If I were to bet my money I would bet it on social structure or a disease.

- Homo Sapiens had tribes 100-200 people when Neanderthals had 20-30. They were outnumbered. I'm not suggesting brutal wipe out, but competition for resources.

- we "won" because we were immune to a disease be brought from Africa.

A paleoanthropologist remarked that the most striking and reliable difference between finds at Neanderthal and contemporaneous sapiens sites was that Neanderthal artifacts were never from sources far away, which he interpreted to mean they had no trade network.

There are many ways to interpret that: xenophobic? susceptible to disease? militantly self-sufficient? not interested in decoration? (Most trade goods are decorative.) no language skills?

There is other evidence that Neanderthals had no reliable access to fire: that if their banked coals died, they could not start a new fire, or get a light from another band.

As someone with an abnormal amount of Neanderthal DNA (relatively speaking for modern populations), I do seem to run a higher metabolic rate. I'd never thought to associate the two though.

How much do you have ? If very high I wonder how it can happen, since I'd guess ancient admixtures should dilute a lot over time.

It's about 0% for sub-Sahara Africans, and in the 1% to 4% range for the rest. [1]

This may not mean exactly what you think it means though. Your non-Neanderthal genes are also almost identical to the Neanderthal ones, otherwise interbreeding would have been impossible. It's just that genes come with slight variances that can be used to trace ancestry.

E.g. you may also have heard that humans and chimpansee DNA is 98.8% identical, so there is obviously a different type of similarity metric being used there

[1] https://www.science.org/doi/10.1126/science.1245938

Some of the very similar Neanderthal variants of genes are manifest as important phenotypic differences though. Traits ranging from hair straightness, sneezing after dark chocolate, to severe COVID risk. Some alleles are now suddenly quite deleterious due to modern lifestyles, like the CHRN3 gene variant, but wasn't before widespread smoking.

How did you find this out? Also could I use my genome data from ancestry.com etc to do the same

I believe Neanderthals were also less pack oriented, so humans just had bigger powers in numbers.

It's also fascinating that Neanderthals soundly beat us in the first round of incursions, and 50k years later humans presumably wiped them out entirely + all other variations of homonids

Neanderthals were better able to cope in colder climates than modern humans. The climate may just have pushed the immigration of them many several thousand years back.

From the comments above, I thought it was the other way around? More energy efficient metabolism resulting in greater range of biomes to permanently settle?

Evolutionary The Tortoise and the Hare

It is also quite possible that the Neanderthals were stronger, faster, smarter, and more moral/ethical, and that sapiens were simply crueler, more diabolical, more savage.

It is quite difficult to imagine a species that is more vicious to even its own members, let alone members of other species, than ours is.

the percentage of deaths caused by other members of the same species:

Hylobates lar - 8.93% Gorilla beringei - 5.00% Pan troglodytes - 4.49% Hylobates agilis - 4.17% Nomascus hainanus - 1.00% Pongo abelii - 0.82% Pan paniscus - 0.68% Nomascus gabriellae - 0.59% Nomascus leucogenys - 0.59% Nomascus siki - 0.59% Nomascus concolor - 0.36% Gorilla gorilla - 0.14%

Modern humans - 0.14% Medieval Age, Old World - 12.08% (± 7.15%)

https://www.nature.com/articles/nature19758.epdf?referrer_ac...

The paper indicates that at times and levels of.social organisation our lethal violence rate increases well above the phylogenically predicted 2% — see Fig. 3c the contemporary band and tribe median estimates of 5±1% which are probably considerably more accurate than inferring from prehistoric remains). Other work suggests during resource scarcity hunter gatherer lethal violence shoots way up as well. I'm actually not sure what my point was, other than I suppose early humans under the conditions of contact with Neanderthals probably were on par with the most violent of phylogenetically similar animals.