R. Douglas Fields in Quanta:
One day, while threading a needle to sew a button, I noticed that my tongue was sticking out. The same thing happened later, as I carefully cut out a photograph. Then another day, as I perched precariously on a ladder painting the window frame of my house, there it was again!
What’s going on here? I’m not deliberately protruding my tongue when I do these things, so why does it keep making appearances? After all, it’s not as if that versatile lingual muscle has anything to do with controlling my hands. Right?
Yet as I would learn, our tongue and hand movements are intimately interrelated at an unconscious level. This peculiar interaction’s deep evolutionary roots even help explain how our brain can function without conscious effort.
More here.