A popular-level book covering two evolutionary events: water to land by tetrapods, and land to water by whales. The first half covers the same transition as Gaining Ground, but in much less technical language; you don’t have to know the ectopterygoid from the quadratojugal. On the other hand, the lack of technical precision can be misleading; lay people don’t like it when scientists use a lot of qualifications when describing things. An example is the Devonian animal Elginerpeton; in At the Water’s Edge this is “the oldest tetrapod known”, and author Carl Zimmer shows it as such on a neat little cladogram. In fact, all that’s known of the animal is the lower jaw, the proximal parts of two legs/fins, part of one shoulder, and some miscellaneous odd bits. There isn’t really enough to decide if it’s a “tetrapod” or a “fish” – which, of course, is the whole point of “transition fossils”; you really can’t put them in a nice Linnaean taxonomic pigeonhole.


Zimmer goes to considerable length to explain homeotic genes and why they are important in evolution – it’s a fairly clear explanation of a complicated subject. He allows himself to speculate on what the early tetrapods were doing with their legs, dismissing the possibility that they were walking on land with them. He also, a befits somebody who’s a journalist (albeit a technical one), goes into quite a bit of detail on the personalities of people in the Devonian vertebrate business. Thus we learn about the lives of Jenny Clack, Per Ahlberg, and Gunnar Save-Söderbergh.


The second half deals with the opposite transition; land to water, as in whales. This particular sequence has always been a favorite with Creationists, because for a long time there wasn’t very much in the way of transitional fossils. The relatively recent discovery of Pakicetus and Ambulocetus finally provide some. Maybe. The “maybe” here is that paleontologists have always thought the ancestors of whales were an interesting mammalian group, the mesonychids (one of the reasons mesonychids are interesting because they have carnivore-type jaws but hooves), while molecular geneticists find whales most closely related to artiodactyls, specifically hippopotami. Zimmer sides with the mesonychids, even while some of the paleontologists have now reversed their positions, and now go with the artiodactyls. The jury is still out, I think; the teeth of early whales, the archeocetes, look an awful lot like mesonychid teeth and there’s a few dubious things about molecular genetics.


Thus this is a interesting book but just may be dated; that’s the trouble with science. It’s a good read nevertheless. ( )

Too much about the history of the investigations, including all the dead ends of thought, biographies of the authors of discredited theories, and so too confusing for me.  All I want is a focus on the science, not a story.  Tell me what has been figured out.  Of course, given that this references work that is going on two (at least) decades old and is an active field of study, I'm better off looking for something newer anyway.

This was a man's first book? Now that's impressive. However, this is most decidedly not for the layman, a lesson the author learned because his books that followed are much more readable. He's brave too, selecting as a salvo the one topic most murky with incompleteness and conjecture. It's as if he was saying with his endeavor: "Here's a subject with the most gaps in the field. I'll start with this, write several more interesting books, and see where we stand after I establish an interesting career." It's quite possible he could soon offer a followup version that is more fossil-y complete. After all, there are dozens more dinosaurs roaming the earth now than there were when I was a child. ( )

Fabulous. This explication of macroevolution is dense but very clear. There are passages that simply sing. Zimmer is getting to be one of my very favorite science writers. If you have any interest in cetaceans, you should read this book. Highly recommended.

Here's a bit I loved:
"The seeds of a more surprising redemption of some of Haeckel's ideas came from the work of a mathematician named Alan Turing. Scientists who live on the harsh, lifeless plains of the physical sciences sometimes look at biology as a vacation spot - a lush green island they can visit, make a few groundbreaking discoveries, then head back to the quantum steppes. After all, they say to themselves, if you know the laws of electrons and protons, if you can solve differential equations, you already know how Life works. Most of these scientists barely get off the plane before they discover that they were wrong - that biology's island paradise is a sweet-smelling swamp - and they either sink out of sight or catch the next flight out. But a few, such as Alan Turing, have managed to discover some original biological principles." ( )

The author doesn't disappoint, but delivers his usual high quality explanation of the evolution of species. ( )