Jeff's Lunchbreak

This entry is part of a series. For a bit of an introduction and an index of all entries in the series, go here.

This installment covers Chapter 8, Hybrids, Haeckel and Confusion and Chapter 9, The Swan Song of Darwinism.

Chapter 8

If only McCann had talked about crocoducks...

Even before Darwinism was abandoned by the modern scientist it was strictly scientific to believe that cats are always cats, whatever the variety, and that though they differ in many and wonderful characteristics within the limit of cat variation, they nevertheless remain in all their variations just what they are-cats. They never mate with dogs, and there are no half-dog half-cat animals even in the dime museums. (McCann 103)

This line of thinking involves two misconceptions tied into one. First, we get the notion of Platonic ideal forms, or Biblical kinds. This, to me, seems like a misfiring of a useful feature of the way our brains work. We categorize things. It's a useful way to make sense of the world, but we have to remember that the categories are in our heads, and there's no reason that the universe needs to oblige us by sticking to those categories. People sometimes extend this concept to say that microevolution is possible (i.e. small changes within a species), but not macroevolution. This seems to be what McCann is saying - that no matter what variation, a cat will always give birth to another cat. But the question is, where's the stop sign in nature that tells organisms to stop changing. Enough small changes added up over generations can result in big differences.

Next, is this weird notion that evolution predicts cats and dogs should be able to mate. This makes no sense whatsoever. Cats and dogs aren't particularly closely related, so there's no reason to suspect that they could interbreed. And evolution certainly doesn't predict that a cat would give birth to a dog, or even a half-dog.

What evolution does predict is that there will be grey areas (in fact, observation of these grey areas was one of the pieces of evidence Darwin used in Origin of Species). If speciation occurs, and evolution is a gradual process, it just follows that speciation won't be instantaneous. Consider a group of animals that gets split into two isolated populations. Just by genetic drift, these two populations will start to acquire different genetic makeups. Now, if you bring the two groups back together after just a few generations, they'll have no problem breeding with each other (like when Europeans and American Indians came in contact). Wait a little while longer to bring the populations back together, and breeding might become more problematic. Maybe some of the offspring will be sterile. Wait even longer, and maybe most of the offspring will be sterile. Wait yet longer, and perhaps even sterile offspring will be rare. Wait long enough, and the populations just won't be able to produce any type of offspring at all.

This is the whole reason why there's a problem in classifying organisms as varieties vs breeds vs species (see lumpers vs. splitters). Just how distantly related do two groups need to be before we call them two species? For example, most people would consider Grizzlies and Polar Bears to be separate species, but they can, in fact, breed and produce fertile offspring.

Another example, which McCann used below, is horses and donkeys. They can mate and produce offspring, but the resulting mules are almost always sterile.

Whatever the variety, dogs always remain dogs, horses always remain horses, jackasses always remain jackasses, and mules, like every other hybrid repugnant to nature, are cut off without offspring. (McCann 103)

Poor mules. Apparently, nature hates them.

Here's another example of McCann not understanding that common descent means humans are related to all organisms, not just that we have a common ancestor with the other great apes.

Darwin, be it remembered, was trying to uphold the theory of natural selection. He had not gone so far as to declare that man's ancestor was one of the great apes. He really did believe that man's descent was from some form of lower ape-like animal, and the student of his "Descent of Man" will recall the illustrations designed to show similarity between the embryo not of man and monkey, but of man and dog! (McCann 109)

Universal common descent really means just what it says.

Of course, McCann brought up the biogenetic law. Creationists still bring up Haeckel, and admittedly, Haeckel was wrong in thinking that "ontogeny recapitulates phylogeny." However, McCann's rationalization for the similarity between embryos is a bit funny. Did he really think this was a good explanation for why all of us humans had tails as embryos?

