Chesterton's Fence

Biological Parallel

The appendix seems useless—why not remove it? Turns out it's a bacterial safe house that repopulates the gut after infections. Vestigial structures often persist because they serve non-obvious functions: the panda's 'thumb' is a modified wrist bone critical for bamboo handling. Before declaring a trait vestigial (or a gene 'junk DNA'), understand why natural selection maintained it for millions of years. If you can't explain why the fence is there, you don't understand the system well enough to remove it safely.