The last thing I learned.

What is the last thing you learned?

The last thing I learned came from a segment on the television 📺 program QI.   It is that when your dog sees you again after an absence of hours,days etc they will raise their left eyebrow when they first lay eyes on you again. Apparently this only occurs for a few seconds so I am wondering how researchers found this out.  To me Lily looks at me all the time with wide puppy dog eyes 🐶.