The apparent repetition of many previous stages of development is accounted for by the fact that it is essential to the very nature of development to advance from what is simple to what is complex. The more highly any animal is organized, the more stages of development must it pass through, before reaching the complex final stage, and it is quite in accordance with nature that the previous transitional stages, being simpler, should resemble the final stages of other animals, which have remained stationary at a lower degree of organization. This constitutes no proof that the human race has passed through all these stages, but it only shows that the evolution of the individual goes on from the first sub-division of the impregnated egg through various stages, until the final form of the perfect organism is reached. (McCann 111)

To quote something that I wrote previously, "evolution is not a transformation of adult animals into adult animals. It is an adjustment of the developmental process - of growing up." That is why early stages of the developmental process look so similar across species.

I know I've already pointed out a couple of quote mines from McCann, but this particular quote mine is one of my pet peeves, after having read On the Origin of Species, and seeing how much space Darwin actually devoted to explaining the evolution of the camera type eye.

However, his comfortable though futile certainty, with regard to the truth of a conviction that has no truth in it, is quite sufficient to him, as an ape-man evolutionist, to offset the deadly complications and massive obstacles involved in the evolutionary riddle: "How did the eye first start?" Darwin himself was baffled by that all but miraculous organ. Referring to Virchow's reverential appreciation of its "beautiful crystalline lens" he says ("The Origin of Species," Appleton, 1920, vol. 1, p. 227) : "To arrive at a just conclusion regarding the formation of the eye, with all its marvelous characters, it is indispensable that the reason should conquer the imagination; but I have felt the difficulty far too keenly to be surprised at others hesitating to extend the principle of natural selection to so startling a length." Let the skeptics pause, for here again Darwin voices belief in God. The succeeding paragraph contains the following: " ... a living optical instrument as superior to one of glass, as the works of the Creator are to those of man."

Of course there can be no explanation of the origin of the eye, about which evolutionists are quite as silent as, in the case of the gills, they are vociferous. (McCann 113-114)

Saying that 'evolutionists' are 'silent' on the evolution of the eye is absurd. It makes one wonder whether McCann had even read On the Origin of Species, as Darwin devoted several pages of the book to discussing eye evolution leading up to that quote that McCann used. If you want to read it for yourself, it's in Chapter 6 of the book.

While Darwin didn't put illustrations in the first book on natural selection, we don't have that shortcoming today. Just take a look at the following illustration showing existing mollusc eyes. Yes, those are existing species, which means that the pinhole eye of Haliotis didn't evolve from the deeply cupped eye of Leurotomaria, which didn't evolve from the cupped eye of Patella. Rather Haliotis and Leurotomaria shared a common ancestor that probably had an eye more like that of Leurotomaria, and in the lineage that led to Haliotis, the eye evolved into the pinhole type, while in the lineage that led to Leurotomaria, the eye didn't change much. What this clearly shows, however, is the usefullness of each stage in the evolution of a complex camera type eye.

If you want to really read up on eye evolution, take a look at this free issue of Evolution: Education and Outreach.

Chapter 9

I almost didn't pick any quotes from this chapter, so I settled on its closing paragraph just to have something.

We have had "early changes of great violence followed by stability;" "slow changes so gentle and infinitesimal in gradations as to require millions of years before they could be observed;" "sudden changes under our very eyes." Alas, what have we not had? And this is what they call evolution! - this ceremonial burial of "Darwinism." (McCann 123)

McCann seems to be bothered by the fact that evolution doesn't always proceed in the same manner. But why should we expect it to? By way of analogy, consider the path rain water takes back to the oceans. Sometimes it's a mighty river like the Amazon. Sometimes there are waterfalls like Niagara. Sometimes it's a meandering river. Sometimes there are rapids. Sometimes it's an inland delta like the Okavango, and the water must evaporate and fall again before going back to the ocean. The point is, even though water flow is controlled by simple laws of physics, the ways in which it flows vary based on local conditions.

Similarly, evolution need not always progress in the same manner. Gradualism is the term for constant, slow change. Punctuated equilibrium is the term that describes periods of stasis, interspersed by short periods of rapid (in a geological sense) change. Both modes of evolution have been observed in the fossil record. It all depends on the conditions.

Proceed to Chapter 10