A Skeptic Warns: Nature's Not Simple


April 16, 1989|By Reviewed by Michael McLeod of The Sentinel Staff

Twenty years ago, everyone pretty much thought of dinosaurs as evolutionary nerds. They may have bullied their way around the Earth for a while, but in the end they were so ponderous and slow-witted that Mother Nature was all but forced to bench them. Dinosaurs, Leonard Krishtalka reminds us, once were considered ''a metaphor for the dumb and the defunct'' - born losers, the Edsels of the natural order.

Now, suddenly, dinosaurs are cool. They didn't die because they were stupid but because they ran into some bad luck and got killed off by a natural cataclysm. Could have happened to anybody. Besides, dinosaurs were actually lively, warmblooded creatures, not lazy reptilian thugs. And instead of skulking around in drab, pea-green skins, they may have been decked out in fashion-risk hides done up in the kind of garish Day-Glo tones reserved these days for subway art and skateboards.

At least, that's how some of the currently fashionable research about dinosaurs is being interpreted. But Krishtalka is suspicious. ''I am wary of simple theories,'' he writes in Dinosaur Plots & Other Intrigues in Natural History. ''They may have appeal, but one difference between nature and its interpreters is that nature is not simple.''

So Krishtalka, in this series of essays on natural phenomena, picks away consistently at easy answers. Maybe dinosaurs weren't wiped out in one fell swoop, as one researcher theorized, when an asteroid struck the Earth 65 million years ago. The theory sounds great, says Krishtalka - until you take a look at the dinosaur fossils that have been unearthed over the years.

Judging by the fossils, dinosaur species did not die out all at once but slowly, over hundreds of thousands of years. And the last few stragglers (somehow it's heartwarming to find out that those perennial sci-fi movie favorites, Tyrannosaurus and Triceratops, were among the last to go) date back to before the time of the supposed asteroid-Earth collision.

''Where is it written that dinosaurs disappeared in a sudden cataclysm of mass extinctions?'' asks Krishtalka. ''Not in the rocks.''

Krishtalka, a paleontologist with the Carnegie Museum in Pittsburgh, plays hardball when he thinks people have tried to oversimplify the natural order. But he is also playful enough to include the kind of questions that only a child could ask. In fact, one of the essays is based entirely on questions that children asked about dinosaurs after trips to the museum.

Some of the children's questions, and Krishtalka's answers, are humorous: ''Did dinosaurs live near Columbus, Ohio?''

''Not if they could help it,'' is Krishtalka's droll reply.

But some of those questions lead him into serious discussions. How, for example, did dinosaurs ''do it''? Yes, our children wonder about these things, as do naturalists. Krishtalka writes of research suggesting that dinosaurs, like most modern-day reptiles, had no external genitalia. They probably mated annually, the male fertilizing the female's eggs in a union that must have been a cumbersome and oddly delicate spectacle.

Krishtalka's wide-ranging wit isn't restricted to dinosaurs in these essays. He shows a penchant for gravitating toward all the hot spots of natural history, not just those that involve questions of how the thunder lizards made the earth move. So it's no surprise to find him wading into the ''creation science'' debate:

'' 'Creation science' - a fundamentalist, literal Genesis-reading of origins - should not be allowed to bully its way into science classes and texts under the flummery of fair play or the facade of science.''

Krishtalka is equally impatient with current theories suggesting that, given mutations in mitochondrial DNA, all of mankind can trace its ancestry to a single female who lived 200,000 years ago.

Too many assumptions, says Krishtalka. How do we know that DNA mutates at a regular rate? That only one woman carried that same DNA blueprint?

Like the good scientist that he is, Krishtalka is always impatient with simple answers, whatever their origin.

Orlando Sentinel Articles