A waltz over evolutionary timescales: Why it's so hard for animals to invent a new mating dance

"Love makes fools of all of us," wrote 19th-century novelist William Makepeace Thackeray.

A moment spent watching the pigeons at your local park suggests he was right: males with puffed-up, shimmering necks hop, pirouette, coo, and bow to capture the attention of unimpressed females. ...