The following essay was my contribution to the 2002 book Darwin Day Collection One: The Single Best Idea Ever, a collection of articles, reviews and cartoons in celebration of Darwin and science. It appeared as the final essay in the book. The title was inspired by Thomas Henry Huxley’s essay We Are All Scientists, which was the first essay in the book.
With over a decade’s hindsight, I wish I had been a bit more careful with my use of the word ‘theory’ in this essay. It is a word whose conflicting scientific and vernacular meanings cause considerable confusion. I deliberately chose not to elaborate on this difference. Most of the time in this essay, I use the word ‘theory’ in its scientific sense (i.e. an idea currently—or formerly—accepted by the vast majority of scientists working in that field as the best explanation we have for an observed phenomenon). But, in some places, I slip into the vernacular sense of the word (i.e. ‘just’ an idea that hasn’t really been tested yet—what a scientist would describe as a ‘hypothesis’). I should also probably have been more careful referring to ‘revolutionary’ ideas. The concept of sudden scientific ‘revolutions’ is one that is often (and rightly) criticised by science historians—even though referring to changes in thought retrospectively as ‘revolutionary’ still strikes this non-historian as useful shorthand.
Several years after I wrote this essay, snails finally began to establish themselves in my garden. I’m still trying to figure out why this might be.
In his brief autobiography, completed less than a year before his death, Charles Darwin, with typical modesty, claimed to have had “no great quickness of apprehension or wit which is so remarkable in some clever men”.
What’s this? The genius who came up with the most important theory in biology (a theory, indeed, without which, one other illustrious biologist is forever being quoted as having remarked, nothing in biology makes sense); the man who worked out how coral reefs form before he had even seen one; the man whose noble bearded visage now graces the back of the Bank of England’s £10 note; the man whose birthday we are urged to celebrate every February 12th: claiming that he wasn’t particularly quick in the brain department? False modesty, surely, Mr Darwin!
But, no, Darwin knew where his real talent lay:
On the favourable side of the balance, I think that I am superior to the common run of men in noticing things which easily escape attention, and in observing them carefully. My industry has been nearly as great as it could have been in the observation and collection of facts. What is far more important, my love of natural science has been steady and ardent.
Coming up with great theories, like other forms of invention, is typically 1% inspiration and 99% perspiration. It took Darwin a relatively short time following his return from his five-year voyage aboard HMS Beagle to piece together the basic ideas behind his theory of evolution by means of Natural Selection; he then spent the next 20 years amassing evidence in support of his theory before finally going to press. Indeed, it is debatable whether he would ever have published his theory during his lifetime, had he not been forced to do so to avoid being scooped by Alfred Russel Wallace.
Contrary to popular (and Darwin’s own) belief, most major scientific advances do not come about by the careful, impartial observation of facts, which are gradually pieced together to form new and better theories. In the real world, most of the fact-gathering associated with major new theories occurs after the event: facts are gathered to test the new theories that scientists have concocted (sometimes almost out of the blue) in an attempt to explain anomalies associated with existing theories. In a process somewhat analogous to Darwinian Natural Selection, if the new theories are fundamentally inadequate, they will soon be discredited by observation and experiment and will die a quick death. If, however, the new theories are more robust, they will survive the initial tests, and will become worthy of further investigation. As the new theories pass more and more tests (possibly with a little adaptive fine-tuning), scientists become more and more convinced that there might be something in them (although they can never say categorically that they are ‘true’). Science, to extend the evolutionary analogy (although perhaps too far for some people), tends to be characterised by short bursts of revolution (where major shifts in scientific thinking take place), punctuated by much longer periods of ‘normal science’ (where the accepted scientific theories of the day are tested, tinkered with, adapted, and generally fleshed-out).
So it was, albeit on a smaller, more personal scale, with Darwin’s life in science: yes, he devised the (r)evolutionary theory that still underpins all the biological sciences, but most of Darwin’s scientific life was spent carrying out good, occasionally brilliant, ‘normal science’ to test his theory.
So, how did Darwin carry out this normal science? How did he exercise his great industry in the observation and collection of facts?
Darwin gathered his information in three ways: by talking and corresponding with other people, by reading, and by making observations and experiments of his own. His letters (which are still being compiled and will eventually be published in their entirety in the magnificently researched Correspondence of Charles Darwin [Cambridge University Press]) make fascinating reading for anyone interested in seeing the mind of a genius at work. They are jam-packed with references to books, papers and periodicals, requests for information, ideas and opinions, and descriptions of experiments (either carried out by Darwin himself, or to be carried out by the letters’ recipients).
Darwin wrote to anyone he thought could help him with his research, from gardeners and pigeon fanciers to world-famous scientists and government representatives abroad. His requests for information ran from the mundane to the seriously weird. Here are just a few examples chosen at random from Darwin’s correspondence of 1857:
- [To P. H. Gosse] Can you tell me, you who have so watched all sea-creatures, whether male Crustaceans ever fight for the females[?]
- [To W. B. Tegetmeier] I wonder whether Fowls when crossed throw odd & unexpected colours like Pigeons do.—Do you know of any such facts? For instance if you were to cross black Spanish with Black or Silver Polands, do you suppose ever red or other marked new colour would appear?
- [To Alfred Russel Wallace] Can you tell me positively that Black Jaguars or Leopards are believed generally always to pair with Black? … Is the case of parrots fed on fat of fish turning colour, mentioned in your Travels?
- [To Gardeners’ Chronicle] Will any reader of Gardeners’ Chronicle be so kind as to take the trouble to inform me how Dun or Mouse-coloured Ponys (sic) with a dark stripe down their backs are bred? The breed is common in Norway on the banks of the Indus & in the Malayan archipelago, & is in some respects very interesting in relation to the origin of the domestic Horse. Is this peculiar colour thrown from Ponys of any other colour, or must one or both parents be Dun?
- [To T. C. Eyton] Do you know when owl or Hawk eats a little bird, how soon it throws up pellet? Can it throw up pellet whilst on wing? … Could your gamekeepers find a roosting place, & collect a lot for me?
- [To J. D. Hooker] [D]o you remember, whether the introduced Sonchus in N. Zealand, was less, equally, or more common than the aboriginal stock of same species, where both occurred together[?]
- [To T. H. Huxley] Do you know whether the embryology of a Bat has ever been worked out?
Reading through Darwin’s letters, you can’t help wondering whether, on receiving the latest missive from Down House, some of his regular correspondents occasionally wondered, “Oh good grief! What on earth does he want this time?” But such musings are both unfruitful and uncharitable: the truth of the matter is that Darwin was remarkably successful in enlisting the help of others in his research, and the help that he received was willingly and freely given—a remarkable testament to the spirit of co-operation that existed amongst individuals in pursuit of scientific knowledge during the mid-nineteenth century.
Darwin’s other great external source of information was published documents in the form of books, periodicals, and scientific papers. He was a voracious reader, and regularly scanned scientific publications in search of evidence for or against his theories. He did not own copies of all the books he read, but borrowed many of them by post from the libraries of his friends, gentlemen’s club, and various scientific bodies. [A modern bibliophile would shudder to see how Darwin treated the books in his own library, scribbling notes in the margins, and tearing some of the thicker books in half down the spine to make them easier to handle. But to Darwin, books were first and foremost a source of information: they were to be used, not cosseted.]
But Darwin didn’t get all his information through other people’s work. When it came to conducting his own experiments and making his own observations, he was certainly no slouch. Indeed, he was even prepared to carry out exhaustive experiments to verify (or sometimes refute) facts which everyone else deemed so obvious that checking them was unnecessary.
Nowhere was Darwin’s willingness to put accepted truths to experimental test better illustrated than in his investigations into how various plant seeds could be transported across seas (a subject of great importance to his theory of evolution, one consequence of which was that related species on different islands must have descended from a common ancestor). The perceived wisdom of the day was that most seeds would not germinate after being exposed to salt water. Darwin decided to put the accepted dogma to the test. He filled dozens of small bottles with salt-water and placed different types of seeds in each, letting them soak for varying amounts of time before planting them in dishes in his study. To his delight, nearly all of the seeds grew into healthy plants—even after several days in salt-water. But, being Darwin, he didn’t stop there: he wrote to one of his naturalist contacts and asked them to try leaving seeds in the sea; he got the British consul in Norway to send him exotic seeds that had washed up on the local beaches (J. D. Hooker identified them as Caribbean in origin, planted them, and was amazed to see them germinate); he wrote to his cousin to ask him to try similar experiments on lizards’ eggs; and he carried out calculations to see just how far seeds could have been carried by ocean currents.
