Here we have, from San Diego (of course), an email from a man who is an ardent exponent of the Argument for God from Incredulity. I’ve omitted his name so as not to embarrass him. I appear to have been the sole recipient of the email, but given its salutation, it was probably sent to other scientists considered as deluded as I. The theme of this screed is the claim that some animal behaviors are so complex that they could not have evolved by a Darwinian step-by-step process. Ergo, God did it. (You will recognize this argument as the basis for Intelligent Design.) On top of this is laid the idea that an animal, when performing an adaptive act, has to “know” what it’s doing, and animals just don’t have brains like that.
This is a longish email so I’ll briefly discuss only two examples, parasitic larvae keeping their hosts alive by eating only non-essential organs, and the archerfish, which spits water at prey above the water (mostly insects) and is amazingly accurate. In both cases I’ll propose an adaptive pathway that eliminates the necessity for invoking divine intervention.
The email (the bold bits are mine):
To Those of Evolutionary Bent:
This is the story of a wasp (Pompilidae) and a spider (Ctenizidae), or the trap-door spider. The two have a peculiar relationship: the wasp uses the spider as a larder for its young, laying its eggs (or one egg) on or inside the living spider, placing the paralyzed creature back inside its burrow until the wasp larva can hatch out and consume its still-living host.
But this is no easy task. First, the wasp must find the well-camouflaged spider residence. A very good sense of smell, and observation of possible spider burrows from the air or on the ground, depending on the habits of the particular wasp specie, are certainly necessary to the work. Still, considering the area that must be reconnoitered by the wasp to find a spider ensconced in a camouflaged hole in the ground, it is a task that would put many military intelligence workers to shame.
Then the wasp attacks: sometimes is merely pulls on alarm-webbing that surrounds the burrow. This will bring the spider out into the open, expecting a ready-made meal. If the wasp is quick enough, it can sting the spider, perhaps in the midsection, before the creature can react. The spiders, for their part, boast long, deadly (to insects) fangs, dripping with paralyzing poison. The spider may recognize the danger and duck back into its fortress. If it successfully closes the trapdoor, the wasp will be shut out; the spider can hold the door shut with two or four legs, and hold on to its home’s wall with the other four. No problem: the wasp merely chews off the door’s hinges, and comes face-to-face with an angry spider! Then, we have a problem: how the wasp will deal with the spider head-on. Some wasps have a talent for hypnosis; they appear to stroke the spider with their antennae, putting it into a restive state. In other cases, the wasp merely turns her back on the monster Arachnid, and stabs it in the head with her formidable stinger: end of combat. But the beginning of a paralyzed end for the spider.
Then, the wasp can lay its egg; sometimes on and, for other species, inside the spider. Then we have another question: how does the larval wasp, when hatched, know to eat only non-essential parts of the paralyzed spider, in order to keep it alive until it can pupate and become a living, flying wasp? For it certainly eats everything except the vital organs, leaving the best ’til last, when it can gnaw its way to freedom and spread its wings to find a mate and then go spider-hunting.
So all this, the wasp, the unfortunate spider, and their dueling interactions, were brought about by Biological Evolution, a la Charles Darwin or some other foolish inquisitor. Really? You’ll excuse me in my dubiousness. We must add this paradigm to many others: the construction of the mammalian eye and function of the rods and cones; the need for the brain to turn the upside-down image transmitted to it, right-side up. Then there’s the Archerfish (Toxotes), which can “shoot”, via spitting jets of water at its insect prey from an underwater perch, compensating easily for the water’s refraction, even at odd angles. And the Cleaner Wrasse fish (Lambroides dimidiatus) that pops into the mouths of large and dangerous predator-fish to clean them of parasites and dead tissue, even excess mucus; and can “service” up to 2000 “customers” in a four-hour feeding period. Yet, they remain uneaten by sometimes hungry patrons visiting the “cleaning station ” on the reef.
Indeed, there are hundreds, if not thousands of such stories, each more mysterious than the last: all pointing to a Creator, certainly not One Who would use a “dog-eat-dog” process like evolution. But certainly One Who left His fingerprints on all of His work in the creation as we have come to know it.
And what of the variations that occur in the known species, as Darwin himself pointed out in the birds of the Galapagos Islands? Is this, too, “evolution”? Different colors, different beaks, different diets, different sizes and breeding habits– these are all adaptations afforded them for their continued survival in a world where “climate change,” earthquakes, volcanoes, and man’s activities can cause conditions to change. No one so far has noted Darwin’s birds changing into other species or non-avian creatures. Not very likely, I think.
The fact is, that Biological Evolution, of whatever description or fancy, is a Scientific dodge to avoid calling for the creation– and the Creator– in their theories and hypotheses. It is a gigantic academic hoax, that in fact has played a major role in political axioms like Nazism, Communism, and Fascism which have resulted in the deaths of hundreds of millions human beings. And I challenge these scientists who insist that it “must be true” to answer the facts presented here or by numerous other critics to give evidence in support of their positions. We seek the truth of the matter, not mere theories, hypotheses, or suppositions. So far the Scientific World has been unable or unwilling to come up with it.’
Let’s take the larval wasp first. The way to address the incredulity argument is to postulate a plausible step-by-step process in which each step is adaptive. And then couple that with variation in the trait under consideration—variation due to mutation. If the nonadaptive variants leave no offspring, but the adaptive variants do, then you get evolution by natural selection. There’s not necessarily any “knowing” here on the part of the animal, at least in the cognitive sense—just different behaviors that can be performed automatically. A microbe doesn’t “know” to move towards a food source: to paraphrase Jessica Rabbit, it’s just evolved that way.
