Saturday, 13 February 2010

Darwin's Dilemma Reviewed

From Professor Martin Brasier of Oxford;

The latest Intelligent Design film, called ‘Darwin’s Dilemma’, attempts to examine a problem that vexed poor Charles Darwin in 1859 – the puzzle of what we now call the ‘Cambrian explosion’. As an Oxford palaeontologist who has been working on this problem since 1966, I have been asked for my opinion on the veracity of its claims. Below are outlined some of what I take to be its more laughable misunderstandings.

1. The film makes a familiar mistake. There is a misplaced fixation upon beasts of the Burgess Shale. So antiquated is this view that the screenplay for this film could have been written by teachers in 1954, or even by Mack Sennett at Keystone studios in 1912, just after the Burgess Shale biota was first reported by Walcott. It needs to be remembered that the Burgess Shale appears far too late in the fossil record to tell us much about emergence of animals. Modern data shows that the explosion of modern phyla was beginning by about 545 Ma ago, with forms like Cloudina and Sabellidites. Since the Burgess Shale is a mere 505 Ma old, this gives us palaeontologists some 40 million years to play with. What a gift!

2. A rich fossil record of early animal remains has been discovered from near the end of the Ediacaran period at about 545 Ma to the appearance of calcified trilobites and echinoderms in the Chengjiang biota, some 520 Ma ago. This transitional period, variously known as the Tommotian or Fortunian Stage, contains examples of transitional forms. For example, Halkieria and Maikhanella are probable stem group ‘molluscs’ with multi-element shells; Eccentrotheca and Camenella are taken to be stem group ‘brachiopods’ with multi-element shells. Dozens of scientists have been writing about these materials in recent years. Some 20 million years of evolution has thereby been ignored. Or censored.

3. The first great mass extinction took place about 520 million years ago, during the Botomian and Toyonian Stages – well before the Burgess Shale. A rich diversity of reef building animals disappeared forever. These included archaeocyathan sponges and many small shelly fossils. But there is no mention of this. Did the film producers suffer amnesia at this point in the story? Or did that great prankster – the Intelligent Designer – make some big mistakes? If so, why call Her intelligent?

4. The film makes another common mistake. When Darwin referred to the need for many small steps in evolution, he did not say whether these steps had to be either fast or slow. Small steps can be made very quickly indeed – as with virus evolution today.

5. The film appears to have been shot within the walls of Cambridge University UK, with interviews taking place in the Sedgwick Museum, or around colleges such as St John’s and King’s College. Some think they perceive some blue highlights around the faces here, suggesting blue-screen shots in which the Cambridge settings have been imposed later. Whether real or false, this gives to the film a wholly spurious authority; rhe impression of a forgery.

For those interested, some of these evolutionary developments can be followed in my recent book on Darwin’s Dilemma, called Darwin’s Lost World (OUP, 2009), which takes the reader back from the Burgess Shale to the earliest multicellular organisms. Research into this fascinating interval remains wide open and is only just beginning. The Cambrian explosion was a real and entirely natural event, as was the wave of extinctions that followed. What a wonderful world!

H/T to Jerry Coyne

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