Another salvo in the evo-wars

kw: book reviews, nonfiction, biology, evolutionary debate, polemics

Jerry A. Coyne isn't going to convince Duane Gish or Pat Robertson, but there's a chance that a good many people will at least find reason not to spend time and effort in fruitless combat. Dr. Coyne has written Why Evolution is True as a direct assault on creationism and "intelligent design", primarily among Americans. As he points, out, the primary resistance to education that includes evolution is found in the United States and in Turkey, the two nations that include large contingents of more fundamentalist believers, though the former is a "Christian nation" and the latter is Islamic.

In his introduction, he allows that religion by itself is not necessarily contra-evolution: "You can find religions without creationism, but you never find creationism without religion." I cannot speak for any Muslims, of course, but among Christians, I do know that the great majority are not zealous creationists, meaning that while they believe in God as the creator, they are not bothered by evolution as a biological explanation for the vagaries of life on Earth.

Isaiah wrote (45:15) to God, "Truly you are a God who hides himself…" I take this to mean that rationalistic inquiry is not useful for finding God. Job admonished his friends, "But it is the spirit in a man, the breath of the Almighty, that gives him understanding." To those who count that the Bible is true, there is a spiritual organ within us that is the right means of learning of God. This spirit is not our mind. Based on this crucial notion, we understand that scientific search and understanding are about the material world only, and cannot research spiritual things.

Then, to take up the author's key arguments, let us use the briefest definition of natural selection, the one favored by Darwin: Natural selection is descent with modification. Every living things shows, whether in its embryonic development or in this or that bodily feature, signs of being modified from earlier beings. Thus, for example, a large class of fishes has four main fins; in a few groups these fins are on lobes that can function as primitive legs. Amphibian legs are clearly seen to be modified from these "lobe-fin" appendages. Reptile legs are a further, more robust development, and mammals and birds have legs that are further refined. Evolution has not changed the number of legs, but has developed the same four legs in various ways. Dr. Coyne writes:

"There is no reason why a celestial designer, fashioning organisms from scratch…, should make new species by remodeling the features of existing ones. Each species could be constructed from the ground up. But natural selection can act only by changing what already exists."

To that last statement, let me add the proviso, that the original features, such as the fishes' fins, were based on simpler structures, but eventually you get an ancestor that didn't have any limbs at all, and somehow they were developed. Producing the first fins apparently took hundreds of millions of years, once the first vertebrates came to be in the first place. Thereafter, amphibians developed from lobe-finned fishes in a much shorter time.

Cartoons like this pretty much sum up many folk's understanding of evolution (Cartoon © Baloo [Rex May]). Somehow, fish "wanted" to go onto land, and amphibians resulted. But, observing fish that can "walk" on their lobe fins, we find that they don't "want" to walk, they have to walk when food runs out or water dries up. Necessity was the mother of this invention also. By the way, lobe-fin fish have really good moisturizers in their skin; the cosmetics industry might wish to take note.

To me, living in a body composed of a large number of features, all modified from earlier beings, can he a bit of a drag. Back troubles that plague more than half of us could have been forestalled were our backbone Designed with verticality in mind! Human bodies are filled with makeshifts like this, that work well enough for thirty or forty years, enough for us to raise children and maybe give a bit of help to the parents of our grandchildren, before we begin to decrepitate and decline. A well-designed human body would function well for a designated span, pre-chosen by its Creator, then a valve would pop off somewhere and "Pow!" we'd be done for. Maybe we'd have a day's notice so we could notify our own next of kin, with a clear schedule. To put it rudely, if my body was designed by God, I have a bone or two to pick with Him!

The author marshals his evidence, like wave after wave of an infantry: embryo development (we start out looking like little fish), geographic patterns of species ranges, sexual selection (the peacock's tail for example), and the mechanisms of speciation, how one species becomes two and so forth. I find the timing of speciation most fascinating. Some creatures, such as the Coelacanth fish and the Ginkgo tree, many sharks and cockroaches, have remained unchanged for tens of millions of years. Other species, particularly among land vertebrates, split and split again every million years or less.

I once read that most mammal species have a natural span of about four million years, but that primates tend to last only a tenth that long. In other words, a population of lemurs, for example, may spread out in the landscape and, because of some barrier between one group and another, evolve into two new species, both of which differ from the "parent" species, in a few hundred thousand years (perhaps fifty thousand generations). Among a different sort of creature, the genetic changes might take ten or a hundred times as long to occur, though a change in environment will hurry things up considerably. However, how long should it take, to produce the great diversity of visible-sized living things?

There are at least ten million species on Earth today, and some claim there could be 100 million or even a billion living species. This is not counting bacteria, which are quite a bit harder to count! How long must the average doubling time be? Let us take our zero point as the end of the Permian, when 99% of living species were wiped out, and assume that ten million species of beetle have arisen from just one beetle species that "made it through" the great Permian extinction.

It takes just 24 doublings to produce more than sixteen million items, from one. The Permian extinction was 251 million years ago, and 251/24 = 10.46. Thus, if each beetle species splits into two new beetle species at least each 10.5 million years, at least 16 million species of beetle might be found today. Actually, beetles speciate faster than that, and many species go extinct without producing any new species.

The author scarcely addresses "young Earth" believers, who don't agree with all this talk of millions of years. They can barely handle the thought of ten thousand years, at the outside. I know some that accept a great age for the Universe, but not for the Earth.

But I also know of a hillside in Wyoming, part of the Yellowstone Petrified Forest, that is actually twenty petrified forests, one atop the next. Each forest contains trees with several hundred growth rings, and fallen logs even larger, so that each required more than a thousand years to develop. Each forest was killed by ashfall from volcanic activity at Yellowstone some time in the past. An unknown interval of time passed after the killing of one forest and the growth of the large trees in the next began. But it is certain that this one hillside contains at least 20,000 years of history, and probably much more.

I know of "varved lakebeds" in Scandinavia, in which a very thin layer of sediment (a varve, usually less than a millimeter thick) is laid down each year; some of these lake bottoms contain more than 100,000 varves. I know of the ice cores drilled in Greenland that contain a continuous record of 400,000 years of snowfall (and dustfall). These are all things that don't depend on radioactive decay measurements.

So, let me say a word to my Christian brethren (sisters included), who are wondering about evolution: it is not anti-God. Believing in Creation does not mean you are a creationist. Creationism is a certain set of beliefs about creation, based on a distorted view of what the Bible is saying. The "Gap" between Genesis 1:1 and Genesis 1:2 is very real, and the language, fairly read, indicates a great upheaval that led to God's Spirit "brooding over the waters." The six-day sequence recorded in Genesis 1 is a restoration from a damaged condition, caused by events mentioned in quite a mysterious way by Isaiah (ch 14), and alluded to by Jesus: "I saw Satan fall like lightning from heaven".

How likely is it that a brief catastrophe, quickly righted by divine intervention, would show up in the sediments? Particularly as it occurred near the end of the last ice age, when the breakup of the ice sheets was causing cataclysms in a number of places, such as the Channeled Scab-lands of Washington and Oregon states.

Jerry Coyne wants to convince those who might be wavering, that evolution actually happened in the way that biologists now think, by natural selection operating over long spans of time. Whether you wish to believe this yourself, I hope that at least you will realize that such a theory does not lead to either better or worse morals, nor is it a threat to the sovereignty and goodness of God. God truly is a God who hides himself, but also One who lets those who seek Him find Him. He isn't afraid of evolution; neither should His people be.