How our ears evolved from the gills of 400-million-year old fish 
By Cassidy Ward US Source: SYFY WIRE 6/20/2022
Cassidy Ward
Credit: Zhikun Gai et al
In the 1995 film Waterworld, severe climate change has caused global changes to the Earth’s surface, forcing humans to live on boats or floating cities and scrape out a living on the high seas. It also drove evolution in at least some humans, as evidenced by the Mariner’s gills, tucked neatly behind his ears. Audiences may have found that unbelievable, but it might not have been as impossible as it seems.
 

If you trace our evolutionary lineage far enough into the past, humans and all other land-living vertebrates will find primitive fish as their many-great grandparents. Of course, there are millions of years of evolution standing between our gilled ancestors and ourselves, and it’s highly unlikely we’d adapt them again on so short a timescale, but the positioning behind the ears might have been right on the money.

 
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