Evolution by Design?

book reviews

Flamsteed was intrigued, and near the end of system by randomly combining numerous The second argument is that of “irre- his life he remarked to Sharp: “You see that individual components. This is a variant of ducible complexity” — that a piece of neither Age nor Infirmitys, nor any discor- Hoyle and Wickramasinghe’s old claim that biological machinery made up of many agements hinder me from seeking after the probability of assembling a functioning integrated components, such as a bacterial knowledg and Truth.” protein out of a random set of amino acids is flagellum, may fail to work if even one of Particularly revealing were the now- similar to that of Concorde being construct- them is removed. This is taken to imply that it forgotten amateur astronomers who wrote ed by a tornado hitting a junkyard. As could not have evolved via a series of func- detailed letters comparing their observa- Darwin made abundantly clear, this is not tional intermediates. Again, this argument tions with a variety of competing astronomi- the way that evolution by natural selection was considered by Darwin in his famous cal tables. Clearly the “great inequality” of is thought to work. Rather, a step-by-step discussion of the eye. Darwin pointed out Jupiter and Saturn was raising its head, not adjustment of individual characters occurs, that, although we have no evidence about the to be solved till the end of the eighteenth each of which is advantageous in terms of actual historical course of events that led to century. In the final paragraph Flamsteed darwinian fitness. the evolution of the vertebrate eye, we do wrote to Sharp, a month before his death, he After a good deal of twisting and turning, have many different types of eyes represen- remarked: “but Saturn and Jupiter will find Dembski concedes that this model of adap- ted among living animals, ranging from worke for those that come after us.” I tive evolution can indeed work, and produce simple light-sensitive cells to the elaborate Owen Gingerich is at the Harvard-Smithsonian the appearance of design. But he then argues camera-like eyes of cephalopods and verte- Center for Astrophysics, Cambridge, that there is still no “free lunch”, since we have brates. A series of gradual steps leading from Massachusetts 02138, USA. to be able to explain the trajectory over time the simplest up to the most elaborate eye can of the relationships between character states be reconstructed, each of which involves a and fitness. According to him, this requires light receptor that is of use to its possessor. the intervention of an intelligent designer, Like other historical sciences, evolution- rather than the interaction of an evolving ary biology attempts to interpret the past in Evolution by population with a changing physical and the light of processes that can be observed to biotic environment. This ignores the large be acting today. The direct record of what design? body of biological evidence on the emergence actually happened, as revealed in the fossil No Free Lunch: Why Specified of evolutionary novelties in response to record, is necessarily incomplete, especially Complexity Cannot Be new environments, seen on a small scale in with respect to very remote events such as the Purchased without Intelligence island radiations such as Darwin’s finches, origin of life itself. Nevertheless, we can ask if by William A. Dembski and on a large scale in such events as the what we see in the living world, both in the Rowman & Littlefield: 2002. 432 pp. $35, £27 evolution of mammalian groups after the past and today, is consistent with what is Brian Charlesworth extinction of the dinosaurs. expected from our models of evolution. The scientific literature on evolution is full of Newton believed that his discoveries examples of people trying to do just that. revealed the Universe to be subject to the For example, if a lack of intermediates is a “counsel and dominion of an intelligent and product of the incompleteness of the fossil powerful Being”. A century later, Laplace record, we would expect to see more and famously remarked that “I had no need more discoveries of intermediate forms as of that hypothesis”, after completing his time goes by. Human evolution provides an revision of celestial mechanics. The whole excellent example of this, with the fossil enterprise of modern science is built on the discoveries of the twentieth century pro- assumption that nature can be understood viding a resounding confirmation of without appealing to the intervention of Darwin’s hypothesis of an African origin of gods or goblins. Most people would agree modern humans. that it has been remarkably successful. In contrast, Dembski prefers to fill up William Dembski and his fellow advo- the gaps in our knowledge by invoking an cates of “Intelligent Design” want to turn the agent whose acts have no observable con- clock back. They claim that darwinian evo- sequences. He smugly refuses to provide lution is inadequate to explain the intri- any details of what the designer has in mind. cate adaptations that can be seen in His theory can explain anything, and there- even the simplest single-celled organ- fore explains nothing. If one tries to imagine ism. Their position differs from that of what the designer is like by looking at the the biblical creationists in that they accept facts of biology, one is likely to come the scientific estimates of the age of the Earth to rather uncomfortable conclusions. and the Universe, and even allow a limited As J. B. S. Haldane wrote in 1932: “Blake role for evolutionary processes such as nat- expressed some doubt as to whether God ural selection. Their arguments are dressed had made the tiger. But the tiger is in up with a good deal of philosophical and many ways an admirable animal. We have mathematical formalism, but conclude with now to ask if God made the tapeworm. an appeal to the continual intervention of And it is questionable whether an affir- an unobservable designing intelligence Rocky blues mative answer fits in either with what we in the course of nature. This smacks of the know about the process of evolution or what Middle Ages. Azurite, found in Chessy, France. Taken from many of us believe about the moral perfec- Dembski uses two arguments, neither of Photographic Guide to Minerals of the World tion of God.” I which is new. The first is based on the prob- by Ole Johnsen (Oxford University Press, Brian Charlesworth is at the Institute for Cell, lem of “specified complexity”: the improba- £17.99, $29.95), originally published in Danish. Animal and Population Biology, University of bility of assembling a functioning complex Edinburgh, Edinburgh EH9 3JT, UK.