Single amino acid change could hold key to Neanderthal demise
19 Sep 2022
New research addresses the puzzle of why, of all the human species to have evolved, only our own avoided extinction.
Previous evidence has suggested that one of Homo Sapiens’ most advanced competitors, Neanderthals, had brains and neocortexes – responsible for congnitive function – that were comparable in size to modern humans.
In addition, they were well established in areas of Europe and showed evidence of relatively sophisticated tool manufacture.
Speculation continues as to the cause of the rival species’ demise and eventual extinction and to what degree this was due to differing cognitive ability.
The introduction to the study published in Science identifies the effect that a single amino acid change – present in the transketolase-like 1 (TKTL1) protein of modern humans but not in earlier species – exerts “on production of basal radial glia, the workhorses that generate much of the neocortex”.
This allowed the production of more neurons in the neocortex, boosting cognitive function.
Tests on mice embryos and human embryonic stem cells established evidence that hTKL1 – the modern human TKTL1 variant – was markedly more effective in producing progenitor cells that generate neurons than was archaic TKTL1, referenced as aTKTL1.
The authors conclude in the published research:
“In light of our finding that TKTL1 expression in fetal human neocortex is particularly high in the developing frontal lobe, our study implies that because of the single amino acid–based activity of hTKTL1, neocortical neurogenesis in modern humans was and is greater than it was in Neanderthals, in particular in the frontal lobe.”
