Check out this article if you want to look into the age old debate of who can run faster, man or horse.
Here's a few extracts;"Every year since 1980, Llanwrtyd Wells has hosted the Man Versus Horse Marathon, which pits hundreds of runners against dozens of horses with riders. On two legs or four, contestants take on 22 miles of challenging trails laced across a dazzling green countryside. They trot through fragrant pine forests, scramble up mountainous rock-strewn sheep trails, cross rolling moorlands, and ford rivers. In June 2004, for the first time ever, the human won."
"...under the right conditions, they can also outrun just about any other animal on the planet—including dogs, wolves, hyenas, and antelope..."
"Chimps and other primates have little buns. Our own rear ends are huge; the upper part of the gluteus maximus is greatly expanded. Although few scholars have studied its role in running, the butt is, according to Bramble, "basically a substitute for a tail.""
Here's the article: http://discovermagazine.com/2006/may/tramps-like-us