review # 117
Dave@CBS.dtu.dk from Copenhagen, Denmark , March 23, 1999
A biochemist responds to Behe's challenge
As a biochemist interested in DNA structures and the origins of complex systems, I was delighted to hear that someone in my area of research had written a book on this subject. Behe does a good job of trying to convey the problem. If anything, molecular systems are even MORE complex than detailed in his well written and wonder-filled descriptions. However, I was surprised and frustrated to find the use of poor logic and factual errors throughout the book. For example, Behe can't find articles that he LIKES about the molecular evolution of flagella, so he then proceeds to claim that these articles simply don't exist. There are entire textbooks with titles like "Molecular Evolution" (search Amazon.com and see for yourself), and yet Behe insists that nothing has been written on the subject, and concludes that the reason for this is because no one has been able to find any detailed evidence for molecular evolution.
One of the examples cited of "irreducible complexity" is the bacterial flagellum. Behe claims that 40 proteins are necessary for a fully functional flagellum. Whilst this is true for E.coli, flagella in many bacteria are made from fewer proteins - for example, in the bacterium that causes syphilis (Treponema pallidum), there are a total of 38 flagellar proteins; in the bacterium that causes lyme disease (Borrelia burgdorferi), there are only 35 flagellar proteins; finally, in a bacteria associated with ulcers (Helicobacter pylori) there are only 33 proteins necessary to form complete, fully functional flagella. It is likely that as new bacterial genomes continue to be sequenced (at the rate of about one a month!), organisms will be found which require even fewer genes to make a completely functional flagella. So this "irreducible complex" of 40 proteins has shrunk to 33 proteins, in the past 2 years of research! Behe's argument is that EVERY ONE of the 40 proteins are necessary. Obviously 7 of those 40 aren't completely necessary. Maybe it's only 30 or perhaps even 20 proteins that are absolutely necessary? It's hard to say, but it is very dangerous to make such dogmatic statements as "this system is irreducibly complex", especially when the system is made up of proteins that have other normal functions in the cell, apart from flagella - such as the GTPase proteins. For a more fair treatment of the subject of flagella (and bacteria and molecular evolution in general), I can happily recommend reading "The Outer Reaches of Life", by John Postgate (also available through Amazon.com), which is an excellent treatise about bacteria written for the "non-scientific reader".
Of course there is a need to explain the origins of biochemical complexity. But declaring "intelligent design by a miracle" to be this method is neither scientific nor helpful. I guess my advice would be similar to that of Huxley about Darwin's Origin of the Species - please read Behe's book and decide for yourself!
link to Amazon.com reviews link to Amazon.com's Evolution best-sellers
Back to Dave's CBS Homepage