Editing Openai/69177fbb-14c4-800f-bc57-ccb5a1d88c95 (section)

=== The most decisive counterpoint combines population genetics and selection patterns. ===

==== When Neanderthal DNA entered the Homo sapiens gene pool, natural selection removed most of the segments that touched: ====
* neural progenitor proliferation
* cortical development pathways
* synaptic gene networks
* language-related loci (e.g., FOXP2-adjacent regions)
* brain size and skull growth patterns

This wasn’t mild drift—it was strong negative selection, especially in high-expression brain regions. Large comparative studies show a massive underrepresentation of Neanderthal segments in exactly the regions that would need to survive if they contributed to autistic traits.

If Neanderthals carried alleles shaping “autistic-like cognition,” and those alleles were advantageous or even neutral in Homo sapiens, selection would have kept them. Instead, the opposite happened.

This is the hardest single blow to RDOS’s framework.

==== Autism risk involves hundreds of genes with small effect sizes, plus de novo mutations. Genome-wide association studies show: ====
* none of the highly replicated autism-associated loci come from introgressed Neanderthal segments
* Neanderthal-derived regions have no enrichment for ASD risk variants
* most introgressed segments influence physiology, not cognition

If Neanderthal traits were behind the autistic cognitive profile, there would be at least faint statistical signals—there are none.

==== Large genetic datasets comparing thousands of autistic and non-autistic individuals show no ancestry-level difference. Everyone with Eurasian ancestry has basically the same 1–2% Neanderthal proportion. ====

No elevation = no link at the population level.

==== Neanderthals exhibit: ====
* care for injured members
* deliberate burial practices
* symbolic behavior
* cooperative hunting
* ornamentation and pigments

This undermines the idea of them as “solitary, pattern-oriented, low-social-signal” types.

Altogether, the empirical burden is heavy and one-sided.