Bill Bryson - A short history of nearly everything

Some experts think they weren’t animals at all, but more like plants or fungi. The distinctions between plant and animal are not always clear even now. The modern sponge spends its life fixed to a single spot and has no eyes or brain or beating heart, and yet is an animal. “When we go back to the Precambrian the differences between plants and animals were probably even less clear,” says Fortey. “There isn’t any rule that says you have to be demonstrably one or the other.”

Nor is it agreed that the Ediacaran organisms are in any way ancestral to anything alive today (except possibly some jellyfish). Many authorities see them as a kind of failed experiment, a stab at complexity that didn’t take, possibly because the sluggish Ediacaran organisms were devoured or outcompeted by the lither and more sophisticated animals of the Cambrian period.

“There is nothing closely similar alive today,” Fortey has written. “They are difficult to interpret as any kind of ancestors of what was to follow.”

The feeling was that ultimately they weren’t terribly important to the development of life on Earth. Many authorities believe that there was a mass extermination at the Precambrian-Cambrian boundary and that all the Ediacaran creatures (except the uncertain jellyfish) failed to move on to the next phase. The real business of complex life, in other words, started with the Cambrian explosion. That’s how Gould saw it in any case.

As for the revisions of the Burgess Shale fossils, almost at once people began to question the interpretations and, in particular, Gould’s interpretation of the interpretations. “From the first there were a number of scientists who doubted the account that Steve Gould had presented, however much they admired the manner of its delivery,” Fortey wrote in Life . That is putting it mildly.

“If only Stephen Gould could think as clearly as he writes!” barked the Oxford academic Richard Dawkins in the opening line of a review (in the London Sunday Telegraph ) of Wonderful Life . Dawkins acknowledged that the book was “unputdownable” and a “literary tour-de-force,” but accused Gould of engaging in a “grandiloquent and near-disingenuous” misrepresentation of the facts by suggesting that the Burgess revisions had stunned the paleontological community. “The view that he is attacking-that evolution marches inexorably toward a pinnacle such as man-has not been believed for 50 years,” Dawkins fumed.

And yet that was exactly the conclusion to which many general reviewers were drawn. One, writing in the New York Times Book Review , cheerfully suggested that as a result of Gould’s book scientists “have been throwing out some preconceptions that they had not examined for generations. They are, reluctantly or enthusiastically, accepting the idea that humans are as much an accident of nature as a product of orderly development.”

But the real heat directed at Gould arose from the belief that many of his conclusions were simply mistaken or carelessly inflated. Writing in the journal Evolution , Dawkins attacked Gould’s assertions that “evolution in the Cambrian was a different kind of process from today” and expressed exasperation at Gould’s repeated suggestions that “the Cambrian was a period of evolutionary ‘experiment,’ evolutionary ‘trial and error,’ evolutionary ‘false starts.’ . . . It was the fertile time when all the great ‘fundamental body plans’ were invented. Nowadays, evolution just tinkers with old body plans. Back in the Cambrian, new phyla and new classes arose. Nowadays we only get new species!”

Noting how often this idea-that there are no new body plans-is picked up, Dawkins says: “It is as though a gardener looked at an oak tree and remarked, wonderingly: ‘Isn’t it strange that no major new boughs have appeared on this tree for many years? These days, all the new growth appears to be at the twig level.’ ”

“It was a strange time,” Fortey says now, “especially when you reflected that this was all about something that happened five hundred million years ago, but feelings really did run quite high. I joked in one of my books that I felt as if I ought to put a safety helmet on before writing about the Cambrian period, but it did actually feel a bit like that.”

Strangest of all was the response of one of the heroes of Wonderful Life , Simon Conway Morris, who startled many in the paleontological community by rounding abruptly on Gould in a book of his own, The Crucible of Creation . The book treated Gould “with contempt, even loathing,” in Fortey’s words. “I have never encountered such spleen in a book by a professional,” Fortey wrote later. “The casual reader of The Crucible of Creation , unaware of the history, would never gather that the author’s views had once been close to (if not actually shared with) Gould’s.”

When I asked Fortey about it, he said: “Well, it was very strange, quite shocking really, because Gould’s portrayal of him had been so flattering. I could only assume that Simon was embarrassed. You know, science changes but books are permanent, and I suppose he regretted being so irremediably associated with views that he no longer altogether held. There was all that stuff about ‘oh fuck, another phylum’ and I expect he regretted being famous for that.”

What happened was that the early Cambrian fossils began to undergo a period of critical reappraisal. Fortey and Derek Briggs-one of the other principals in Gould’s book-used a method known as cladistics to compare the various Burgess fossils. In simple terms, cladistics consists of organizing organisms on the basis of shared features. Fortey gives as an example the idea of comparing a shrew and an elephant. If you considered the elephant’s large size and striking trunk you might conclude that it could have little in common with a tiny, sniffing shrew. But if you compared both of them with a lizard, you would see that the elephant and shrew were in fact built to much the same plan. In essence, what Fortey is saying is that Gould saw elephants and shrews where they saw mammals. The Burgess creatures, they believed, weren’t as strange and various as they appeared at first sight. “They were often no stranger than trilobites,” Fortey says now. “It is just that we have had a century or so to get used to trilobites. Familiarity, you know, breeds familiarity.”

This wasn’t, I should note, because of sloppiness or inattention. Interpreting the forms and relationships of ancient animals on the basis of often distorted and fragmentary evidence is clearly a tricky business. Edward O. Wilson has noted that if you took selected species of modern insects and presented them as Burgess-style fossils nobody would ever guess that they were all from the same phylum, so different are their body plans. Also instrumental in helping revisions were the discoveries of two further early Cambrian sites, one in Greenland and one in China, plus more scattered finds, which between them yielded many additional and often better specimens.

The upshot is that the Burgess fossils were found to be not so different after all. Hallucigenia , it turned out, had been reconstructed upside down. Its stilt-like legs were actually spikes along its back. Peytoia , the weird creature that looked like a pineapple slice, was found to be not a distinct creature but merely part of a larger animal called Anomalocaris . Many of the Burgess specimens have now been assigned to living phyla-just where Walcott put them in the first place. Hallucigenia and some others are thought to be related to Onychophora, a group of caterpillar-like animals. Others have been reclassified as precursors of the modern annelids. In fact, says Fortey, “there are relatively few Cambrian designs that are wholly novel. More often they turn out to be just interesting elaborations of well-established designs.” As he wrote in his book Life : “None was as strange as a present day barnacle, nor as grotesque as a queen termite.”