From geology to mould, the naturalist's publications form a coherent whole, finds Eugenie Scott.
The Darwin Archipelago: The Naturalists's Career Beyond Origin of Species
Most people are familiar with On the Origin of Species, but few are aware of Charles Darwin's decades of productive work before and after its publication. Indeed, creationists present Darwin as a one-trick pony: a rich dilettante who loafed around his country manor until he stumbled across evolution by natural selection. So I was delighted to read Steve Jones's The Darwin Archipelago (published in Britain as Darwin's Island), an entertaining and thoughtful treatment of Darwin's other books.
Darwin was a respected scientist — and a recipient of the Wollaston Medal, the Geological Society of London's highest award — well before the Origin's publication in 1859. By then, he had eight books to his name, starting with The Voyage of the Beagle in 1839 and followed by three volumes on geology and four on barnacles. Ten further books and monographs appeared after the Origin, including The Formation of Vegetable Mould, through the Action of Worms, which was published in 1881, the year before his death at the age of 72.
As in his earlier treatment of the Origin, titled Almost Like a Whale (published in the United States as Darwin's Ghost), Jones shows how Darwin's ideas have inspired and been augmented by subsequent research. And Jones shows his flair for a one-liner: a worm is an “animated intestine”, and molecular biology is “no more than comparative anatomy plus a mountain of cash”.
Jones notes that all of Darwin's work supports the principle that, driven by natural selection, small changes “given time, can produce gigantic ends”. Anatomy, behaviour, biogeography, embryology — so many characteristics of organisms can be explained by selection on precursors that gave some advantage to their possessors. The peculiar “contrivances” of insectivorous plants to attract and capture prey, for example, can be explained only by natural selection.
An 1881 Punch cartoon satirizing Charles Darwin's body of work that connected humans with worms.
Darwin's works also show what his contemporary William Whewell referred to as “consilience”: the confluence of evidence from a variety of sources. As Jones puts it: “The great naturalist's lifelong labours generated an archipelago of information; a set of connected observations that together form a harmonious whole.”
Time and again, Jones's book caused me to reflect on how delighted Darwin would have been to have had some titbit of evidence discovered after his death — such as the fossilized bee found with a pollen sac attached, which sheds light on the evolution of plants, or the discovery of genes for olfaction in mice. This latter finding supplements Darwin's observations of the importance of urine marking in mice for choosing a mate and avoiding inbreeding.
The last chapter is depressing but important. Introduced plant and animal species sometimes spread at the expense of natives, reducing diversity, Jones notes. Similarly, our own species has become less diverse: as our ability to manipulate the environment has grown, the variance in human death rates and birth rates has fallen, and variation within and between populations has declined because of migration and intermixing. Yet this variation is the key to adaptation by natural selection.
What does this say for the future? We know that environmental pressures will require adaptation. “One day, [Darwin's] machine will take its revenge,” Jones warns. “We may well fail in the struggle for existence against ourselves, the biggest ecological challenge of all.” Natural selection bats last.