Monday, August 28, 2006

More on Evolution

A reader sent me a column by Washington Times columnist Fred Reed as it appears on the website of Rabbi Dovid Gottlieb of Ohr Samayach: .

The column is typical of its genre – half-baked fulminations by people with access to the media but little knowledge of the subject. Not surprisingly, writings in this genre are never submitted to peer-reviewed journals, where they would have to pass the scrutiny of trained scientists who are on the cutting edge of research in the field. When reacting to work like this, one does not know where to begin because the thinking is so garbled. So I'll begin where Reed does, with the chemical origin of life. He is correct in that we do not know with certainty how life arose, and perhaps we never will know. We have some working hypotheses, and there is every reason to suppose that life arose by natural processes. But that question is separate from evolution. We know that the first organisms on earth were simple single-celled creatures, because they are the first to appear in the fossil record. You do not find human skeletons in Precambrian rocks. Even if, as proposed by Sir Francis Crick, those first cells arrived here from outer space, the evolutionary process on earth would begin from there.
Reed states that science is supposed to give clear answers, while evolution offers only "intense faith in fuzzy principles." Science is a rigorous method for answering questions about the natural world, and each answer raises a host of new questions – else scientists would by now have learned all there is to know and gone out of business. Scientific theories generate testable predictions. For instance, evolution predicts that human DNA will be more similar to chimpanzee DNA than to fish DNA. When scientists learned how to sequence DNA that turned out to be the case; evolutionary relationships inferred from comparative anatomy and protein analysis mapped onto DNA. That is as clear an answer as any that will be found in the physical sciences.
Like all work in this genre, Reed's column makes much of gaps in our knowledge of evolutionary biology. For instance, we do not know the exact sequence of genetic mutations that resulted in the human eye or insect metamorphosis, therefore mutation and natural selection can not account for it. True, we cannot yet reconstruct the genetic events in the evolution of any organ, but it is common knowledge that members of a population differ in heritable traits; like begets like. Ever since the invention of agriculture, farmers have been breeding their "best" livestock and crop plants, i.e. those individuals possessing traits advantageous for the farmer. The result is countless varieties of plants and animals tailored to different environmental conditions, market preferences and the like. Evolution works the same way, except that nature does the selecting. There are unanswered questions in our knowledge of evolution, as there are in any area of science, but evolution remains the best fit to observable reality. Indeed, it is the only fit that comes under the heading of science.
Like most authors in this genre, Reed misunderstands the concept of "chance" or "randomness." Mutations are random only with respect to the needs of the organism. They are constrained by neighboring bases in a codon and neighboring amino acids in a protein, among other factors. That explains much of the "unintelligent design" seen in nature. Since Reed and his ilk like to cite the human eye as a "perfect organ" that nature could not have designed, I will point out that the human eye is not perfect at all. The lens stiffens with age, so that by the time we are 40 (i.e. with roughly half our lives ahead of us) it can no longer accommodate to close-up objects and we become dependent on reading glasses. Worse, the retina is inside out, with the rods and cones behind where the optic nerve leaves, resulting in a blind spot. Any intelligent engineer would have put the opening for the optic nerve behind the rods and cones, but nature must work with pre-existing material; it does not have the luxury of starting from scratch. Also, point mutations are not the only source of genetic variation. We have learned in the last generation that the genome in eukaryotes (organisms higher than bacteria) is much more complex than we had thought, with genes and pieces of genes moving from place to place on a chromosome and even jumping from one chromosome to another, in the process switching some genes on and others off. There is every reason to believe that the eukaryotic genome has more surprises waiting to be discovered and to shed more light onto evolutionary mechanisms.

