If you've got about 6 and a half minutes, I recommend watching this video from the American Museum of Natural History documenting human population through time.

If you don't, look at roughly the last 2 and half minutes. Start at 4:10 and watch the impact of modern technology and medicine on the growth of human population.

Click here to see it on YouTube

There are a lot of us now. I wonder if they want to join Gotham :)