Reading shapes
Evolutionary biologists have long held up songbirds, particularly the Galapagos finches first described by Charles Darwin, as an example of natural selection at work. In order to exploit different environments and food sources, the birds developed a startling variety of beak shapes — from short, blunt beaks ideal for cracking seeds and nuts to long, slender beaks designed to sip nectar from flowers. The assumption was that natural selection was the primary, if not the sole, cause for the variation. But while that variation can be tied, in part, to the way the beaks develop, Harvard researchers say that common developmental mechanism is also a powerful constraint on new beak shapes. A team led by Arkhat Abzhanov, an associate professor of organismic and evolutionary biology and a Grass Fellow with the Radcliffe Institute, and Michael P. Brenner, the Glover Professor of Applied Mathematics and Applied Physics and a professor of physics, has...