If the organisms in a species now have trait T, and this trait now helps those organisms to survive and reproduce because the trait has effect E, a natural hypothesis to consider is that T evolved in the lineage leading to those current organisms because T had effect E. This hypothesis is "natural," but it often isn't true!
Processions that lack high stilts have nothing that catches the eye. What if my great-granddad had a pair that were twenty foot high, And mine were but fifteen foot, no modern stalks upon higher, Some rogue of the world stole them to patch up a fence or a fire.