Close readers of my entire oeuvre [if, indeed, there is anyone in the world who answers to that description] will know that one of my all-time favorite philosophical passages is the exchange in the Gorgias in which an exasperated Callicles complains, "Socrates, you always keep saying the same thing over and over again !", to which Socrates replies, "Not only that, Callicles, but on the same subjects, too." [490E] We are all aware that bloggers have their hobby horses, and the pressure of writing something every single day makes those emphases ever more evident. Markos Moulitsos at The Daily Kos can be counted on to take note of local elections around the country, no matter how obscure. Andrew Goodman seems to care principally about religion and beards. Now, I do my best to range broadly over the universe of possible topics [leaving to one side, to be sure, Miley Cyrus and the Kardashians], but I have noticed a tendency to come back to certain subjects perhaps more than the interest of my readership warrants [I mean, does anyone except Goodman really care about beards?]
One of my lesser obsessions is the necessity, when speaking about the validity of Neo-Darwinism and related issues, of actually taking more than a cursory look at the actual science being done by real practitioners in the field. This was the thrust of my criticism of Tom Nagel's new book, and just last Saturday, I posted a comment I had sent to my sister on the book I am reading about parasites [The Art of Being a Parasite, by Claude Combes.]
I continue to make my way very slowly through the book, which is, in fact, only 250 pages long, and on virtually every page I encounter astonishing examples of the endless adaptability of living things. Let me give just two examples from the hundreds that Combes details. The subject, remember, is parasites, of which there are innumerable species. Apparently it is quite common for a parasite to go through two or even three hosts during its life cycle, moving from host to host when the second host eats the first host and the third host eats the second. There is a parasite that starts life inside a mollusk, moves on when a fish eats the mollusk, and completes its life journey in a bird that eats the fish. In order to improve its chances of finding that third host [so to speak -- there is no intentionality or even knowledge here, only endless variation and natural selection], the parasite excretes a molecule that alters the expression of certain genes in the fish, with the result that the physical appearance of the fish changes, making it more likely to become the target of a bird looking for a meal.
In another case that Combes details, a parasite makes its way into the blood stream of its first host, and in order to move on to its intermediate host, a mosquito, must be in the peripheral blood vessels near the surface of the skin, so that a bite by the mosquito has a good chance of incorporating the parasite, which will then be passed on to its final host when the mosquito bites it in turn. But the mosquitoes in question only bite at dawn or dusk, so the parasite must migrate from the interior blood vessels to the peripheral ones at the right time of day in order to maximize its chances of making the essential leap to the mosquito.
Think for a moment about the process, carried on through innumerable life cycles of the parasite, in which random variations and mutations get selected by the mechanism Darwin first described, eventually establishing this pattern. And remember that since there is, Nagel to the contrary notwithstanding, no teleology in nature, each intermediate change leading to the final extraordinary adaptation must itself have some differential survival value that can be selected for.
Scientists like Combes are like old vaudeville comedians. "You liked that story? I've got a million of them!" And so he does. To be sure, he arranges them thematically, illustrating them with splendid drawings, but down deep Combes, like many research scientists, is a connoisseur of the minutiae of the endless variety of species adaptations. I think of him as having the same sort of sensibility as the great American historian Leon Litwack, whose brilliant book, Been in the Storm so Long, is an endless feast of individual detailed accounts of the responses of former slaves to the experience of liberation.
By all means argue about the Big Questions -- Is Neo-Darwinism Dead? But before you do, immerse yourself in books like the Combes and really taste, savor, enjoy the diversity of living things. And when you come to make your arguments, pair every theoretical claim with some specific examples and see whether those claims sound as plausible in the presence of Nautilus snails, nematode worms, or parasitic Microphallus trematodes [yes, Microphallus means what you think it means, although inasmuch as we are talking about little buggers a centimeter or two in length, it is a little hard to imagine what a Macrophallus could possibly be.]