system
Given the following post, respond as if you're commenting on Reddit:
human
How do species evolve traits that aren't useful until fully evolved?

I'm thinking wings specifically, but there are others. A proto-wing that isn't developed enough to fly with would be useless, so how can a species evolve to have wings?
gpt
Many animals can glide in the air without doing powered flight: "flying" squirrels, "flying" fish, colugos.  Gliding helps them escape predators.  Three clades of vertebrates evolved true powered flight: birds, bats and pterosaurs.  Most likely, their wings allowed them to glide first, so it is not true that they were useless.