Why? Animals don't usually starve to death. Nor do humans. Any generation has an established means of extracting what it needs from its environment. Starvation is an exceptional occurrence.
That's pretty recent, actually. According to the UN, in 1947 the global rate of undernourishment (a year or more of insufficient food) was approximately 50%. In 1975 the rate was 35% in the developing world, according to the Food and Agriculture Organization. Famine has always been with us, at least until the last decade or so. Until very recently, a single crop failure could devastate a community. Huge swaths of the world were vulnerable to famines. Have a look at the mortality from famines by decade since the 19th century, from the Our World In Data project: https://ourworldindata.org/wp-content/uploads/2018/03/Famine... , or the chart of famine deaths and durations from the same: https://ourworldindata.org/wp-content/uploads/2018/03/The-nu... . And this starts in a relatively modern timeframe. There's a good reason that famine was included as a horseman of the apocalypse, along with war, pestilence, and death. It is only recently that famine has been reduced to an exceptional occurrence. In previous generations, undernourishment was the norm, and famine not uncommon.
If the tribe gets too big, it can quickly deplete the resources in the area, especially when helped by natural phenomena like drought.
N.B. animals have evolved in harmony with their environment. In general you get the perfect ratio of predators to herbivores to plants. If there are too many herbivores in an area and without natural enemies, that can quickly turn the environment to a deserted land. There are actually stories around like how introducing wolves in the Yellow Stone national park has saved its rivers.
Humans on the other hand are too adaptable for the environment. We can live in any environment and without natural enemies to keep our population in check, nature’s laws don’t apply to us.
So could we deplete our resources 15,000 years ago?
Hell yeah. In fact that’s the number one reason for the migrations of early humans between continents.
>In general you get the perfect ratio of predators to herbivores to plants.
This is just flat out wrong. Both predator and prey animals starve to death all the time, often due to the impact they have on their environment but also due to a myriad other natural events. It's known as the predator-prey cycle and is a series of population booms and busts caused by over consumption and over population. Here's a video that gives a very basic explanation.
My folks live out in the middle of the woods, and my dad has several times observed that there will be a bunch of rabbits and not very many coyotes running around for a year or two, then there will be a lot of coyotes and not very many rabbits for a year or two, then there will be a bunch of rabbits and not very many coyotes again.
Preditors prey relationships are far from perfect. What's missed is locally things can get out of whack, but both preditors and prey move around. Further the vast majority of species have died out, and that trend shows no sign of stopping.
