All the nomadic tribes, people living in mountainous areas, hunter gatherer societies in temperate climates,...
Though the question itself is pretty meaningless or misleading, since on average people today do not eat meat in almost every meal at all.
I doubt that hunter gatherers in temperate climate ate 100 kg of meat per year. This kind of meat consumption only existed were plant based diet wasn’t available at all. To contextualize, 100 kg (average yearly USA meat consumption per person) is around 2 kg per week, that is around 150 grams per meal (given 14 meals per week). I would say that qualifies as meat in almost every meal.
Which is almost everywhere on the planet beside tropics and subtropics before agriculture came to existence. It was natural for humans to live on a predominantly meat diet for a lot longer than it became fashionable to live from plants only.
>To contextualize, 100 kg (average yearly USA meat consumption per person) is around 2 kg per week, that is around 150 grams per meal (given 14 meals per week). I would say that qualifies as meat in almost every meal.
The population of the USA is only 4% of world population and Americans probably eat more than 2 two meals a day. So no, on average we do not eat meat almost every meal.
a) You underestimate how forested the temperate regions were before humans started significantly altering them well after the agricultural revolution.
b) You underestimate how well humans can gather and store non meat foods without agriculture. I bet an average group of humans knew where there were fruitful nut trees, know when they were ripe, know how to store the nuts, and know how to sprout and grow knew once in a favorable location. I bet roots have the same story. See you don’t need agriculture to grow things, and I bet humans have been doing it for hundreds of thousands of years.
c) You underestimate how hard it is to hunt with stone and bone tools. Apart from fishing, game is mostly seasonal in the temperate regions, so there would always be seasons where meat was scarce. It takes a ton of effort and coordination to hunt a single animal, you are not always succesful, and when you are, then storing the meat becomes an issue. So your best bet is to share the meat with the whole group, and probably leave some for other scavengers.
As I said, I’m not an expert, but realistically I don’t see how pre neolithic humans could have eaten even close to 100 kg a meat per year.
"Furthermore, before the advent of farming, pre-Neolithic hunter–gatherers throughout Europe had been subsisting on animal-based diets with a substantial aquatic contribution, in contrast to the plant-heavy diets of recent European farmers."
Temperate climate means 4 distinct seasons and plants rest from autumn to spring. Which makes it impossible find and eat fruits of plants for 6 months. Sure you could store some nuts, but that will not cover you dietary needs for long.
[1] https://www.nature.com/articles/s41559-017-0167.epdf?author_...
EDIT: I would also like to add, that the original claim was that it is in human nature to eat meat. If that were true, people wouldn’t have stopped doing it after the neolithic revolution as farming spread and plant based food became even easier. I mean we kept feeding meat to our dogs as it is definitely in the wolfs nature to eat meat.
What you say might be true of the wolf nature—hence you shouldn’t feed your dog with vegetarian diet. But humans are not dogs, and only insular population of us living in harsh climates such as the arctic have historically eaten meat as our primary diet. And even then, plant based food is brought to these populations, people there very much consume it. If there is any human nature that rules our eating habits it is the fact that we are omnivores and eat what is available.