But, almost as an afterthought, Darwin then realised that there was an important problem with his hypothesis that seeds could be transported across the seas by ocean currents: most of the seeds in his experiments sank! So he began another series of weird experiments to determine alternative ways in which seeds might be carried over great distances: he floated fruit-covered branches in a tank of salt water (they rotted and sank); he tried feeding oats to fish (the fish spat them out); he inspected the feet of downed grouse and ducks for seed-carrying mud; he floated a dead pigeon whose crop was full of seeds in salt-water for a month, then successfully germinated the seeds; he retrieved more seeds from bird droppings and pellets and germinated those too.
Charles Darwin was truly fortunate to be a man of independent means living in a golden age of science: an age when science had become sufficiently advanced to have separated into distinct disciplines, but when a virtual recluse working away in his home in the countryside could still make a revolutionary contribution to his chosen field.
As we progress through the early years of the twenty-first century, the world of modern science—with its industry-sponsored research grants, genetic patents, intellectual property rights, supercomputers, electron microscopes, satellite tracking systems, and rival genome projects—is very different from the scientific world so beloved of Darwin. Cutting-edge modern science consumes big bucks (and copious quids), and is usually carried out by whole teams of scientists. Sadly, there is no longer a place for dedicated amateurs like Darwin.
But hang on a minute! Why shouldn’t there be a place for amateurs in the modern world of science? Darwin didn’t need supercomputers or electron microscopes to carry out his work; all he needed was an enquiring mind, a few good friends to write to, and some (literally) common or garden species to observe and experiment on. Darwin’s revolutionary theory might have been inspired by his round-the-world trip and the wildlife of the Galapagos, but what did he study for the rest of his life, when amassing the bulk of his data? Seeds, garden plants, barnacles, earthworms, etc. If a few thousand personal computer users can help search for extraterrestrial intelligence with nothing more than an Internet connection and some screensaver software, what couldn’t a few thousand amateur scientists achieve if they put their minds together?
Both Darwin Day and the Friends of Charles Darwin were created in order to celebrate the life and works of the world’s greatest amateur scientist. What better way to do this than by following in his footsteps? Not by dreaming up revolutionary new theories, but by observing and experimenting on whatever species are to hand.
For example, every summer my garden is inundated with slugs—thousands and thousands of slugs. What do I do when I see them? I spend many a satisfyingly mindless hour picking them up in a pooper-scooper and slinging them into the adjacent field. I know absolutely nothing about slugs (not even a half-way effective way of ridding my garden of them), but my slug-slinging activities have allowed me, quite unintentionally, to make a number of observations about slugs which might be worthy of further investigation. Here are a few examples:
- the slugs in my garden come in various sizes and colours, but exactly how many species am I dealing with? Are the brown slugs and black slugs different species (as I suspect), or different varieties of the same species. Do the small, white slugs grow into large browns or large blacks or both (or do they stay forever small whites)?
- am I just imagining it, or do some of the slugs actually feed on other slugs?
- for all the thousands of slugs I have found, I have never come across a single snail in my garden. Why is that? Is it too cold (I live in the Pennines)? Do the slugs eat them (see previous point), or out-compete them? Am I just not looking hard enough? Or is there simply not enough calcium in the area to allow snails to make shells (possibly because the soil is too acidic)?
- do the slugs in my garden differ from those in my parents’ garden (separated, as they are, by 60 miles in distance and 220 metres in altitude)?
- like many other gardeners, I half-suspect that the slugs I sling over the wall have a homing instinct. Do they really?
- the slugs seem to have favourite areas in the garden. Why do they favour these areas? Do they have favourite plants to eat or to shelter in, or are the clumpings imaginary?
- is there any pattern in the meandering trails the slugs leave all over my patio?
- are my slug-slinging activities exerting selective pressures on the slugs to grow wings?
I’m sure none of these questions is particularly new or insightful (apart, maybe, from the last one), and finding answers to them is hardly going to cause major rumblings in the professional scientific community, but maybe, just maybe, something useful might come out of my idle musings—such as a new strategy to stop the blighters from eating my potato plants, perhaps.
So why not give it a go? Build yourself a slug-arium; count the spots on ladybirds; look for peppered moths on tree trunks; try to create a blue sweet pea; breed pigeons; find out whether male crustaceans ever fight for the females; look for seeds in bird pellets; try floating seeds in salt-water; keep a notebook; involve your friends; email people; read books; search the web; if you have a website, publish your findings (even if they’re inconclusive).
Above all, exercise great industry in the observation and collection of facts.
Be a scientist.