Overpopulation Makes Sci-Fi Writers Shit Their Pants, But Real-Life Overpopulation Isn't The Problem
There's a whole category of post-apocalyptic movies in which humanity's worst enemy is not zombies, aliens, or cyborgs, but our own genitalia. As in the whole planet is overpopulated to the point of disaster, with the frantic masses being forced to fight over the seven remaining crumbs of food and half-drop of oil.
You might remember recent examples, like the sprawling, slum-infested Dredd or the crowded planet-sized ghetto in Elysium ...
The first resource to run out was soap.
... but this trope goes way back to classic films like Soylent Green, in which the government rounds up hordes of people in physical scooping dump trucks and then solves the lack of food by ... well, we don't want to spoil the movie for you. Let's just say it's not a good dinner date flick.
Unless you've both spent a season in the Andes and miss the cuisine.
The idea that we're heading toward a population crisis might seem frighteningly feasible to anyone who has ever visited a shopping mall, but the problem isn't as dire when you look at the data. Economists like Max Roser point out that across the world, fertility rates are in fact shrinking. Today, the average household has around 2.5 children, as opposed to the five or six that our horndog ancestors had on average during the 1960s.
If a little thing called "history" is to be believed, this (in conjunction with increased modernization, lower poverty rates, and a rise in education levels across the world) means population sizes will level off fairly soon. You see, back during England's Industrial Revolution, as living conditions improved and mortality rates fell, families that were used to having many children per household no longer needed to, because the ones they had survived childhood now. The abundance of unexpectedly non-dead kids led to a surge in population which took almost a century to correct itself, but that process is happening much faster in today's newly developed countries. This is why your parents seemed to have 27 aunts and uncles, while you have like three. According to UN projections, the Earth is expected to reach around 10 or 11 billion people in the next hundred years, then sorta cool it with the people-making.