This Great Lakes fish may have evolved to see like its ocean ancestors did

In the dark waters of Lake Superior, a fish species adapted to regain a genetic trait that may have helped its ancient ancestors see in the ocean, a study finds. 'Evolution is often thought of as a one-way process, at least over deep time, but in this example, over 175 million years, we have this reversal back to a much earlier ancestral state,' one of the researchers says.

source https://www.sciencedaily.com/releases/2021/01/210121131913.htm