Dumb man walking...

Chimpanzees scampering on a treadmill have provided support for the notion that ancient human ancestors began walking on two legs because it used less energy than quadrupedal knuckle-walking, scientists said. [...]

And if there's one thing we know, it's that the Chimpenfuhrer does not like to expend a lot of energy.

Bipedalism is a defining characteristic of the human lineage and marked an important divergence from other apes.

How does one detect a difference?

Chimpanzees are the closest genetic cousins to people. [...]

Ergo, presidents are the closest genetic cousins to chimpanzees.

"This paper provides strong support for the fact that energy savings played a role in the evolution of bipedalism," one of the scientists, University of Arizona anthropologist David Raichlen, said in a telephone interview.

So when Bush hangs out at the ranch or Camp David for 40% of his presidency, or just feels like strummin' the gee-tar while "underprivileged" people die, he is, in fact, proving that evolution does exist.