In recent decades, scientists have learned that life is governed by the extraordinary system of genes encoded in the chemical patterns of DNA in every cell. These mechanisms have gradually been revealed, and we now know how genes can be transmitted between generations, and how they are expressed in the bodies of all living things. This knowledge has accompanied an ever increasing understanding of the dynamics of evolution through natural selection, whereby different species ensure their survival and accommodate themselves to environmental changes. Today, as molecular biologists actively intervene in the genetic material of more and more species, and especially in view of advances in reproductive technology, our very perception of the meaning of life is subject to change. This encyclopedia provides an up-to-date, accessible, and attractive introduction to these important ideas. Its thematic organization, highlighted by full-color artwork and state-of-the-art photographs, takes the reader to the essence of the key topics in genetics and evolution, exploring recent discoveries and ongoing debates. The 500-entry keyword section provides a bonus "mini-encyclopedia" of central terms and concepts, while the unique factfiles present critical information in easy-to-read charts and graphs.