Evolving Metamorphosis: A Hopeless Task

In Current Biology last month,1 Jason M. Tennessen and Carl S. Thummel from the University of Utah School of Medicine had a lot to say about the complex dance of signaling partners -- hormones, receptors, organs, and genes -- that guide a fruit fly through its stages of life. It's pretty amazing stuff. How did it come to be? Well, the relevant subtopic in the article is titled, "An Evolutionarily Conserved Program to Coordinate Growth and Maturation."

Conservatism in evolution is...