
Carl Zimmer explains the evolutionary pressures of different ways of life in different ecologies in tracing the probable path of whales to the ocean, using the magnificent series of transitional fossils found in the 80s and 90s. Along the way he explains why whales and seals use their flippers differently, why fish can lose their eyes but octopodes don't, how many lineages of fish have lungs for use out in the open seas, and why the baleen whales developed from toothed whales. He also follows a whole series of transitional fish to four-legged creatures. He shows us how one change in the timing of an embryo's development can change a whole group of characteristics in the adult. And he makes it seem simple!

Incidentally, in describing two great macroevolutionary events, Carl Zimmer delineates some of the real controversies that have been going on in evolution: Did baleen whales descend separately from archaeocetes or did they develop from the toothed whales? Did lungs develop from swim bladders, as earlier scientists assumed, or was it the other way around? Is five digits a standard pattern or a mere byproduct of developmental patterns?
Labels: authors, books, ecology, evolution, physiology, science writing, scientific method, teach the controversy