The Overwhelming Diversity of Life

A post yesterday at Pharyngula has referred to a series of dinosaur parks in the United States that put up an information page on their website revealing a creationist agenda. As I've noted before, I tend not to concern myself with the activities of creationists because I generally find them exceedingly dull (I'm often tempted to repurpose a line spoken by Julian Rhind-Tutt in an episode of Green Wing: "You know what? The rest of us have moved on."). However, my eye was caught by one line that reflects on one of the major misunderstandings involved. In the process of postulating how dinosaurs became extinct subsequent to the Flood:

It is not just dinosaurs that have become extinct. In the last 350 years alone, almost 400 species have disappeared.

For various numbers, the total of '400 species' is probably severely underestimated, but that's not what I want to focus on. Instead, I want to look at the number itself. If there is one thing that most people fail to grasp about biodiversity, it would be that there's just so much of it. It's an understandable failing: I work with biodiversity on a daily basis, and even I find myself constantly startled and awed by this point. So huge are the numbers involved that it's almost counter-productive to simply report them. Humans seem to have a tendency to effectively just lump any number over a hundred or so as simply 'a lot'.

Imagine you were an avid twitcher (one with an enthusiasm for seeing new bird species) who, through a preternatural combination of flawless logistics, limitless funding and exceptional luck, was able to observe one new bird every day. At that rate, how long would it take you see every species of bird in the world? Wikipedia gives a figure of about 10,000 species of bird, which would mean that you would need 27 years, four months and 25 days. If you started at the age of 18, you would not finish until after your 45th birthday. If you moved on to mammals, you would need another fifteen and a half years. Lizards would account for another ten years; snakes another eight. Turtles you would be able to get through in just under a year, but then frogs would require thirteen and a half. Fish, on the other hand, would require the investment of some seventy years. Or, to sum up, observing every known living species of vertebrate at the rate of one a day would require nearly twice as much time as most of us are allotted in a single lifespan.

Outside vertebrates, the numbers just keep adding up. Earthworms may not seem like a hugely diverse group, but would still require an investment of more than sixteen years. You'd need more than 126 years to get through the staphylinid beetles alone. Perhaps plants are more your thing? You'd better have dedication, then: it's going to take you nearly 700 years if you want to see every variety of flower in the world. After that, the mere 33 years required to deal with the ferns will just go by in a flash.

No-one has yet tallied up exactly how many species of organism have been described to date, but using a conservative (very conservative) estimate of 1.5 million, observing every one at the rate of one species a day would take you more than 4100 years. Or 45 somewhat generous life spans (assuming, of course, that you were able to get things started from the day of your birth). Compared to this, 400 species is but a drop.

It was no accident that the concept of evolution achieved its majority in the nineteenth century. Naturalists at that time were required more and more to come to terms with just how diverse the world's organisms were, and how inadequate the popular explanations were in accounting for such diversity. What is one supposed to make of a god who would apparently bless to the world with over a thousand species of tapeworm? Or over 100 species of scabies mite? Unless, of course, we should simply take it as evidence that God has an inordinate fondness for scabies.