New research shows that the processes involved in hair, fur, and feather growth are remarkably similar to the way scales grow on fish—a finding that points to a single, ancient origin of these protective coverings.
When our very early ancestors transitioned from sea to land some 385 million years ago, they brought their armor-like scales along with them. But instead of wasting away like worthless vestigial organs, these scales retailed their utility at the genetic level, providing a springboard for adaptive skin-borne characteristics. Over time, scales turned into feathers, fur, and hair.
We know this from the archaeological record, but as a new research published this week in the science journal eLife shows, we also know this because the molecular processes required to grow hair, fur, and feathers are remarkably similar to the ones involved in the development of fish scales.