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Aqua Incognito

AQUAGENESIS: The Origin and Evolution of Life in the Sea, by Richard Ellis, Viking: 304 pp., $25.95

November 04, 2001|OSHA GRAY DAVIDSON and OSHA GRAY DAVIDSON | Osha Gray Davidson is the author of several books, including the forthcoming "Fire in the Turtle House: The Green Sea Turtle and the Fate of the Ocean."

When I was growing up in Iowa, my family would pile into the station wagon on sweltering summer days and head for Pella, a small town about an hour from our home in Des Moines. Pella hosts one of the nation's oldest tulip festivals, at which each year townspeople celebrate their Dutch heritage by donning traditional costumes, clunking around in wooden shoes and, not incidentally, raking in tourist guilders.

As a general rule, we were suckers for just this sort of kitsch, but our journeys to Pella had a different purpose. Our destination was actually a couple of miles from the carefully tended beds of variegated tulips, a place that couldn't have looked more different: an abandoned quarry, dotted with algae-choked pools, wedged between a garbage dump and a cornfield. That may not sound like much, but my brothers and I couldn't get enough of the place.

For there we experienced the astonishing reality that all parts of this planet were once ocean. The quarriers had stripped away the rich Iowa topsoil, exposing a network of ancient limestone outcroppings chock-full of fossilized marine life: corals, flower-like crinoids, fish skeletons and much else.

Here was the true field of dreams: Iowa was once a tropical ocean. Just about anything is possible, we realized, in a world where cornfields cloak ancient sea beds. If someone had told us that beneath the limestone were the remains of Atlantis, we would have begged our parents for dynamite and pickaxes and started burrowing deeper.

Nearly every fossil was a revelation. But it was the rare cry "Trilobite!" that brought us scrambling together to ooh and ahh over the half-inch specimens. The thrill was largely the result of the scarcity of trilobites at the Pella quarry.

But Richard Ellis' fascinating and important new book, "Aquagenesis," gives one a far greater appreciation for the ancient creature. Trilobites may have been rare around Pella but, as Ellis (a science writer and author of "The Search for the Giant Squid") points out, they were once the dominant animal life form on the planet.

There were at least 15,000 trilobite species, some nearly a yard long. They existed for an almost unimaginable 300 million years. And the trilobite was an evolutionary leap forward: Life's first grand experiment with a sensory system that would come to dominate the animal kingdom--eyes. The amazing trilobite is just one of many treats awaiting readers in Ellis' book.

There is also the creature known as Dickinsonia, long extinct, the size and shape of a beaver's tail, about which so little is known that scientists have, at different times, described it as a jellyfish, a coral, a worm, a bacterium or a creature from outer space.

Ellis also gives richly detailed descriptions of living marine animals ranging from those adored mammals, whales, to the more fearsome marine reptiles, crocodiles.

But I may be giving a false impression. What Ellis has done in "Aquagenesis" is something more ambitious than providing a bestiary of marine life (although that alone would be worth the book's price). Ellis adroitly limns scientific understanding of evolution at work in the sea--always a moving target. He places these magnificent creatures in their context of time and space, and examines the sometimes bitter scientific controversies they've bred. Remarkable in so many ways, this is what really sets Ellis' book apart from similar works on animal evolution.

With a few notable exceptions--Stephen Jay Gould's "Wonderful Life," for example--most popular books on the subject take as their starting point life's emergence from the global ocean onto land. These works may give a begrudging nod to our aquatic past, but life in the sea is ultimately aqua incognito: unknown, unknowable and, at any rate, a bit beside the point.

That's a startling oversight considering that the ocean not only makes up 99% of the world's living space but was also the only place where life existed on Earth for most of our planetary history. As Ellis approvingly quotes writer Philip Ball: "The story of life is ... a story of life at sea." And this is the story Ellis gives us, in great depth and full of richly entertaining details.

In the final chapter, Ellis takes up what is probably the most interesting and certainly the most controversial of the book's wide-ranging discussions: the theory that we are descendants of semi-aquatic apes. First articulated by marine biologist Sir Alister Hardy in 1960, the theory proposes that early hominids, though well-established on land, returned to a swampy coastal environment for a significantly long period--long enough to develop traits still with us that have no better explanation than an aquatic sojourn.

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