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LIFE in the lab gives gerbils big testes and small brains, say German
researchers. All the Mongolian gerbils used in labs are descended from 20 wild
animals that were caught in 1935. Steffen Blottner of the Institute for Zoo
Biology and Wildlife Research in Berlin and his colleagues found that lab males
had heavier testes, and produced more sperm (Journal of Zoology, vol
250, p 461). They also had smaller brains than wild gerbils.