Customer Reviews

At the Water's Edge : Fish with Fingers, Whales with Legs, and How Life Came Ashore but Then Went Back to Sea

5 star:		(11)
4 star:		(6)
3 star:		(1)
2 star:		(0)
1 star:		(0)

 

 

Carl Zimmer brings the organizational skills of an experienced journalist and surprising literary talents to present an exquisite, up to date, narrative on the evolution of tetrapods, emerging from the water as amphibians and returning as cetaceans. In this book, he reports on the latest fossil discoveries, the prominent scientific researchers and the direction of their scientific analysis with style, and more importantly, great clarity. Some portions of At the Water's Edge are not easy for armchair paleo-buffs to comprehend, but Zimmer does an admirable job explaining the function of mesenchyme cells and hox genes. What I enjoyed most about this book, was the way Zimmer follows the trail of scientific discovery, documenting every bit of evidence, like a well-tuned detective novel. It's a compelling tale of interaction between paleontologist, geneticists, geologists and embryologists over many years. New fossil specimens demand a reworking of the evolutionary chronology. Our knowledge about the origins of tetrapods, our ancestral forbearers, is enhanced through the process of discovery. What I enjoyed most about Zimmer's work is the sense of objectivity and balance that comes from the third party perspective of a journalist. While Gould, Eldredge, Conway-Morris, Fortey and Bakker provide paleophiles books of great personal insight and passion, At the Water's Edge is completely satisfying in it's precise reportage. This is Zimmer's first book... I hope he's started another!

This book deals with two of the greatest transformations in natural history. The first part deals with how fish developed their body to live on land and the second explains how some mammals changed to go back and live in the water. The author explains how evolution, both micro and macro, works and gives us a tiny history of how Darwin's idea of natural selection changed how we thought about life on Earth.
The book not only tosses in a few new ideas, like early fish might of had both gills AND lungs, but but also shows how paletontolgy, ecology, genetics and embryology are being used to solve the secrets of macroevilution that biologists have been trying to uncover for centuries.
Carl Zimmer knows his stuff and knows how to explain it without confusing the readers.

It is unusual to describe a biology text as a real "page-turner", but Zimmer's book comes very close. It is an engrossing account of two of evolution's greatest transitions - from the water to the sea, and then, for some species, back to the sea once again.

The key to the success of this book is Zimmer's habit of taking the reader along on the dig. We follow Owen Gingerich to Pakistan and Egypt, where he finds hundreds of gargantuan whale-like Basilosaurus fossils in Zeuglodon Valley, and further discovers that they posess a very surprising feature - tiny little legs.

Follow Deaschler andd Rowe as they dig for tetrapod fossils, and discover a surprising number of fingers. Even when discussing such heady concepts as Hox genes and Sonic enzymes, Zimmer remains highly readable and entertaining.

The true test of a book lies in how it affects your outlook on life. In this case, I found myself keenly interested in the critters that inhabit our planet alongside us. With the hindsight afforded by a book such as this, we can see that the pattern of evolution is broadly stamped upon all of Nature's children.

I love Carl Zimmer's writing style, and thought Parasite Rex was excellent, and had this book recommended to me. Zimmer does a very good job at breaking down scientific processes and theories into layman's terms. I found the tetrapod evolution portion of the book most fascinating, and learned the most from this first half of the book. While the second half of the book is good, and cetacean evolution is interesting, my only problem with it was that some of it is a bit outdated. While I cannot blame Zimmer for this, as genetic and paleo breakthroughs are going on all the time, I would like to see an update of this section of the book, as many of the theories behind cetacean evolution have changed since this book was published. If you like Zimmer's stuff, or just are interested in science, Parasite Rex is a must read!

I'm not one to pen lengthy reviews as the idea is, after all, what is the book about, did I or did I not like it and why - plain and simple. Well, I did like it, hence the 4 stars. However, I'm not quite sure why. Mr. Zimmer explains about evolution, some exploring, discovering, insight and mystery solving in a style that contributes to it all being easily understood (almost as if you were involved with it in some small way). It's inspiring, informative and educational. It isn't a cliff hanger, but it kept my attention and after having put it down I wanted to pick it up again. Not riveting but, I think, addictive. If you're interested in discovering the linear progression of how our understanding has arrived at where we now find ourselves (regarding evolution) then give it a try.

