Let’s help solve the debate presented in this quoted tweet…
I.
The genetic evidence surrounding Neanderthals provides a compelling case against the standard evolutionary narrative of human origins. Modern humans and Neanderthals share approximately 99.7% of their DNA sequence, a level of similarity far greater than the roughly 98–99% often cited between humans and chimpanzees…yet no one classifies chimpanzees as a mere variant of humanity. This near-identity indicates that Neanderthals were not some distant, transitional “ape-man” species on an evolutionary ladder, but rather fully human populations exhibiting natural variation within the same created kind.
As mentioned in the quoted post a striking skeletal distinction further illustrates this point…unlike Neanderthals, whose mandibles lack a protruding chin (a receding or sloping symphysis), Homo sapiens uniquely possesses a prominent, forward-projecting chin…a bony mental eminence that emerges during postnatal development. This feature is absent not only in Neanderthals but in all other known hominins and primates, making it a true autapomorphy of modern humans. Evolutionary explanations for the chin often reduce it to a byproduct of facial gracilization (smaller, flatter faces due to reduced prognathism), changes in bone remodeling patterns during ontogeny, or incidental geometric outcomes from shrinking jaws…yet these accounts struggle to identify a clear selective advantage, underscoring how arbitrary such “just-so” stories can be.
The discovery of interbreeding further undermines evolutionary predictions. Non-African populations today carry 1–4% Neanderthal-derived DNA (with traces in some African groups from later migrations), resulting from gene flow that occurred after modern humans dispersed from their point of origin. Evolutionary models initially anticipated that Neanderthals represented a separate lineage too divergent for successful reproduction with Homo sapiens, yet genomic data revealed fertile interbreeding and even adaptive benefits from certain introgressed alleles (e.g., immune-related genes). Rather than supporting gradual divergence over hundreds of thousands of years, this pattern aligns more readily with a recent, shared ancestry followed by rapid post-dispersal diversification…consistent with a historical model of human unity descending from a common source, with subsequent regional adaptations.
Physical traits once labeled “primitive” in Neanderthals…such as robust skeletal structure, prominent brow ridges, larger nasal cavities, and forward-projecting midfaces…have been reevaluated in light of developmental biology, pathology, environmental influences, and even potential effects of longevity or nutritional factors in some specimens. Archaeological evidence demonstrates Neanderthal behavioral modernity…ritual burial, complex tool manufacture, symbolic art, and social organization indistinguishable in kind from early modern humans. These are hallmarks of fully human cognition, not evolutionary intermediates.
*conclusion in first comment
Biologists have debated the reason why Homo sapiens evolved a prominent lower jaw, but this unique feature may actually be a by-product of other traits shaped by natural selection
newscientist.com/article/251…