Leave it up to a couple of barflies to come up with an event as baffling as the Man v. Horse Marathon. The idea was hatched in the back bar of the Neuadd Arms Hotel in Llanwrtyd Wells, where the owner overheard his patrons' fervent discussion about whether a man could beat a horse in a distance challenge, and decided to put it to the test. The mountainous 22-24-mile event has taken place every year since 1980, and whereas you might expect the horses to beat the humans without contest, that hasn't always been the case. Human runner Huw Lobb beat the lead horse for the first time in 2004, and Florian Holzinger repeated Lobb's achievement in 2007. The reason the competition is so close comes down to evolution. Many scientists believe we evolved to be persistent hunters that chased animals across the savanna until they collapsed. Our ability to lose heat through sweat is just one adaptation that gives us a leg up on horses and other quadrupeds, who pant to expel heat but have trouble doing so at top speeds. That's likely the reason humans have been able to win: those victories took place on hot days.