Just learned that we’re the only animals with chins, and am reeling. REELING. https://www.theatlantic.com/science/archive/2016/01/were-the-only-animals-with-chins-and-no-one-knows-why/431625/
We're the Only Animals With Chins, and No One Knows Why

Despite much chin-stroking.

The Atlantic
Maybe re-learned, actually. I think I’ve encountered it before. But it didn’t prepare me.