On Vestigial Structures

Do you know what vestigial structures are?This write-up is a slightly modified version of a commit description I have written for $WORK with some help from ChatGPT .

In a nutshell, they are remnants of structures that were functional in an ancestral species but have lost much or all of their original function in the descendant species.

For instance, some snakes, like pythons and boas, have tiny remnants of hind leg bones, which are vestigial structures from when their ancestors had legs. Birds like ostriches and emus have wings that are too small for flight. These wings are vestigial structures as well, remnants of their flying ancestors. Even humans have some, like those small muscles around their ears. These muscles were once used by our ancestors to move their ears, similar to how many animals can today.

Sometimes, vestigial structures are not just useless, they can be harmful. Take our wisdom teeth. They were handy to our ancestors, who had larger jaws and a diet that required more chewing. Sadly, they have become problematic for many modern humans.

Anyway, ocaml-migrate-parsetree is a deprecated OCaml library in $WORK’s dependency tree that will never be compatible with OCaml 5, but it turns out we do not need it anymore .