But the data visualization above, created by Derek Watkins, is much more simple than a brain straining illusion. By sliding the bar above the map (click here to try it) you can get a good sense of where human populations tend to cluster throughout globe, using data from CIESIN Gridded Population of the World.
The map above shows a very low population density -- about as dense as the state of South Dakota -- so many of the human inhabited places on earth show up in black. But as you slide the bar farther to the right population density increases and the number of very dense places dwindles down to a few concentrated urban islands, located most prominently in Asian countries. Here's what the world of 300 people per square kilometer -- a few square kilometers more than the density of Connecticut, the fourth most densely populated state in the U.S. -- looks like:
Other than the clear outline of India, the image above hardly looks like a map of the world. And in the U.S. it's hard to distinguish a dark spot representing density from dirty spots on your computer screen. The map is somewhat misleading, however. More than 200 of the largest cities in the U.S. have population densities over 300 people per square kilometer. So it's not as if the U.S. doesn't have these population densities, it's just that they aren't as concentrated at the rate they are in places like India and China. But you get the picture: the eastern side of the world is much more dense than its western counterpart.
Go here, to explore the interactive graphic and our world's population density.
More on population density: