Wall-E fell in love with another robot in the movie named after him. Researchers have yet to create a sentient machine, but a breakthrough could be on the horizon. John M. Heller/Getty Images hide caption

itoggle caption John M. Heller/Getty Images

A capuchin monkey riding a dog. Tim Lepard, owner and creator of the Monkey Rodeo, says his animals are treated humanely. Courtesy of Tim Lepard hide caption

itoggle caption Courtesy of Tim Lepard