Word of the day: spandrel. It’s most commonly used in architecture. It’s the triangular space between the curve of an arch and its rectangular frame. But in biology, the same word describes evolutionary traits that are byproducts of other developments. Examples of spandrels in the human form include: Human facial structure. The overall shape of our faces (including reduction of the brow ridge) could be the result of brain expansion and smaller chewing muscles, among other cha

The Tree of Life—Solving Science’s Greatest Puzzle  will be published this November in the U.S. and it looks like a winner. (It’s been...