High up in the steppes of Kazakhstan is where it may have first happened: a human decided to climb atop a horse instead of killing it for meat. The act seems trivial today, but nearly 5500 years ago it would have been revolutionary."Horse domestication was a landmark moment, a bit like the invention of the wheel," says Alan Outram of the University of Exeter, UK.By domesticating horses, humans created the first form of land transportation, vastly expanded the region within which goods could be t