In the case of the wasp, all that is required is that different larvae have different propensities to eat the organs of the spider. How could this happen? Well, presumably the different organs of a spider can be perceived differently by the larval wasp, either by their location or, more plausibly, by the fact that they “taste” different. If different wasps prefer different “tastes” (or internal locations), and some of that variation is based on variation in genes, then the problem is solved. That’s because those wasps with a taste for the vital organs, or for indiscriminate eating, will kill their hosts early and stand less of a chance of surviving (if you kill your spider host too early, it decays and will not constitute good, fresh food, so that you may die or be malnourished). On the other hand, those larvae having less of a taste for the vital bits of the spider host, and thus which eat those bits last, will be the ones most likely to survive and leave offspring. Over time, this results in the evolution of a behavior in which all wasps eat the nonessential organs first, only finishing up with the vital ones when they’re about to pupate. Note that there is no conscious “knowing” here: all that’s required is variation in how you eat your host, and you need no cognition for that—only an attraction to eating some organs more than others. And this is not implausible.
That takes care of the wasp. How about the archerfish? Well, all you need is a starting behavior that can be improved and refined so that fish can not only spit water at prey above the water, but do it accurately. Of course that seems implausible because it requires that one envision fish that have some tendency to spit water in the first place, and of what use is that?
First, let’s look at how these amazing animals operate:
How could that evolve? While it’s not difficult to see that once you can acquire food by squirting insects and knocking them into the water, natural selection will then improve your aim, enabling you to judge distance, compensate for refraction, and so on. In fact, not just evolution (which involves no “knowing”), but there is also real learning here, as, if you do a bit of Googling, you find that young archerfish are pretty lousy at knocking down their prey, and have to improve their skills with practice. That may be real knowing.
But how did the whole scenario get started? A little more Googling shows that at least some archerfish use a similar technique to displace silt beneath the water, uncovering hidden prey. That’s pretty easy to explain, as you’re not really aiming but foraging, and you already have the equipment to do that: producing jets of water outside of your mouth, which is apparently common in fish. The New Scientist article that I found in about a minute of Googline says this (I’ve put a possible “solution” in bold):
To their surprise, the researchers found that the archerfish were able to alter the length and type of water blast to suit the type of sediment. Their shots were shortest if the sediment was coarse-grained and increased in length as the sand became finer.
“The big question is: how did they know beforehand which type of silt was which, and so how long they should blast it for?” asks [Stefan] Schuster. The answer might be that they are adept underwater shooters in the wild, too.
Which came first – aerial or underwater shooting – also remains to be established.
“Perhaps some tendency to produce underwater jets might have been there first, because this is widespread among fish,” says Schuster. Triggerfish use jets to turn round sea urchins to get access to their soft parts, for example, and lionfish use jets to orient small prey fish for easier swallowing.
“Many other fish and invertebrates forage by disturbing the ground, and this is probably the ancestral condition,” says Alex Kacelnik of the University of Oxford. “Archerfish probably thus started with this ordinary skill then transitioned to targets probably at, or narrowly above, the surface and this created new selective pressures to focus and aim water jets at ever higher targets.”
“It’s a lovely example of the incremental and interactive process of evolution of complex traits through natural selection,” he says.
Schuster says the two techniques might have evolved in parallel, with the fish building on and adapting their skills according to their habitat.
So here we have an initial condition whose evolution isn’t hard to understand. Once you squirt at the silt below you to uncover prey, selection would improve that ability, as would learning, and maybe you’d start homing in on things that you see in the sediment. You then have the ability to be a living squirt gun. If a mutant fish then simply squirted at an object it could see, but one at the surface or above the water, a successful squirt would bring you food, and, importantly, reproduction. You might in fact get more food than other individuals in the population who aren’t aiming at insects directly but just foraging willy-nilly, with most of their squirts being fruitless. And if that were the case, both selection and learning (apparently fish can learn!) would work together to improve the ability of archerfish to squirt at prey above the water. The compensation for refraction, intensity of squirt, and so on, would then be honed by both selection and learning.
Now I don’t know if this scenario really happened, or if both types of squirting evolved together (which is also plausible given that there’s a general advantage to squirting), but we can envision the first steps in the evolution of archerfish behavior—adaptive steps. And the rest, as they say, is commentary (i.e., improvement by selection). No need to default to God.
The rest of the email, including the claims that we see microevolution but not macroevolution, and that Darwinism begat Nazism, Communism, and so on, doesn’t deserve rebuttal here; I’ve done that many times before. And I’m not going to write a personal answer to this fellow (yes, he’s male), as that would mire me in a back-and-forth exchange that would be totally unproductive. I just wanted to give some examples of how the Argument from Incredulity, which of course is the basis for Intelligent Design Creationism, can be addressed by thinking of plausible and adaptive intermediate steps in the evolution of a trait. If you can do that, then there’s no need to posit a God, since ID and the kind of creationism espoused above require that one cannot conceive of an adaptive pathway for the evolution of a trait. If you can, then the whole ID/creationist enterprise, which of course requires the additional postulate of a complex Designer for which there’s no evidence, becomes unparsimonious and superfluous.