What are the chances that we discover that in some ways they were more advanced than early homo sapiens (I'm not saying "us" here, as I have a lot of Neanderthal DNA)?
100% they were more advanced than early homosapiens. In fact I will argue that they are what made humans human. I went digging through their dna last year and Altai, Vi3315, and Vi3319 have the CYP21A2 rs6467 (C;T) variant
They were highly inbred and they were carriers for this form of Congenital Adrenal Hyperplasia (CAH) due to 21-Hydroxylase Deficiency. Even in its nonclassic form, this would have contributed to the low population numbers as any classic form would have been non-viable as well as resulted in evolutionary pressure to select for the genetic variants to compensate for the altered HPA-Axis. Neanderthals are most known for contributing to human specific DNA sets such as improved immune system, but if you go digging you will notice the larger pattern.
NCAH specifically results in higher neurogenesis. They were smarter. They also now had a bigger glucose preference and started to shift calories to grain. At some point between 130-70KYA there was enough excess calories from grain to not need to eat the dead. (see their teeth between this time) Admixture with modern humans occurs around 50-43KYA. These adaptations would have contributed to the loss of the mitochondrial DNA due to low female reproductive success compared to the higher male Neanderthal with female human success. The 2-4% that is found together is found together for a reason. They are incredibly valuable together.
This support for reduced HPA-Axis would have allowed for many other variants on the HPA axis and while not a single genetic variant, atypical HPA axis phenotype is associated with intelligence due to the enhancement in ability to detect unexpected events.
The glucose/grain preference with higher caloric density supported the higher population densities that occurred rapidly due to the Younger Dryas (last glacial period) and resulting agricultural and villages transition in Mesopotamia. These agricultural populations outcompeted other human groups while spreading the Neanderthal derived genetic variation.
This is within the larger story of Homo Sapiens. Because CYP21A2 variants are much older and come from the primate tree there would have been continuous and separate adaptations on each branch. Homo Erectus improved language today and is associated with better estrogen signaling while Neanderthals went down the immune system and grain path. Denisovan which did interbreed with Neanderthals reporting the same rs6467 variant might have pursued another branch of selection pressure such as TAAR, and I highly suspect, but have not confirmed, kept or selected for longer AR promoter reducing AR signaling. The most famous of all is Denisovan introducing a Zinc deficiency variant which is such a good adaptation it is found in all non-african humans and notably can reduce ER signaling directly via BHMT. The combination of each adaptation increases the fecundity of atypical HPA axis individuals and the associated intelligence.
Because humans can develop a zona reticularis in their adrenals (unlike marmoset which has partially solved this with an adaptation) the way HPA axis variants interact with steroidogenesis influences sexual differentiation and reproduction in homo sapiens there is constant push and pull.
Well they hard larger brains, more muscle mass, larger sinuses which aid in breathing in cold weather and possibly smell, denser bone structure, and a number of other possible advantages.
It has been proposed that the advantage we wield which led to out-competing / interbreeding with them may have been a superior ability to starve - i.e. use fewer calories - during periods like the last ice age.
"Neanderthals appear to have matured faster physically but had a slower reproductive tempo overall, with longer spacing between births. That suggests fewer offspring over a female's reproductive lifetime."
So my theory is that they could well have been more sophisticated in a lot of ways, but were just outbred.
Ive also read some out of wack theories like some conditions like autism could come from them since its more prevalent on white people. This would explain that a group that engages more socially creating bonds and more complex societal tribes in number would outnumber and extinguish these weird less verbal humans
It's far from conclusive, not representative of the majority of folks with autism diagnoses, and needs more replication and investigation. But it could be a thing. Speaking as a spectrum-y red-haired middle-european.
Well, ask it the other way around: what are the chances that despite having no evolutionary advantage over Sapiens, Neandertals survived as a distinct population for hundreds of thousands of years? Seems vanishingly unlikely to me!
They did have significantly larger brains than modern humans. There are many explanations of why they weren’t smarter than us, which I think is because many people would really like that to be true.
