According to Malthus's metrics we are waaay past the world population limit that results in total anarchy, famine, war etc. He never took into account technological progress. I think we'll reach a limit to human capacity for living in these completely "unnatural" social systems before we ever reach problems with a lack of resources. If you believe in the concept of a technological singularity, and that the exponential progress of technology since the industrial revolution is an indication we are heading towards it, lack of resources may be a distant problem, if one at all. We're a resourceful species. We may be victims of our own success more than anything, and I'm not just talking about exploitation/destruction of natural ecosystems that support us.
For example, the infamous Behaviour Sink experiments. It's possible to read too much into Calhoun's experiments, but there's clearly some unsettling parallels with humans. Mice as a a social mammal are similar to humans in a lot of ways. Their fast reproduction cycle and ubiquitousness is not the only reason they are the most practical test species, for psychological and biological testing alike.
http://io9.com/how-rats-turned-their-private-paradise-into-a-terrifyin-1687584457Universe 25 started out with eight mice, four males and four females. By day 560, the mouse population reached 2,200, and then steadily declined back down to unrecoverable extinction. At the peak population, most mice spent every living second in the company of hundreds of other mice. They gathered in the main squares, waiting to be fed and occasionally attacking each other. Few females carried pregnancies to term, and the ones that did seemed to simply forget about their babies. They'd move half their litter away from danger and forget the rest. Sometimes they'd drop and abandon a baby while they were carrying it.
The few secluded spaces housed a population Calhoun called, "the beautiful ones." Generally guarded by one male, the females—- and few males — inside the space didn't breed or fight or do anything but eat and groom and sleep. When the population started declining the beautiful ones were spared from violence and death, but had completely lost touch with social behaviors, including having sex or caring for their young.
https://www.youtube.com/watch?v=0Z760XNy4VM
