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Junk DNA and evolution

Yale Medicine Magazine, 2009 - Winter

Contents

Humans can handle tools and walk upright thanks to a handful of letters in their genome, Yale scientists said in a report published in Science in September. Evolution, they suggest, may have been driven not only by changes in genes but also by changes in the sequences that control them.

Some sequences, previously thought of as “junk DNA” because they do not code for proteins, regulate genes that direct human development. With colleagues in California, Singapore and the United Kingdom, the Yale team characterized in mouse embryos a human sequence that had changed since humans and chimpanzees diverged. This sequence drove gene expression at the base of the mouse versions of the primordial “thumb” in the forelimb and the “great toe” in the hind limb.

“The long-term goal is to find many sequences like this and use the mouse to model their effects on the evolution of human development,” said James Noonan, Ph.D., assistant professor of genetics and senior author of the study.