Back during the time between the 1940s and 1960s, before Norman Borlaug and his Green Revolution emerged and saved arguably a billion people from starvation, the prevalent thinking among the people in charge and the people who give those people their information was that humanity was edging very close to being doomed. This idea was based on the 18th-century thinker Thomas Malthus's theory that, given enough time, population growth will always exceed agricultural production; simply put, eventually humanity would reach the point where there was more people than food and a lot of us would starve to death.
Based on population estimates, it looked like we would reach this carrying capacity of agricultural production and an attendant mass dying off (estimates ran to a billion people, hence the number of lives Norman Borlaug is credited with saving) sometime in the 1970s or 80s. These projections very well may have been met had Borlaug not traveled down to Mexico and began to selectively breed a heartier strain of wheat through intensive farming techniques in common use today. By pressuring evolution to bend to his will, in just about a decade Borlaug created a hearty strain of wheat that yielded 2-3 times more per plant than previous varieties. When he replicated his success with wheat by creating a new strain of rice, Borlaug effectively defused what biologist Paul Ehrlich called the Population Bomb.
All of this is quite real. Just a few decades ago, very smart people believed we were on a course toward mass starvation and that course was thwarted by the initiative begun by one man (who won the Nobel Prize for his efforts).
Starvation wasn't the only reaper floated by the gloom and doom camp of the 60s when the population boom was discussed. There was also the matter of simply having too many people in one space, that space being Earth.
The work of a guy named John B. Calhoun found results perhaps more alarming than the starvation predicted by Ehrlich's Population Bomb. Calhoun was a behavioral researcher at the National Institutes of Health who built controlled worlds for healthy populations of mice (or rats sometimes) and studied the effects of population on the mice's society. He found invariably that the population always reached a point of no return where society collapsed into violence and an utter deterioration of social structure. Calhoun called this point the Behavioral Sink. Eventually the mice lost the ability to reproduce and died off. Food wasn't the issue -- there was plenty of it. The only pressure on the mouse civilizations Calhoun created was space; there were simply too many mice.
While we may have outfoxed the starvation question of the Population Bomb, what is disturbing about the implications of Calhoun's work is that even if we manage to provide for everyone, our society will still collapse, simply from sharing the planet with too many people. Interestingly, Calhoun found that mice who could handle high numbers of social interactions tended to fare better in an overcrowded world. I can't help but wonder if by shrinking the world via social media will either accelerate a slide toward the Behavioral Sink or better prepare us for dealing with it as we continue to grow across the planet.