Are you an expert in this field? I’m not so honestly you don’t have to know a lot to know more then me, but here are my guesses:
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.
A quote from an article[1] about the latest research about a "vegetarian gene":
"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.
I don’t know if upper paleolithic Europe had temperate climate. Given that there was a pretty deep ice age at the time I would definitely consider that insular population in a harsh climate. Also like I said above game is seasonal, and winter is exactly when hunting becomes easier as game is more vulnerable in the absence of foliage and takes greater risks as their own food source is scarce. If I were to guess, winter is when most pre-neolithic societies did most of their hunting in temperate regions, and consequently ate most of their meat. I would also guess that in late summer and early autumn months went by without any meat what so ever (except fish, some birds, and scavenged meat) as roots and nuts are plentiful and game is the hardest to hunt.
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.
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.