Frank Ryan, |
The Mystery of Metamorphosis: A Scientific Detective Story
(Chelsea Green, 2011)
In retrospect, bringing The Mystery of Metamorphosis on vacation wasn't a brilliant idea. While it is accessible to non-science readers like me, it's still not exactly fluffy. (Trying to pay full attention while slapping away mosquitoes probably meant that I missed some of the finer points.)
That said, author Frank Ryan takes us a fascinating journey into one of the strangest phenomena in biology: metamorphosis. Since I didn't know much about the subject, I loved the opening chapters describing just how weird and unintuitive the process is. Caterpillars don't slowly morph into butterflies inside their chrysalises; they sort of turn into a primordial goo from which a completely new animal is assembled. One quirky sea star, the Luidia, starts off as a swimming, bilaterally symmetrical larva. The radial adult form grows within its tissues and emerges to become an independent organism with a completely different body plan and life cycle. In other animals, the adult form devours or discards the larva's organs. And in still other animals, including octopuses, no metamorphosis takes place at all.
You don't have to be an evolutionary biologist to wonder how metamorphosis can possibly fit into the traditional Darwinian model of gradual change and adaptation over generations. The Mystery of Metamorphosis explores British planktologist Don Williamson's controversial theory that metamorphosis could be the result of long-ago hybridizations between completely different species. Although solid molecular evidence has yet to be found, Ryan lays out Williamson's experiments and results, and builds up, if nothing else, a persuasive argument for further investigation.
I found the second part of the book, which deals with the mechanisms of metamorphosis and their triggers, less interesting. It's all about the process of scientific testing and discovery, specifically the appropriately named Vincent Wigglesworth's Frankenstein-ish experiments on insects. (My ears did perk up when I learned that our resulting knowledge of juvenile hormone could be applied towards mosquito control.) In later parts of the book, Ryan goes on to look briefly at amphibians, the Cambrian explosion and even human development in the light of metamorphosis through hybridization.
The Mystery of Metamorphosis is not always an easy read, but it is chock full of new ideas to think about -- some of them still in development and with the potential to seriously shake up evolutionary science as we know it.
book review by
22 October 2011
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