Book Review : Chance in a Collision With Darwinism

The Great Dying by Kenneth J. Hsu (Harcourt Brace Jovanovich: $17.95)

The hypothesis that the Earth suffered a catastrophic collision with a giant cosmic body 65 million years ago has become one of the most seminal scientific ideas of recent years. It has spawned a tremendous amount of work by researchers in many disciplines, who have found corroborating evidence in rocks, in the oceans and in the atmosphere. Increasingly, scientists are forging links between this idea and other areas of work, which is a sign of a very powerful theory indeed.

Early on, this notion of global disaster stemming from a massive collision was applied to explaining the sudden disappearance of dinosaurs at the end of the Mesozoic Era. What happened to these creatures is a question that has stumped paleontologists since dinosaur fossils were first discovered.

Starting in 1980, when Luis and Walter Alvarez proposed this explanation, a growing number of researchers have amassed a growing body of data that supports it. While the exact mechanism and sequence of events remain a matter of dispute, a large number of scientists are now convinced that something of this nature has occurred not just once but repeatedly during the Earth’s 4.5-billion-year history.

Challenging Darwin

Kenneth J. Hsu, a distinguished Chinese-born geologist now working in Zurich, Switzerland, was slow to be persuaded by this theory, but he has now embraced it with a passion. What’s more, he finds in the story of periodic mass extinctions a fatal challenge to the Darwinian notion that evolution has proceeded through the “survival of the fittest.”

To be specific, Hsu argues that more-fit species do not do in less-fit species. Mammals were not more fit than dinosaurs, he says. Rather, the cosmic catastrophe of 65 million years ago made the Earth uninhabitable, and the dinosaurs all died off along with 75% of all species then alive on the planet. They were replaced by mammals, Hsu says, but the mammals did not compete with and win out over the dinosaurs.

“If most extinctions are caused by catastrophes,” Hsu writes, “then chance, not superiority, presides over who shall live and who shall die. Indeed, the whole course of evolution may be governed by chance, and not reflect at all the slow march from inferior to superior forms so beloved by Victorians, and so deeply embedded in Western thought.”

This last sentence displays one of Hsu’s subthemes, which is that we have embraced “survival of the fittest” because it coincides with our idea of progress and because it coincides with our idea that winners have superiority going for them. He doesn’t like either idea.

A ‘Wicked’ Ideology

“The law of natural selection is not . . . science,” Hsu says. “It is an ideology, and a wicked one, and it has as much interfered with our ability to perceive the history of life with clarity as it has interfered with our ability to see one another with tolerance.”

Now, Hsu may well be right that chance is as important to evolution as any other factor, but it is hard to dismiss the fossil record, which clearly shows the development of life from simpler organisms to more complex ones. And it is the more complex organisms that are better adapted to their environment and that exercise more control over it.

It is not just egocentrism that causes human beings to regard themselves as the most advanced animals on the planet. Much evidence supports this conclusion. For example, members of what other species are reading a newspaper at the moment? (Come to think of it, that may not be such a good example, but you get the idea.)

So Hsu’s argument does not show that Darwin’s idea of natural selection is wrong. It merely shows that natural selection may not be evolution’s only determinant. Other factors--even other important factors--may also be at work.

Common Ancestry

Nor does Hsu’s book argue against the central idea of evolution, which is that all life developed from a common ancestor. The evidence for this is overwhelming.

When Darwin proposed his theory in 1859, he had no idea of the mechanism of biological inheritance. Genes and their significance were discovered later, as was the role of DNA as the carrier of the genetic code. But everything that genetics and microbiology have learned in this century have supported Darwin to a T. It is one of the most extraordinary stories of verification in the history of science.

Oddly, most of Hsu’s book is not about what he announces as his topic. After laying out his thesis in the first chapter, he doesn’t really come back to it until the end. In between, he presents, discusses and analyzes the evidence in support of the comet-extinction theory of dinosaurs and other species, and he shows the role he has played in its development.

Accessible--and Flat

Unfortunately, though Hsu is a very good scientist, he is not a great popularizer. His prose, while accessible enough in most places, is decidedly flat. He does not convey the excitement of doing science or any of the interplay of personality that is part and parcel of the quest for knowledge.

Popular science should draw in readers who may not have even thought they were interested in the topic. Hsu’s book probably won’t do that, and it’s too bad, for the collision/mass-extinction theory is itself an intriguing yarn that has gone in a few years from improbable to very likely accurate.

How scientists have come to agree about this is an important and interesting story, as are those parts about which there remains disagreement. Hsu tends to write too narrowly about his material, which deserves a much more compelling treatment.

Only at the very end of the book, literally in the last few pages, does he open up and become more expansive. He would have written a better book if he had applied that approach throughout.