This article originally appeared in The Skeptic, Volume 5, Issue 5, from 1991.
Arguments advanced against Darwin’s theory often take the general form, ‘Such-and such a biological phenomenon could not possibly have developed by natural selection’. For instance, Bishop Hugh Montefiore, in The Probability of God, argues that since polar bears are not preyed upon by anything, there would seem to be no selective advantage in the white colouration which camouflages them in snow. For another instance, the Open University course, Science and Belief: Copernicus to Darwin, argues that since small projections on an exoskeleton would be useless for flying, insect wings could not have developed by small increments over many generations.
We might expect both these sources to be well informed, but their supposed counter-examples to Darwin’s theory present no difficulty. A polar bear needs to be inconspicuous, not because it is preyed upon, but because it would starve if its intended prey saw it coming and cleared off. David Attenborough’s Life on Earth (published a little before the OU course), conjectures that the proto-wings of proto-insects may have functioned in temperature regulation.
‘Creation science’ tracts are full of further examples, all of which can be answered with a little common sense or a plausible conjecture (and since the question is one of possibility rather than fact, a plausible conjecture is a complete answer). Curiously, however, the opponents of Darwin, ignore a well known biological phenomenon for which there is as yet no explanation consistent with Darwin’s theory: sex.
Organisms which are male and female, or hermaphrodite, use up a lot of energy on the uncertain business of getting the sperm or pollen to the eggs. Parthogenic organisms like dandelions and stick insects can breed without the pother and waste of getting fertilised. Sex benefits the population by genetic recombination over many generations. But natural selection operates on individuals, not populations, and parthogenic individuals clearly stand a better chance of passing on their genes. The Darwinian presumption is that some ancestor gained some individual advantage from sex, but nobody can think what the advantage might have been.
Single-celled eukaryotes reproduce by simply dividing, but as anyone may learn from a GCSE biology text, they also have sex, uniting in pairs for the sole purpose of rearranging their genetic material. In the animal Paramecium, two individuals occasionally stick together while their nuclei divide, and each transfers half of its genetic material to the other. In the plants Spirogyra and Chlamydomonas, two individuals occasionally merge into a single individual with double the number of chromosomes, which divides again with the genetic contents recombined. Again, the genetic combination is of long-term advantage to the population, but it would be easier and safer for the individuals if they stuck to reproduction by dividing. Genetic recombination certainly occurs among bacteria, but the mechanics of transfer are still in doubt because it is difficult to catch them at it. When sex among simple organisms is better understood, we may be able to say what started it. For the time being, however, imaginations are flummoxed.
One might expect opponents of Darwin’s theory to attack this point of weakness with enthusiasm, banging on about sex at every opportunity. But in fact they hardly ever mention the subject. Why not? I do not know, but I offer a plausible conjecture.
Argument from design.
There is a classic argument for the existence of God called the Argument from Design. In the lucid language of William Paley (Natural Theology, 1815), ‘Suppose I had found a watch upon the ground, and it should be inquired how the watch happened to be in that place, I should hardly answer that for anything I knew, the watch might always have been there. The watch must have had a maker, who comprehended its construction and designed its use. Every indication of contrivance, every manifestation of design which existed in the watch, exists in nature, with the difference on the side of nature of being greater or more, and that in a degree which exceeds all computation’ .
This is an elegant argument, of which creation science writers seem very fond. Their books have chapter headings like ‘The Amazing Design of Living Things’ and ‘The Incredible Cell’. Darwin’s theory does not logically imply the non-existence of a Divine Creator, but it answers the Argument from Design. Perhaps the main intention of creation science is to rescue the Argument from Design from being answered.
It is difficult to talk of sex without thinking of our own sexuality. If creation scientists were to mention sex, that would draw attention to human reproductive organs, and to the messy way in which our reproductive organs are conflated with our excretory organs. One can hardly rescue the Argument from Design by mentioning that. What sort of Designer puts the nursery in the sewer?
