Vol 447|28 June 2007 BOOKS & ARTS Falling over the edge Claims that an intelligent designer is needed to explain evolution of complex systems are deeply flawed. The Edge of Evolution: The Search for the Limits of Darwinism by Michael Behe Free Press: 2007. 336 pp. $28 Kenneth R. Miller Michael Behe’s new book, The Edge of Evolu- tion, is an attempt to give the intelligent-design movement a bit of badly needed scientific sup- port. After a spectacular setback in the 2005 Dover, Pennsylvania, intelligent-design trial (Nature 439, 6–7; 2006), and the 2006 elec- toral losses in Ohio and Kansas, the movement could use some help — and Behe is eager to provide it. Knowing how easy it is to demonstrate the workings of evolution in the development of drug resistance in viruses, bacteria and pro- tozoan parasites, Behe concedes the point that evolution works very well at this level. His case study, repeated almost to the point of tedium, is malaria. Resistance to drugs such as chloroquine has indeed arisen within the parasite population, and so has genetic resist- ance to the parasite in humans. But if the inter- Far from finding a clean edge to evolution, Behe’s poorly designed arguments crumble away. species genetic warfare between Homo sapiens and Plasmodium is actually a prime example of badly designed argument collapses under its these two exact mutations occurring simultan- evolution, how can it then be used to make the own weight. eously at precisely the same position in exactly case for ‘design’? Behe cites the malaria literature to note the same gene in a single individual. He then The reason can be found in the book’s title. that two amino-acid changes in the digestive- leads his unsuspecting readers to believe that To Behe, the genetic changes in both parasite vacuole membrane protein PfCRT (at posi- this spurious calculation is a hard and fast sta- and host represent the absolute limit of what tions 76 and 220) of Plasmodium are required tistical barrier to the accumulation of enough darwinian processes can accomplish, and mark to confer chloroquine resistance. From a report variation to drive darwinian evolution. IMAGES L. CIAPPONI/GETTY the “edge of evolution”. He describes these well- that spontaneous resistance to the drug can be It would be difficult to imagine a more understood mutations as a kind of “trench war- found in roughly 1 parasite in 1020, he asserts breathtaking abuse of statistical genetics. fare” in which parasite and host endure a series that these are the odds of both mutations aris- Behe obtains his probabilities by considering of destructive mutations in key elements of cel- ing in a single organism, and uses them to each mutation as an independent event, rul- lular machinery. These changes produce noth- make this sweeping assertion: ing out any role for cumulative selection, and ing genuinely new, serving only to block the requiring evolution to achieve an exact, pre- parasite or render widely used drugs ineffective “On average, for humans to achieve a determined result. Not only are each of these by altering target proteins or clearing damaged mutation like this by chance, we would need conditions unrealistic, but they do not apply cells. The fact that centuries of conflict between to wait a hundred million times ten million even in the case of his chosen example. First, parasite and host have produced nothing in the years. Since that is many times the age of he overlooks the existence of chloroquine- way of new, complex systems in either species the universe, it’s reasonable to conclude the resistant strains of malaria lacking one of the is proof that this is all that evolution can do. following: No mutation that is of the same mutations he claims to be essential (at position They mark the “limits of darwinism”. complexity as chloroquine resistance in 220). This matters, because it shows that there Where does this leave evolutionary expla- malaria arose by Darwinian evolution in are several mutational routes to effective drug nations of more complex systems? Behe tells the line leading to humans in the past ten resistance. Second, and more importantly, Behe us frankly that darwinism cannot account for million years.” waves away evidence suggesting that chloro- even a modest share of the complexity of life, quine resistance may be the result of sequen- and therefore design is absolutely required as Behe, incredibly, thinks he has determined tial, not simultaneous, mutations (Science 298, an explanation. Yet, at the heart of his anti- the odds of a mutation “of the same complexity” 74–75; 2002), boosted by the so-called ARMD darwinian calculus are numbers not merely occurring in the human line. He hasn’t. What (accelerated resistance to multiple drugs) incorrect, but so spectacularly wrong that this he has actually done is to determine the odds of phenotype, which is itself drug induced. 