Seeing evolution through unblinking eyes
Philip MacCann
TRILOBITE!: EYEWITNESS TO EVOLUTION by Richard Fortey HaiperCollins, £15.99, pp. 269 Wordsworth once attacked geologists for being boring. But 200 years later Richard Fortey wreaked revenge in his geo- logical history of Britain, The Hidden Land- scape. He descended upon Wordsworth's woeful lines and pitted against them his own poetic vision — an unlikely one formed by his work in palaeontology.
That this science deserves a special place in our souls is one theme running through all of Fortey's highly focussed books. The origin of species is much earlier than previ- ously thought, and our mounting knowl- edge about human evolution links us ever more meaningfully to vanished worlds. Once life was up and running in the form of methane-brewing archaebacteria, detailed records began to be taken and have been preserved for us untouched from Pre-Cambrian days. Vivid snapshots of the earliest evolution survive, revealing details 'more delicate than lace and as fugitive as a cobweb' — a startling metaphor for fossils.
In Fortey's Life: An Unauthorised Biogra- phy he recounted the entire story of 3,800 million years of evolution, as the rocks tell it — what he called the 'narrative in stone'. This epic tale blended scientific authority with poetic vision — of the land, evoked by big palpable words, and of time. A dividing cell is suddenly buried by sediment and so endures 850 million years — two extremes of time yoked together in the image of the fossil. It's hard to return to Wordsworth.
But let's face it, the limits of fossils were reached here, the remotest boundaries of palaeontology fine-combed for human interest, blood was squeezed out of stones. Life had an unsatisfactory gap at the great- est moment ever — the formation and con- tribution of self-replicating molecules — because this is properly a moment for an evolutionary biologist: DNA just doesn't fossilise.
'My last book was a biography of all life from bacterium to mankind in which the trilobites were passed over in a page or two,' Fortey now writes, spotting a surpris- ingly different gap. 'Now I have the chance to turn the focus the other way and allow my favourite animals to tell their stories in the detail they deserve.' So this is not sim- ply another attempt to describe everything through fossils, but this time through fossils of trilobites!
Most closely related to the living horse- shoe crab, Limulus, and roughly resembling woodlice, trilobites swam in the Palaeozoic oceans for some 350 million years, becom- ing extinct over 200 million years ago (50 million before the dinosaurs). If ours is the age of insects (70 per cent of all species are insects), the early Palaeozoic was the age of trilobites. Fortey has coined names for many of their thousands of forms, be they spiky, smooth, blind, bug-eyed. In many, compound crystal eyes were the first use of optics coupled with sensory perception in nature and it is a mystery why this design was jettisoned.
Being so common and preserving well because of their calcite exoskeleton, this oldest fossil arthropod carries vastly more information than the rare remains of more spectacular creatures. The presence of identical species in rocks of identical age at locations now separated by oceans tells of the drift of continents, and trilobites have helped geologists design an Ordovician map. They have cast light on how species are generated and provide evidence sug- gesting that the theory of a Cambrian explosion of life may be mistaken. Most intriguing, trilobites could silence creation- ists for ever since they show evolution in action, seamless transitions between one species and another — the famously antici- pated 'missing links'.
Because Trilobite! is an uncompromising expedition, Fortey entertains us with his poetic gift and much defensive hyperbole. 'The magical trilobites' are 'fascinating', 'enigmatic'. These much-misunderstood 'poor things' are 'dramatic' too. 'What a wonder!' Think of the nutty enthusiasm of an erudite collector of Edwardian settees anxious to convince us how deeply they matter. This is not a scientific contribution like that by Euan Clarkson, R. C. Moore, or the precise and illuminating essay by Riccardo Levi-Setti (a nuclear physicist who photographs trilobites as a hobby). Instead, it soars at its most subjective, like a fanatical diary: 'Pushed half of Europe across half an Atlantic. . . closed ancient seaways and opened up others. . . To do this, I have used trilobites.'
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