I may be a bit late to the party, but I’ve finally gotten a chance to read Stephen Meyer’s latest book, Darwin’s Doubt. Having read his previous book, Signature in the Cell, I had high expectations, and Meyer did not disappoint. Darwin’s Doubt takes a look at the longstanding enigma of the Cambrian explosion – a very brief time in history in which the majority of all major animal forms abruptly appear in the fossil record with no trace of simpler ancestral forms. Darwin recognized the problem the Cambrian fossils posed to his theory, but thought future discoveries would solve the problem. After 150 years, the problem hasn’t been solved. Instead, it’s been made more acute.
Scientists are increasingly coming to recognize that Darwin’s theory cannot explain the Cambrian explosion. Some are proposing alternative, naturalistic explanations. Others see the Cambrian explosion as powerful evidence for the intervention of an Intelligent Designer nearly 550 million years ago. Who’s right? Darwin? The Darwin doubters? Intelligent Design theorists? Stephen Meyer walks the reader through the evidence, and then evaluates competing explanations to see how they stack up against the evidence. It should be no surprise to those who know Stephen Meyer where the book concludes. The question is how he gets to his conclusion.
What follows is a roughly chapter-by-chapter summary of Meyer’s argument that I will post over the course of several days. It does not do the book justice, but it’s a start. Read my summary, and then buy the book. Even if you don’t agree with Intelligent Design, Darwin’s Doubt will help you better understand what needs to be explained, the current state of the field, and the latest discoveries in paleontology and developmental biology. Meyer is a master storyteller and great at making difficult scientific ideas easy to digest.
Though Darwin offered a very compelling and systematic argument for unguided, macroscopic biological change over time, one piece of evidence in particular did not gel well with his theory – the fossil record contained in the Pre-Cambrian and Cambrian strata – and paleontologists were not shy about pointing that out. The Cambrian period began 544 MYA (million years ago). An explosion of animal life appears in the record starting 530 MYA and lasts 10 MY, with the largest explosion of animal phyla occurring in the first 5-6 MY (which is just 1/10 of 1% of the earth’s history). During this 5-6 MY period, at least 16 phyla and 30 classes of animals make their first appearance. Strangely, we find no ancestors to this vast array of organisms in the Pre-Cambrian strata.
Darwin acknowledged that the early fossil evidence did not support his theory, but thought the problem was that ancestors to the Cambrian animals and the intermediate forms that followed were either not preserved, or just not found yet (“artifact hypothesis”).
The discovery of the Burgess Shale in 1909 did not help Darwin’s case, but offered further evidence against it. Many more Cambrian animals were discovered (with no Pre-Cambrian ancestors), further illuminating just how diverse and complex the Cambrian animals were. The pattern of the fossil record was shown to be the exact opposite of what we would expect to find if Darwin’s theory was true. If change comes about through descent with modification from a common ancestor, with small changes adding up into bigger changes over time, we should expect the number of phyla in the Cambrian to be relatively few, with more and more phyla being added over time. Instead, almost all known phyla appear in the Cambrian. Some of those phyla have died out over the years, and a couple have appeared since then, but the majority of all phyla are present at the base of the tree, not the top, and those Cambrian phyla show no evidence of ancestors. Instead of seeing an exponential increase of new phyla over the last 500 MY, we simply see the diversification of the Cambrian phyla into more and more distinct examples of that phyla. So Darwin’s depiction of the tree of life is exactly the opposite of what we find in the fossil record. You might say it is upside down.
Jeffrey Schwartz (University of Pittsburgh) explains the predicament the Cambrian explosion puts Darwinists in: “We are still in the dark about the origin of most major groups of organisms. They appear in the fossil record as Athena did from the head of Zeus – full-blown and raring to go, in contradiction to Darwin’s depiction of evolution as resulting from the gradual accumulation of countless infinitesimally minute variations.”
Jeffrey Schwartz, Sudden Origins: Fossils, Genes, and the Emergence of Species (New York, Wiley, 1999), 3, as quoted in Meyer, 318.