I've heard claims like these several times, but this situation where individuals voluntarily limit their reproduction for the common good can't possibly be a stable equilibrium. It faces a coordination problem, more specifically a tragedy of the commons. As soon as even a small minority of the forager population starts cheating and reproducing above the replacement rate (by evolving either cultural memes or hereditary philoprogenitive behaviors that motivate them to do so), in a few generations their exponential growth will completely swamp everyone else. The time scales on which forager societies have existed are certainly more than enough for this process to have taken place with certainty.
In order for such equilibrium to be stable, there would have to exist some fantastically powerful group selection mechanism that operates on the level of the whole species. I find this strikingly implausible, and to my knowledge, nobody has ever proposed how something like that might work.
It happened in the real world, ergo the issue lies with your understanding of the system we're talking about and not with its inability to conform to your model.
I've heard claims like these several times, but this situation where individuals voluntarily limit their reproduction for the common good can't possibly be a stable equilibrium.
You're looking at this backwards. This is the reproductive context in which humanity evolved, and the Malthus-driven upward spiral of population and competition is the result of comparitively recent cultural shifts brou...
From Mike Darwn's Chronopause, an essay titled "Would You Like Another Plate of This?", discussing people's attitudes to life:
Conclusion, graphs, and references in article. As usual, I recommend reading Chronopause.com as Darwin has many good articles; to quickly link a few: