What I remember being taught in school is that Neanderthals were more intelligent than Cro-Magnons in many ways, but were ultimately less successful (evolutionarily speaking) because they were less social.

By their art, their technology, the environments they could live in, their slow rate of adaptation to change. On and on.

But isn't all that essentially cultural knowledge?

If you compare the art and technology of Homo sapiens 50,000 years ago vs 50 years ago... it's clear that 50,000 years ago gives no inkling of Homo sapiens' intelligence.

So how could we possibly infer that Neanderthals were less intelligent? How could we possibly separate their intelligence from their state of cultural and technology evolution?

Edit: indeed, a quick Google search reveals that the idea that Neanderthals were less intelligent than humans has no real evidence, that it's now considered to be an outdated/discredited view. So wherever you seem to be getting your facts and conclusions from, appears to be wrong.

I've read that Neanderthals were actually more intelligent, but that they were less social than Sapiens. Sapiens ganged up on the more solitary Neanderthals and overwhelmed them through violence or breeding.

Not necessarily wrong, but there isn't much evidence either way.

Interestingly enough, homo sapiens was also really slow to adopt to change for a very very long time. Basic toolkit was unchanged for something like 1M years.

Then cam the Tonga event, homo sapiens population is reduced to less than a thousand individuals (perhaps much less), and suddenly we got creative.

Innovation wasn't a thing before that. It has been everything since.

I was under the impression that the evidence for the Tonga event being the driver of a human bottleneck has weakened in recent years. Is that incorrect?

Think you mean Toba volcano in modern-day Sumatra, Indonesia (https://www.npr.org/sections/krulwich/2012/10/22/163397584/h...)

> their slow rate of adaptation to change

This particular failing of Neanderthals resulted more from their extremely small effective population size, i.e. spiralling inbreeding, which eventually lead to total population collapse.

There's not a lot of evidence to support that, though there is some. They could have been wiped out by disease, as opposed to any superior intelligence on the part of us sapiens.