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Seeking an answer, the research team from the Graduate School of Science at Osaka Metropolitan University took a look at a rather taciturn animal: fish, more specifically, Neolamprologus savoryi, a cooperatively breeding cichlid fish.

"When the cichlids were young, they had this huge plasticity and were able to alter their physiology in order to cope with the turbid environmental conditions," Tiarks said.

For a total of nine months, first author Dr. Carolin Sommer-Trembo recorded the "exploratory behavior" of 57 different cichlid species at the Southern shore of Lake Tanganyika in Zambia.

Some cichlids specialize in eating plankton; others live on aquatic plants, eggs, invertebrates, and even other fish.

Although several kinds of fish colonized this lake around the same time, only cichlids took off, forming 500 species in less than 17,000 years, the team reports today in Nature.