Bad AnalogyOne of the powerful arguments for evolution is that the species and the various biological organs and structures fall into the expected common descent pattern. We may not understand how they could have evolved and what transitional forms led to what we observe, but if they were created would they not show discontinuities from species to species? Darwin captures all of these ideas in this famous passage from Origins:
Although in many cases it is most difficult to conjecture by what transitions an organ could have arrived at its present state; yet, considering that the proportion of living and known forms to the extinct and unknown is very small, I have been astonished how rarely an organ can be named, towards which no transitional grade is known to lead. The truth of this remark is indeed shown by that old canon in natural history of "Natura non facit saltum." We meet with this admission in the writings of almost every experienced naturalist; or, as Milne Edwards has well expressed it, nature is prodigal in variety, but niggard in innovation. Why, on the theory of Creation, should this be so? Why should all the parts and organs of many independent beings, each supposed to have been separately created for its proper place in nature, be so invariably linked together by graduated steps? Why should not Nature have taken a leap from structure to structure? On the theory of natural selection, we can clearly understand why she should not; for natural selection can act only by taking advantage of slight successive variations; she can never take a leap, but must advance by the shortest and slowest steps. [Charles Darwin, Origin of Species, 1st ed., 1859, Ch. 6, p. 194]
Here Darwin makes a compelling argument for his theory. Isn’t it a bit suspicious that all those “parts and organs” from so many different species fall into a common descent pattern with small, gradual steps of change between them? Why would they be created that way by an all-powerful designer?
You can imagine how many readers have been swayed by this passage and others like it in Origins. There’s only one problem: This is all wrong.
The species and their “parts and organs” do not fall into such a pattern. Similar species have very different parts, and distant species have very similar parts. These cases are not exceptions but rather are rampant in the biological world and evolutionists maintain their common descent narrative to this day only by careful filtering of the data. Even in Darwin’s day there were hints of this problem and in one of those often overlooked foibles Darwin addressed this just before the passage above:
The electric organs offer another and even more serious difficulty; for they occur in only about a dozen fishes, of which several are widely remote in their affinities. Generally when the same organ appears in several members of the same class, especially if in members having very different habits of life, we may attribute its presence to inheritance from a common ancestor; and its absence in some of the members to its loss through disuse or natural selection. But if the electric organs had been inherited from one ancient progenitor thus provided, we might have expected that all electric fishes would have been specially related to each other. Nor does geology at all lead to the belief that formerly most fishes had electric organs, which most of their modified descendants have lost. The presence of luminous organs in a few insects, belonging to different families and orders, offers a parallel case of difficulty. Other cases could be given; for instance in plants, the very curious contrivance of a mass of pollen-grains, borne on a foot-stalk with a sticky gland at the end, is the same in Orchis and Asclepias,—genera almost as remote as possible amongst flowering plants. In all these cases of two very distinct species furnished with apparently the same anomalous organ, it should be observed that, although the general appearance and function of the organ may be the same, yet some fundamental difference can generally be detected. I am inclined to believe that in nearly the same way as two men have sometimes independently hit on the very same invention, so natural selection, working for the good of each being and taking advantage of analogous variations, has sometimes modified in very nearly the same manner two parts in two organic beings, which owe but little of their structure in common to inheritance from the same ancestor. [Charles Darwin, Origin of Species, 1st ed., 1859, Ch. 6, p. 193]
Here Darwin notes that there are several examples of similar organs in more distant species, indicating that they must have evolved independently. These are the sorts of similarities that would have been ascribed to evolution’s common descent, as in the powerful passage quoted above, if they had appeared in sister species. But these similarities do not appear in sister species—they appear in more distant species. So Darwin produced a new explanation: they evolved independently just as “two men have sometimes independently hit on the very same invention,” such as Leibniz and Newton independently developing calculus. Such personification of evolution and natural selection was common in Origins, and remains common in today’s literature. Aristotelianism never really died, it just changed names.
This has the virtue of not having to explain how low entropy, high Kolmogorov complexity designs which are astronomically unlikely to have spontaneously arisen (yes, that is what evolution says) even once could have evolved, err, multiple times independently.
And so there you have it. Evolution can explain common descent patterns and .NOT. common descent patterns. This is an example of the great flexibility of evolutionary theory. It doesn’t matter what the pattern is, evolution can explain it. And if a theory can explain both X and not X, then the scientist must not claim X (or not X) as evidence for his theory.
But this isn’t about science. Look at the first passage quoted above. Halfway down Darwin makes the argument compelling. Sure there are species that don’t fit the common descent pattern, but the important point is that the species would not have been created this way. X is powerful evidence, not because evolution can explain it but because creation cannot explain it. Evolution must be true—our religion demands it.
Religion drives science, and it matters.