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The DNA Disaster

The DNA Disaster


Have you ever imagined yourself as a best selling author? Detective stories sell well. Let’s give it a try. My story is set in an imposing country home in England. The wealthy owner happens to wander into his wife’s dressing room. She is away on an expedition to the beach. The gentleman notices his wife’s diamond necklace carelessly flung onto the table amidst expensive perfume bottles. Horrified, he swoops down upon the jewelry, only to discover that this is a cheap imitation of the real necklace. Promptly he calls the local inspector who sends out four detectives. The detectives snoop around and each presents his theory on the case. Detective Smith declares that the butler stole the necklace and sold it in London. Detective Jones strongly suggests that his evidence implicates the maid. Detective Cooper accuses the daughter’s boyfriend of helping himself to the jewels. Detective Trent indicates that the evidence points to the son of the family who has wasted huge sums of money on fast cars. The gentleman is now thoroughly confused. When his wife returns home, he shares all these distressing details with her. It is then that his wife informs him that actually she lent the real necklace to her sister, Lady Hampton, who is scheduled to attend a royal court event that very evening.

You may imagine that this is a pretty ridiculous story. Why would the home owner not first establish that a crime had indeed been committed? Did the lack of agreement among the detectives tell him something about the dubious nature of their theories? These are all excellent questions! They show that you are thinking critically. The whole thing reminds me of a remark I read in the scientific literature the other day. The author was Dr. Simon Conway Morris from University of Cambridge in England. This palaeontologist is well known for his studies on Burgess Shale fossils. The Burgess Shale, you may remember, is the fossil bed in British Columbia which was made famous by Stephen Jay Gould in his book Wonderful Life.

Recently Dr. Morris wrote a review on the state of our “understanding of evolutionary processes.” He certainly caught my attention with his opening sentence: “When discussing organic evolution the only point of agreement seems to be: ‘It happened.’ Thereafter, there is little consensus, which at first sight must seem rather odd.” (Cell volume 100 pp. 1-11 January 7, 2000). Now of what situation does that remark remind me???? Various explanations which don’t agree…Hmm. The focus of Dr. Morris’ article is that standard evolutionary interpretations (based on fossils and the structure and function of living organisms), do not agree with evolutionary theories which are based on genetic information.

Dr. Morris describes the situation more fully. Studies of DNA sequences (information coded in chemical form) reveal that wildly different organisms nevertheless share some very similar genes. What then explains the great differences between these organisms? What actually do scientists know about the connection between genetic information and the appearance and biology of any given living organism? A further serious problem is the large discrepancies (lack of agreement) between proposed lines of descent which are based on form and function of organisms, and those proposed lines of descent which are based on DNA data. Dr. Morris points our that “Constructing phylogenies [evolutionary trees] is central to the evolutionary enterprise, yet rival schemes are often strongly contradictory. Can we really recover the true history of life?” (p. 1)

Thus analysis of the order of the chemical components of DNA has resulted in two major problems for evolution theory. The most important problem is that similar lifestyles in similar organisms have, all too frequently, been found to be controlled by different genes. The evolutionary expectation is that similar information, but slightly modified, should control the biology of similar organisms. For example, Dr. Morris describes the case of two quite different fish, Eigenmannia, which lives in South America and Gymnarchus, which lives in Africa. These fish share an interesting talent. Each produces an electric signal that confuses predators which want to eat them. These fish use identical techniques to produce these signals. However when these fish are compared, the signals emerge from entirely different parts of the brain. While the end result is the same, quite different genetic information must be involved. The situation might be likened to two very different codes [abcdefg and jkljklm] which apparently communicate the same message and thus produce the same effect. Dr. Morris wonders, and a lot of other people are also wondering, how we can explain this in terms of the process of evolution.

It is tempting to reflect that this might not be a situation where chance was involved. Rather, these organisms may have been designed that way. Dr. Morris actually mentions “teleology” (planning and purpose) on p. 8 of his article. The science textbooks have, for many generations, soundly rejected any teleological explanations. Their dislike of the idea may come from the fact that planning and purpose are usually attributed to God. The other problem that Dr. Morris considers is how the development of vastly different organisms is nevertheless controlled by very similar genes. Why is it that in one case a round worm develops, and in the other a fruit fly appears? This would be like the codes ABCCABCC and ABDDABDD producing round worms, and fruit flies, respectively. Again, it’s hard to explain in terms of evolution theory. Were these codes simply designed to produce different organisms?

Lastly Dr. Morris mentions a problem for evolution theory which he terms “almost intractable” (p. 8) or almost impossible to solve. The problem concerns prokaryotes or microorganisms which lack a nucleus. One of the experts who has recently discussed these relationships, is on the faculty of a university in the Canadian Maritimes. In two recent papers (Science 25 June 1999 pp. 2124-2128 and Scientific American February 2000 pp. 90-95), Dr. W. Ford Doolittle discusses the implications of DNA data obtained from microorganisms. The bad news is that the data do not fit any kind of evolutionary pathway of descent. In fact, no consistent pattern of any sort can be discerned. Dr. Doolittle concludes: “Some biologists may find these notions confusing and discouraging. It is as if we have failed at the task that Darwin set for us: delineating the unique structure of the tree of life. But in fact, our science is working just as it should.” (p. 95)

Dr. Doolittle, and other authors as well, explain this jumble of DNA sequences as having resulted from multiple “lateral transfers” of genetic information between unlike microorganisms. That is, big chunks of DNA are imagined to have been copied and shared with other organisms. This explanation however goes against common sense. As Dr. Doolittle admits “But few researchers suspected that genes essential to the very survival of cells traded hands frequently …. Apparently we were mistaken.” (p. 94) The result of these studies is that scientists now suspect that “the history of life cannot properly be represented as a tree.” (Science 25 June 99 p. 2124). The famous evolutionary or phylogenetic tree now appears not to have a trunk, but rather a net at its base. The illustrations depict a pattern that is wider and wider with more and more separate branches. It appears that scientists are moving closer to the idea of separate creations of the biological kinds. So far, few experts are questioning the basic idea of evolution. However, as Dr. Morris points out, that is their only point of agreement. We can only wonder how long it will be before scientists admit the data simply do not fit evolution theory. That will be a remarkable day!

April 2000

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