I had always been told that frowning made one look old.
Apparently, I had it entirely backward.
It’s smiling that makes us look old.
Melvyn A. Goodale, at Western Institute for Neuroscience, recently published how AI systems were even worse than people at being tricked by smiles into over-estimating an age.
Apparently, humans being bad at this was already well known, just not known to me.