Dances with fruit flies
The fly, at first, looks like nothing so much as a tiny matador. Now standing still, now feinting left or darting right, he circles the petri dish arena, waving a black-tipped wing at his quarry like a red cape. But he's a lover, not a fighter, and his dance is intended to induce the fruit fly equivalent of a swoon. Scientists can no more explain why female Drosophila biarmipes flies go gaga for manly markings than they can determine what it is that attracts teenage girls to Ashton Kutcher. But the spots--unheard of in biarmipes' s cousin, the widely studied lab fly D. melanogaster --are helping to shed light on even more vexing questions of animal evolution. Among them: How can species with nearly identical DNA turn out as different as biarmipes is from melanogaster, or as humans are from chimpanzees?
We're living at a strange moment in America. Once again, evolution is becoming a controversial topic. But while school boards are revisiting the 19th-century debate over whether evolution even happens, 21st-century scientists are beginning to show exactly how the natural phenomenon works. Using the powerful tools of molecular biology and comparative genomics, they're finding specific changes in the DNA that can account for 17,000 species of butterfly or why insects have only six legs instead of a dozen. And while some 55 percent of Americans balk at the idea that humans evolved at all, analysis of the genes that build our bodies shows our clear kinship not just to the apes but all the way back to bugs, worms, and beyond. Along the way, scientists are starting to find concrete explanations for everything from our large brains to just exactly how the fruit fly--or the leopard, for that matter--got its spots.
User friendly. Sean Carroll, in whose University of Wisconsin-Madison laboratory the biarmipes flies danced, has been at the head of the new wave of evolutionary studies for two decades. An investigator with the Howard Hughes Medical Institute, Carroll sets out in his engaging new book, Endless Forms Most Beautiful (W. W. Norton), to introduce us to the field he helped found: evolutionary developmental biology, or "evo devo." Writing in a clear, straightforward style and drawing on his own love for wildlife (and classic rock) for inspiration, Carroll pulls together decades of work by hundreds of scientists. He reveals a remarkable series of insights into how evolution has shaped--and continues to shape--the wondrous assortment of creatures that share this planet with us. He emerges as the new, user-friendly public face of evolutionary science in the process.
Carroll wasn't particularly interested in bugs as a kid; growing up in Toledo, Ohio, in the 1960s, he was more of a snake guy. But laboratory science has its demands, and insects like the fruit flies--and later, butterflies--Carroll chose to study are much easier to work with than more impressive forms of wildlife. But there was a bigger problem. From Charles Darwin on, biologists suspected that the mysteries of evolution would be revealed in life's other great mystery--the development of tiny, simple fertilized egg cells into large, complex adults. "All changes in animal form come about through changes in development," Carroll says, "but we knew next to nothing about development when I started "graduate school in the late 1970s. "So I knew we would have to push the field forward first."
advertisement
