted by both autism and schizophrenia, hinting at a shared evolutionary pathway.
10. Neurodiversity as a result: As stated by lead author Alexander L. Starr, the research suggests that the very genetic changes that made the human brain unique also contributed to increased neurodiversity, including a higher prevalence of ASD.