I recently read, somewhat belatedly, Endless Forms Most Beautiful by evolutionary developmental biology pioneer Sean B. Carroll (the title derives from a line in On the Origin of Species: “from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved”).
This well-written book provides an excellent explanation for how a toolkit of genes like the Hox genes (see image below) control embryonic development in animals. The discovery of these genes shows that fruit flies, starfish, and people are more closely related than was once believed.
These genes work by producing proteins which in turn control the expression of other genes, in what is effectively a kind of computer program that can be visualised (and Endless Forms Most Beautiful contains several lovely colour plates which confirm this).
Photo: Caitlin Sedwick (from this paper)
Carroll concludes with a plea for teaching more evolutionary biology in schools. Personally, I think a greater priority would be an increased emphasis on teaching ecology, given the serious consequences which human activities (even well-meaning ones) can have for the planet. However, that quibble does not stop me from recommending this book to anyone who has not read it yet.