Originally published in 1968, the best-seller The Population Bomb warned of the perils of overpopulation: mass starvation, societal upheaval, environmental deterioration.

The book was criticized at the time for painting an overly dark picture of the future. But while not all of the Ehrlich’s dire predictions have come to pass, the world’s population has doubled since then, to over seven billion, straining the planet’s resources and heating up our climate.

Can the earth continue to support an ever-increasing number of humans?