Study Reveals Mammalian Outer Ear Evolved from Fish Gills

New research uncovers a surprising evolutionary link between the elastic cartilage of fish gills and the outer ears of mammals.

Researchers discovered that the elastic cartilage in mammalian outer ears shares a genetic origin with the cartilage in fish gills.
The study used genetic enhancers to demonstrate that human ear enhancers are active in fish gills and vice versa, revealing a deep evolutionary connection.
Experiments showed that the transition from gills to outer ears occurred progressively across species, with cartilage relocating to the ear canal in reptiles and becoming prominent in mammals.
Findings suggest that elastic cartilage similar to that in mammalian ears may have first appeared in ancient marine invertebrates over 400 million years ago.
The research highlights how evolution repurposes existing genetic programs to create new structures, offering insights into the development of complex anatomical features.