The Making of the Fittest
Every step in evolution - every adaptation or change in form - involves changes in DNA. The DNA of living species thus contains a record of how each evolved. Very recently, biologists have begun to mine this record for insights into how species have adapted to the planet's varied and diverse habitats. From fish that live in sub-freezing water to birds that communicate in ultraviolet colors, Dr. Carroll describes our new understanding of how the fittest are made.