I didn't expect this to contain so much history. Of course, the history of how these discoveries were made give a lot of insight but I was expecting more story-telling. I wanted to read more about the animals lives during their transitions (not in a fictitious way). Keep in mind, Carl Zimmer is a journalist, this book is extremely wordy. I would recommend Neil Shubin's "Your Inner Fish." Inner Fish is more up to date, shorter, and Shubin does an excellent job detailing short and simply. Zimmer actually mentions Shubin in this book.

At The Water's Edge is about about the evolution of large and important changes in species; Zimmer focuses on change in habitat, the move from sea to land, and then back to sea.

Zimmer begins by describing different fish lineages and concentrates on the branch that leads to our own chordate subphylum, the tetrapods. How and why did legs evolve? How did our left and right walking motion appear? Zimmer reveals a surprising answer. Tetrapods, legs, and walking did not evolve to help fish survive on land; they evolved to help fish swim in shallow swampy river deltas at the ocean's edge. These features allow fish to move more efficiently among the river plants and to sneak up on prey more easily. Once the left right motion was established, it was easy for fins to strengthen. At some point there came a need to move from puddle to puddle, or perhaps to escape predators, or to lie in wait out of the water. Strong alternating fins, which had evolved in a purely aquatic environment, were ideally suited to these new tasks.

To emphasize this original unplanned use of an existing feature, Zimmer uses Stephen Jay Gould's strange neologism "exaptation" rather than a more familiar term like pre-adaption. Zimmer prefers exaptation because pre-adaptation somehow implies that the final use of a thing was planned from the beginning. Zimmer emphasizes that it was not.

Once he's done with how tetrapods appeared and then came to land, Zimmer makes an about face and returns to the seafollowing whales and dolphins. Here too we find surprises. Early whale ancestors probably behaved like crocodiles and alligators. They would stay in the water with only their eyes and nose protruding, waiting for a land based prey to come close. Later, Zimmer describes echolocation, one of the most complex and useful features of cetaceans. Dolphins and many whales have a superb sonar system that works by echoing clicks out and back in through a fat-filled cavity in their forehead called the melon. The melon
acts as a sound lends letting dolphins "see" small objects hundreds of feet away. How can such a useful and complex organ evolve? The current hypothesis is that the melon's first function in early whales was simply to block the nasal passage during deep dives, to keep water out. Once it existed, it probably provided very rudimentary echolocation which gave natural selection something to work with. Another exaptation.

Another topic Zimmer touches often is cladism, which is the sorting of species into a genealogical table by identifying key features. Features common to a group of species can imply a common ancestor even if we haven't found any trace of the ancestor itself. Two cladistic schools are at this moment fighting it out: the biological and morphological school one side, and the genetic school on the other. The schools often arrive at different conclusions. The strength of the biological school is that its discoveries are practical; key features mean something concrete like a backbone (chordates) or a melon (dolphins and many whales). However, key features are very difficult to identify. Genes on the other hand are easy to identify and to compare among different species. Also, there's a mechanical logic to genes that readily lends itself to cladistic sorting. However, genes often don't mean anything, i.e. have no effect on how the organism works, and they can mutate at random, appearing and disappearing for no reason. Each camp will probably have to find a way to learn from the other.

Charles Darwin famously called his Origin of Species "one long argument", by which he sought to establish Natural Selection as the main means of evolution. You might take Zimmer's book as one short argument to establish exaptations and cladism as the main engines of macroevolution.

