One of the several problems that have emerged since humanity decided to evolve away its tail, is that letting people know how you're feeling is more complicated that it needs to be.
For animals with tails, it's oh so easy: wagging means excited, not wagging means not excited: job done. Instead we have to rely on facial analysis, body language and passive aggressive Facebook updates to tell how we're supposed to be reacting to the people around us. Awkward.
Luckily a new Japanese invention hopes to change all of that. Shippo is a human tail controlled - apparently - by the brain. It detects when areas that usually indicate happiness of excitement, and wags. It also uploads your mood to an app that others can follow, looking for areas where people are generally well-disposed.
The idea has been around for a little while, but recently popped up again on Reddit with more calls to bring the invention to our shores.
Others were more sceptical: "Hopefully this will be the Comic Sans of the fashion industry, maybe replacing the fedora" said one Redditor.
Take a look at how it works, above. Would you use it?