Neanderthal outlived the Cro Magnons. It was a short lived type.
Like all early people Neanderthal had brow ridges, an occipital bun, and a back sloping forehead.
Modern humans from 125,000 years ago had higher foreheads, much less brow ridge, like it had unfolded upward. They had a very round brain case, as seen from above, and had a dorsal crest and occipital bun. This higher forehead then shows in older homo erectus lines back in Africa, showing an extended breeding pool.
It is not just the skull, but the shape of the brain, and there Neanderthal had a much larger occipital region, where vision is processed. We are sight hunters, with weak ears and nose, compared, so they were likely very visual.
Seen from above, their skulls are longer than wide.
The next model, 40,000 years ago, has traits of both, they are called Long Heads, skulls longer front to back than wide, they have the high forehead, and instead of the back of the skull ending in a point, it unfolds, reducing the occipital bun. They are now called long oval.
While early species have a rounded skull along the sides, coming up to a dorsal crest, a new ridge formed running down both sides, from the top of the temple to the back of the skull, and the dorsal crest diminishes. Another unfolding, adding volume in the speech area, temporal lobes, and this design reaches full development in Cro Magnon, who quickly die out as they seemed to have been too big headed.
The design continues with smaller skulls of the same design.
The high forehead spreads south, among round heads, while the long heads are found to the north, which points to a Neanderthal mix, as they had larger brains, and long skulls. Prior changes had taken millions of years, the change in the north comes suddenly, and produces Cro Magnon.
That would fit with a slightly higher problem with giving birth to such big heads, for when most were near 1.5 meters, Cro Magnon men were well over 2 meters. In the same design the smaller models survived better, so that is what is left.
Brow ridges, dorsal crests, occipital buns, have survived, recently, but as rdos says, babies with different traits, skull form, covered in hair, and anything else seen as a defect, were left in the woods. They were not the real child, that had been taken by elves, which left a changling in it's place.
Skulls do point to a Neanderthal mix, but intelligence is another story, most brains conserve energy, turn on the TV, sit on the couch, which takes less energy than sleeping.
Aspies do have one displaced early trait, their focus on special interests is much like the Neanderthal who's special interest was killing something to eat. Tunnel vision, obsession, are hunters traits, and we do find modern applications. Much like their seasonal life, sometimes they fed along the coast, sometimes the herd migrations, sometimes hunting game that did not migrate.
Fishing skills do not work in hunting, so one obsession stops, another starts. What would have worked for Neanderthal is still shown in Aspies.
While intelligence may be seen as an aspie trait, it is as a splinter skill, learning everything about one subject, at the cost of ignoring eating, sleeping, bathing, talking, but we do get things done.
I was told I was not the smartest person around, but I was the only one who would spend hundreds on books, study a subject till I mastered it, which had nothing to do with my life or income. I like Geology.
There have been a long list of special interests, and it does run out. What is known can be learned, but after a few, the space between come into focus, and no one has ever looked there. We learn parts, but reality is the function of a whole system which no part can define.
In Consilience, Edward O. Wilson calls for just such general studies to unify the knowledge we have into larger systems.
We are naturals. Most never master any one subject, but it is entry level for seeing how that knowledge fits with other fields, which are where new discoveries come from.
As this has been mostly done in northern Europe, I would see it as a carryover of Neanderthal hunting traits.
We are children who never stop asking, "Why."