1055 BOOKS & ARTS NATURE|Vol 447|28 June 2007 A mistake of this magnitude anywhere in a book on science is bad enough, but Behe has EXHIBITION built his entire thesis on this error. Telling his readers that the production of so much as a single new protein-to-protein binding site is A Wellcome addition “beyond the edge of evolution”, he proclaims darwinian evolution to be a hopeless failure. The Wellcome Collection and a Hollywood humidor, its handsome Apparently he has not followed recent studies by the Wellcome Trust walnut cases, drawers and hidden cabinets exploring the evolution of hormone-receptor 183 Euston Road, London reveal a telling fraction of the objects Sir Henry complexes by sequential mutations (Science www.wellcomecollection.org amassed. There are amputation saws, birth- 312, 97–101; 2006), the ‘evolvability’ of new ing tools, diagnostic dolls, arresting paintings functions in existing proteins — studies on Sara Abdulla and glassware galore. Medicine Now brings serum paraxonase (PON1) traced the evolu- A unique cultural venue opened in London the story of ‘what it means to be human’ up to tion of several new catalytic functions (Nature this month. The Wellcome Collection is the date, in a bright white and red journey through Genet. 37, 73–76; 2005) — or the modular evo- first permanent home for the massive, mav- malaria, obesity, genomics and more. lution of cellular signalling circuitry (Annu. erick history-of-medicine collection that Throughout the building, subtle curation and Rev. Biochem. 75, 655–680; 2006). Instead, he pharmaceutical entrepreneur Sir Henry Well- sumptuous display invite visitors to reflect on tells his readers that there is just one explana- come (1853–1936) gathered throughout his our knowledge, hopes, fears and beliefs about tion that “encompasses the cellular foundation life. Thirty million pounds (US$60 million) the body. This dialogue will continue in The of life as a whole”. That explanation, of course, and decades in the making, the free venue has Forum, an auditorium for debates, workshops, is intelligent design. three galleries, one of the world’s most impor- lectures and performances. Some of these will The sad mistake at the logical centre of this tant history-of-medicine libraries, an original engage with themes of the temporary exhibi- book is eerily reminiscent of a similar claim in programme of live events, a members’ club, tions. For example on 5 July, the audience can Behe’s 1996 book Darwin’s Black Box. In this a bookshop, a café, a conference centre and watch a live video link to a heart-valve opera- work he claimed that complex biochemical Pablo Picasso’s Bernal mural. tion, ask questions of the surgeon and examine systems have a property he called “irreducible Wellcome’s fortune also created the Wellcome instruments akin to those being used. Other complexity”. Irreducibly complex structures, Trust, Britain’s main bioscience research fund- events, such as the Islam and medicine panel such as the bacterial flagellum, could not ing agency. The trust has now remodelled the on 19 July, will respond to current affairs. have evolved because they lack any selectable compact 1930s building it recently vacated to The second floor brings the trust’s vast function until all of their component parts realize Sir Henry’s vision of a ‘Museum of Man’ library into the twenty-first century. Virtual are in place. As he wrote, “any precursor to and to extend its public engagement activities. browsing stations and WiFi now complement an irreducibly complex system is by defini- The scholarly heat rises with each floor. Street the graceful galleries long beloved by science- tion nonfunctional”, since every part of such a level lures in passers-by from the thundering and-society scholars (and TV crews in search system had to be in place for natural selection road outside with a chic café and striking large- of instant gravitas). The top floors house The to favour it. Therefore, such structures must scale works — including a pendulous Antony Wellcome Trust Centre for the History of have been designed. A nice argument, except Gormley cast. Here temporary exhibitions Medicine at University College London, where for the annoying fact that it is wrong. Subsets will explore the interplay between advances in much of this thoughtful activity starts. of proteins nearly identical to those in the medical science and our view of ourselves. The And what of the members’ club? Will it flagellum do indeed have selectable functions opening show, The Heart, runs until 14 Septem- become biology’s Algonquin Hotel? Quite (Nature Rev. Microbiol. 4, 784–790; 2006), and ber 2007; it features Andy Warhol prints, Leon- possibly: it is inside a thrilling new museum, the argument fails. In the same book, Behe also ardo da Vinci anatomical drawings and a wall of beside a leading medical school, opposite Lon- claimed that every component of the irreduc- fixed animal hearts.