The video: Remember our old pal robo-cheetah? The Defense Advanced Research Projects Agency (DARPA)'s four-legged speedbot set another milestone when it recently hit 28.3 mph on a treadmill, besting its previous record of 18 mph. (Watch below.) For those keeping score, that's faster than Usain Bolt, the fastest man on Earth, who peaked at a mere 27.8 mph in 2009 during the 100-meter sprint. Of course, robo-cheetah tripped and fell on what would have been its face (if it had one) a few seconds after reaching its peak speed, and is not yet fit to keep pace with real cheetahs, which regularly eclipse 60 mph. DARPA's experimenting with bio-inspired military machines like robo-cheetah and robo-mule to develop new ways of delivering military supplies across tricky terrain.

The reaction: It's worth noting that robo-cheetah "has only been tested on a treadmill in a lab," says Deborah Netburn at the Los Angeles Times. It doesn't have to haul around a heavy power source, and it has a "boom-like device" that props it up and keep it centered. Still, humankind, "you appear to be losing your supremacy." In any case, you should watch the video and be "humbled and/or terrified," says Sebastian Anthony at ExtremeTech. I'm not sure why, "but it's actually quite scary to watch a robot almost destroy itself while doing the bidding of its master." Take a look: