Is that true or an assumption we make? How do we know for sure that this was the case for prehistoric tribes? I mean, most habitats aside from the desert are teeming with edible items.
There was this documentary about a first contact with an amazon tribe.
I remember an interview with the (very young) leader of the tribe who
was talking about how life was in the jungle and iirc he described it as
very miserable, they wouldn't eat for days at a time, bugs everywhere ++
Most habitats indeed are full of living organisms compatible with human dietary needs. The problem is, sometimes you're so good at killing that you just kill all the food before the food has time to reproduce itself. Or maybe it just doesn't rain for two months. Or myriad other contingencies that make nomadic life precarious.
edit: and as bad_user pointed out, thats a huuuge reason itself to even be nomadic
Humans are also exceptionally good at storing fat while also saving energy the moment someone misses a meal. There is a lot of research indicating regular fasting is actually beneficial to ones health, which in context would seem to only make sense if we were adapted to regularly encounter times of poor food availability. With people relying on stored fat from gorging on foods from better times and what you could find while traveling instead of dedicated forging or hunting. Once you encounter a better area with more game and natural food sources you stop again for a little while.
Our ancestors were way more in tune with their surroundings, and knew how to moderate their consumption so as not to decimate their food supply populations. We have evidence from many Native American tribes.
Just because modern, industrialized humans are out of touch with natural limits doesn’t mean we were always like this.
You might be interested in Jared Diamonds "Collapse". He's aggregated a lot of evidence of many societies that over populated, over consumed and died out. Not all did though and your technically right in that the survivors (our ancestors) avoided this fate. I just think we should be weary about any claims that peoples of the past were any smarter about their self preservation than we are..
I'm not trying to argue that ancestors were smarter.
For our own political purposes, it's probably best if the narrative becomes "all of our ancestor societies binged themselves to collapse, so we need to be very careful about our own habits" although it's not exactly true that all groups did that.
North and South America were teeming with large mammals before humans came to this hemisphere 10-20kya. Saber-tooth cats, horses, ground sloths, enormous camels, mammoths, mastodons, ....
it's the documentary talked about here, I highly recommend it: https://www.theguardian.com/world/2014/aug/01/amazon-tribe-m...