It is now 2009 and Zimmers book came out in 1998. Since it pulication Jennifer Clack's Gaining Ground, The Origin and Evolution of Tetrapods came out in 2002, Neil Shubin and others discovered Tiktaalik and he wrote Your Inner Fish about the transition from fin to limb. New fossils are being discovered in the emergence of whales from Mesonychids; limb to fin. Yes it's been an eventful eleven years in understanding the evolution of tetrapods, but for me the clearest presentation of the story of fin to limb and back is still a reread of "At the Water's Edge". When students or friends ask how these transitions occurred I still recommend this book for the claerity of it's presentation. Zimmer's book is still going strong.

This is one of my favourite books. Not just about whales, mind you, but about evolution of life in the oceans, then up onto land and, in some cases, back to sea again.

The author takes the reader through a complete yet understandable history of the evolution of whales. For my part, I knew that whales had once been terrestrial, but I didn't know even a tenth of the entire story. I learned that one of the first whales (or al least it's ancestor) was ambulocetus natans, a curious looking fellow who was something of a cross between a wolf and a whale. Then, on to Rodocetus and Basilosaurus and Dorudon, thogh not necessarily in that order.

I found out things I would never have expected in this book, such as the evolution of hand and how Hox genes work during development in the womb.

For anyone who is interested in whale evolution, human evolution, or life in the sea, this book is for you!

Anyone roughly familiar with the course of evolution knows that somehow, somewhen, some animals emerged from the sea. They became land animals - a lineage of them became us. Yet, looking at life in the sea, the emergence of life on land seems rather narrowly focussed. In the sea there are ten-armed squid, eight-armed octopi and five-legged starfish. Except for insects and spiders, nearly all land life from tiny shrews to the immense dinosaurs are formed on a consistent pattern. We're all four-limbed - we're tetrapods. How did that come about?

In this excellent synopsis of the life in the ancient seas, Carl Zimmer examines not only the animals living there, but the wide variety of environments the sea offers. Where, he asks, would life have found the most advantages? If you have some knowledge of physical limitations about salinity, pressure at depth and vision, the answer seems easy. If you don't, Zimmer carefully explains about the need for sunlight, limited pressure tolerance and available food. This location turns out to be in the shallow zones close to land. The shallow areas of the sea are the tidal zones, and it was there that a particular form of fish achieved particular success. These creatures - the lobe-finned fishes - had capability in changing environments. They may not have flashed through the water like marlin or tuna, but they could manuever when the tide fell. The lobe fin was comprised of a set of bones ending in five final extremeties. Examined closely, they look like a misshapen hand - or paw. And there's always four of them.

These creatures, cumbersome in appearance, still managed to make the transition to a dry environment. There were more than just klutzy-looking paws involved. Zimmer explains how the issues of breathing, digestion, body covering and other factors would all need adjustment to the land environment. Zimmer labels these changes "macroevolution". He uses the term to show how body elements changing required interaction among several areas to become a successful organism adapted to a new realm. Jawbones open or merge, skulls lengthen or grow wide, legs shift in position. And teeth? Ah, there's the real pointer to what land animals modified to survive.

Just when Zimmer has his subjects firmly established in forest and veldt, he must follow some of them back to the sea. The giant sea creatures known as cetaceans were a mystery even prior to Darwin's time. Darwin himself, perplexed by what mechanism could have brought these immense mammals back to their remote origins, offered one solution. Zimmer relates Darwin's idea that a swimming bear-like creature made the transition. Both Darwin and Zimmer acknowledge how unlikely that scenario is. What did take place, however, was unknown for over a century. After numerous false pointers, the precursors of whales turned out to be a low-slung wolf-like animal from what is now Pakistan. Phil Gingerich, scrambling about streamside cliffs in that country, produce Pakicetus. Ears and teeth became the focal point of research in early whales. The change from atmospheric to water hearing, including the trick of echolocation, traces how land animals returned to the sea. Changes in diet are reflected in how teeth are shaped and distributed.

Zimmer's account is a lively read, with good accounts of the paleontology and assessment of evidence. There are excellent line drawings to illustrate the various creatures discussed. As a science writer of excellent reputation, he graces the text with good footnotes and references, tucked away at the back. A fine study in a dynamic field. [stephen a. haines - Ottawa, Canada]

* with thanks and humble apologies to Steve Jones