What it also demonstrates, however, is the impact of some of humanity's most dramatic failures.
When you follow the link, you'll see a chart. Each circle on the chart represents a country, with the size of the circle representing the size of the population. When you press "play," the mass of dots and circles -- the world's population, in aggregate -- moves together toward the lower right of the graph -- representing everyone on Earth having fewer kids and living longer lives.
Soon though, a few dots seem to zig-zag away from the group for a moment, before sharply reversing course and rejoining the global trend.
Hovering over the errant dots, and noting the year on the axis below, reveals the stray dots to be countries amid catastrophe. Rwanda in 1994, Cambodia in 1974, Bangladesh in 1970 and Iran in 1982 all bounce like super balls for a year or two.
The result is a shockingly clear demonstration of the cost of political failure. As the dots race left across the chart, you're seeing that country lose a generation in the Rwandan Genocide, Cambodia's Killing Fields, the East Pakistan succession (often called the Bangladesh Genocide) or the Iran-Iraq war.
It's arresting and terrible, if apparently unintended. For a bunch of dots, it's also unexpectedly human and affecting. When a statistician does The Pieta, it will look something like this.
(We're working to get the animation embedded here; for the moment, follow the link -- it's worth the click).