Humans began migrating out of Africa and across the rest of the world about 100,000 years ago. But it was only around 12,000 years ago, with the invention of agriculture, that large and permanent populations began to emerge. Continued improvements in agriculture and medicine, combined with the development industry, had contributed to an exponential expansion of the human race, as the video below by the American Museum of Natural History powerful visualizes:
While the human population is projected to increase to over 11 billion by 2100, the rapid decline in fertility across much of the world (including developing countries) may indicate — for the first time in history — a peaking of the number of humans, and much earlier than expected.
H/T to Aeon.