One billion people. That's how many active monthly users Facebook has accrued in the eight years of its existence, the company announced today.

It took the population of modern humans about 200,000 years to reach that number, a milestone that was hit, demographers believe, just over two centuries ago in 1804 (bearing in mind that population tabs, then and now, are not exactly precise). Since then, human population has just exploded, enabled and protected by advances in medicine, agriculture, and hygiene. In the past year, it is estimated that the human headcount hit 7 billion.