Now, to address some specific errors in Reed's work:
1. Human intelligence appeared too rapidly. We have a fairly complete fossil sequence of proto-humans, and it shows the brain becoming progressively larger over time. We know that, when our ancestors descended from the trees onto open savanna, they became targets for large predators. They (and we) were not large, strong or fast. But with upright posture our forelimbs were free to wield tools and weapons; we could catch our dinner and avoid being dinner with our wits. Larger brains allowed their possessors to evade predators and to catch more prey; more protein in the diet allowed us to build still bigger brains that made us still better hunters, and so forth. The human brain grew rapidly until it literally bumped into an obstacle – the mother's pelvis was only so big. The Bible is not wide of the mark there; difficulty giving birth is the price we pay for being intelligent animals. And until modern obstetrics it was a high price indeed, with death of mother and baby in childbirth being commonplace.
2. Those who deal in human evolution hold The Bell Curve in high regard. They don't. That book was uniformly panned by just about everyone who studies human evolution.
3. Men prefer cute, sexy women; large breasts produce more milk, etc. Balderdash. Ideals of female beauty vary across cultures and even between individual males in the same culture. Most pre-modern cultures idealized women who were "pleasingly plump;" some extra subcutaneous fat was insurance for pregnant women and their unborn children against the periodic famines that characterized pre-modern societies. It is only in recent times that men in advanced societies came to idealize (and idolize) a body type so unrealistically thin that women literally starve themselves to death trying to attain it. Likewise, there is no correlation between breast size and milk yield. Human females probably evolved permanent breasts, and became sexually receptive year-round, to keep the male interested. It was (and is) advantageous for human children to have two parents around – a mother to care for them and a father to bring home the bacon.
4. Why don't Ted Williams' eyes (actually, hand-eye coordination), Muhammad Ali's physique, etc. spread throughout the population? They simply do not confer any survival advantage in modern society unless you are a professional athlete. How many of us work at jobs that require extraordinary (or even ordinary) physical strength, and would starve if we did not possess it? Likewise, modern medicine obviates the need for genes that confer resistance to asthma and a host of other conditions that are now treatable. Rh-negative mothers who give birth to positive babies are now treated with Rh immune globulin to protect subsequent positive babies. We are indeed waiting for natural selection to equip human beings to sit at desks for most of the waking day and eat junk food without contracting heart disease, diabetes and certain cancers, but in the meantime there will be plenty of premature death.
5. Consciousness has physical existence, mapping onto specific areas of the brain. As a function of the nervous system, it is electromagnetic. One must take it into account in describing physical systems with which it interacts.
6. A population must play the genetic hand it is dealt, therefore different populations might solve the same problem in different ways. Primates evolved a highly developed visual system and do well with it. Primitive man in particular was well served by keen vision warning him of approaching prey and predators at considerable distance. Other taxa are served equally well by hearing and/or smell.
7. Kidneys need well developed nerves to maintain chemical homeostasis of blood. Eat a salty meal and you excrete more salt into the urine. Run a marathon in warm weather and you excrete less salt (and less water). Patients on dialysis because their kidneys failed do not have this fine tuning and must eat a very restrictive diet that causes many to become suicidally depressed.

Fred Reed is right that astronomy and geology do not engender as much controversy as evolution, even though they too require an earth that is several billion rather than several thousand years old. That is probably because the average Joe does not really care how old the earth is, but the notion that he is descended from a nonhuman animal gets his dander up. Therefore, anti-evolutionism is usually (not always) found among Christian and Jewish fundamentalists. It should be noted, however, that the controversy is present only among laymen unfamiliar with the theory and the supporting evidence. In the scientific community evolution, owing to its internal consistency and explanatory power, is as robust and well established as any theory in science. The best advice I can give authors such as Fred Reed, and presumably Rabbi Gottlieb, is found in Mishlei 4:7: ראשית חכמה קנה חכמה.


Anonymous cipher said...

Dr. Stern,

I just discovered your blog several weeks ago. After spending much of the past year wading through a fair number of the Jewish blogs and encountering the condescending tone and bias against modernity exhibited by many of the posters and commenters, I find it very encouraging that an observant person is educated in science, and unapologetic for it.

I have two questions regarding this post:

1. When you say that consciousness is a function of the nervous system, are you saying that you believe that’s all that it is? If so, how does this inform your religious beliefs? Do you believe in the continuity of consciousness after death?

2. If you are an evolutionist in the historical (i.e., non-ID) mode, how do you reconcile this with your Orthodox beliefs? I don’t really know what to do with the position that God initiated the natural order, waited billions of years for humans to evolve then began to interact with them. I’m familiar, I think, with most of the various arguments, but either they seem to be variations on the “We can’t know the mind of God” theme, which I find unconvincing, or they rely upon kabbalistic interpretations, which strike me as being highly contrived. In short, it seems superfluous, as though we are holding onto a belief in God for sentimental reasons alone. If it isn’t too personal, I’d be interested in hearing your opinion.

Thank you.

Wed Aug 30, 07:42:00 AM EDT  
Anonymous Anonymous said...

I think you'd be delighted by the book Icons of Evolution by Jonathan Wells .

Thu Aug 31, 12:10:00 AM EDT  
Blogger Neandershort said...

1. Science can deal only in physical, observable reality. As a religious person I do not believe that that is the only reality. Many, perhaps most, of my scientific colleagues will disagree with me there, but that's okay. The "spiritual consciousness" that continues after death is not a brain phenomenon, since the brain decomposes along with everything else, and so science can not deal with it. But as Jews we are not obsessed with the kind of other-worldliness that characterizes other religions. We operate in the physical world. If we accomplish our mission here then the hereafter will take care of itself.

2. From a scientific point of view, belief in God is indeed superfluous, since we can deal only with the natural universe. As a Jew I believe, but cannot prove, that God exists and is behind everything we see in the observable universe. While God can do anything, he chose to create natural law and operate within it, much like the situation in most contemporary monarchies where the king or queen operates within the law (Saudi Arabia being an exception), c.f. the Hasidic concept of tzimtzum. Creating a system that more or less runs itself, even at the cost of some "unintelligent design," is more worthy of the Divine wisdom than God as super magician in the sky, a point made by Rabbi Slifkin in his latest book Challenge of Creation.

Thu Aug 31, 12:18:00 AM EDT  
Blogger Neandershort said...

Jonathan Wells does a good job of pointing up some imperfections in biology textbooks, as if anybody thought that any textbook is perfect. But to conclude that evolution is not robust and supported by the evidence is a tremendous leap of faith. See .

Thu Aug 31, 12:25:00 AM EDT  

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