There lived a happy Coelacanth
In dim, primordial seas;
He ate and mated, hunted, slept,
Completely at his ease.
Dame Nature urged: ‘Evolve!’
He said: ‘Excuse me, Ma’am,
You get on with making Darwin,
I’m staying as I am.’
Horace Shipp’s little hymn to the ‘living fossil’ fish-with-legs — thought long extinct then astonishingly discovered in a South African fish market in the 1930s — gets the evolutionary process upside down, of course. Evolution is not something that a fish, or a dame, wills; it just happens. Nonetheless, the poem captures the curiosity of the fact that, while some lineages change dramatically over time, others do not.
Set the sat-nav on your time machine to the Carboniferous, 300 million years ago, and you would land in an alien world. No grass, no flowers, no birds or mammals, no frogs or snakes, no ants or flies. Yet among the unrecognisable life forms, a few creatures would instantly be familiar from living examples on today’s earth: horseshoe crabs, velvet worms, scorpions, lampreys, lungfish, ammonites, cycad trees, horsetail ferns.
It is these ‘survivors’ that Richard Fortey has set out to visit in their haunts, a task that takes him — poor chap — all over the world to wander among beaches, forests, deserts and swamps. One moment he is marvelling at prelapsarian ‘stromatolites’ in Shark Bay, western Australia — pillow-shaped structures in shallow salty water built by thin films of microbes and a type of life that existed two billion years ago; the next he is at a Buddhist shrine in China, visiting the only wild specimens of the gingko tree, whose leaves, unchanged, are found as fossils from early in the time of the dinosaurs, 200 million years ago.
If you have not the time to follow in his footsteps, then take the armchair tour with Fortey as your genial and fascinating guide. As an expert on fossils, he brings a different perspective to living species. In the time since his favourite trilobites lived, whole mountain ranges have been ground away. Yet parts of the DNA sequence of a trilobite persist in at least partly recognisable form not only in their relatives, the horseshoe crabs, but in him and me. ‘Life outlasts even mountains, for the greatest survivor of all is DNA’.
This book would have been fun to read (and write) at any time during the past couple of hundred million years, but it is especially so at this moment. Until recently, we were dependent upon fossils for hints about the history of life. Now DNA provides a crib sheet, a compendious list of solutions to the puzzles. It’s as if we have stumbled on a four-hour television interview by a Dimbleby of both Julius Caesar and Vercingetorix.
Not that this takes away the mystery. It adds to it. The more we find out about the genes and bodies of these enduring species, the more questions we can ask. Why does the primitive flowering plant Amborella of New Caledonia have chunks from the genome of a moss in its cells, a startling fact I learned not from Fortey’s book, but a recent conference? Why does the duck-billed platypus have ten sex chromosomes? Why does it and the echidna have a venomous rear claw in males (venom being something mammals otherwise entirely lack — ‘with the exception of critics’, says Fortey sharply)?
Above all, how did the survivors do it? Just as something about centenarians enable them to get through ten decades without dying, so something about these survivor species enabled them to get through hundreds of millions of years without either going extinct or changing shape. Fascinatingly, Fortey finds that there appear to be ‘time havens’ — habitats and locations where clusters of survivor species can be found together. The tidal mudflats of a bay near Hong Kong reveal not only a brachiopod, but also a lancelet and a peanut worm that are little changed since the Paleozoic. A Chinese mountain range is full of survivor tree species; so is New Caledonia; an undersea marine plateau east of Queensland is home to several survivors, including the Nautilus, made to a design that dominated the oceans of the Mesozoic.
Survivor species tend to be long-lived, slow-growing, slow-breeding species. Welwitschia, a bizarre South African plant, lives for many decades, as do the lungfish and the tuatara, a primitive New Zealand creature that looks like a lizard but is actually descended from a very early form of reptile. These are species designed to run geological marathons. How glorious to live at a time when, thanks to Fortey’s fine prose, we can feel their peculiar longevity.
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