A new study conducted by scientists from China, Sweden, and the United Kingdom reveals that the human middle ear evolved from fish gills.
According to Gai Zhikun, a Chinese Academy of Sciences researcher and the first author of the article "The Evolution of the Spiracular Region From Jawless Fish to Tetrapods," there is ample embryonic and fossil evidence that the human middle ear evolved from a fish"s spiracle.
But where the spiracle came from has puzzled academics for over a century. Chinese scientists have eventually found clues to the mystery in fossils unearthed in the provinces of Zhejiang and Yunnan, which provided anatomical and fossil evidence for the origin of vertebrate spiracles from gills.
The fossils were taken to the Swiss Light Source in Switzerland for non-destructive scanning and 3D reconstruction.
Gai said the discovery explains why human ears and mouths are connected, thanks to an ancient breathing passage passing from a fish"s mouth through the gill.
"It"s an evolutionary fish remnant from more than 400 million years ago, which we now call a Eustachian tube," Gai said.
