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FAQ: The Cambrian Explosion Is Real, and It Is a Problem for Evolution

Photo: Trilobites, by Kevin Walsh [CC BY 2.0], via Wikimedia Commons.

An email correspondent who is friendly to intelligent design (ID) recently wrote us asking how to respond to common objections to ID arguments about the Cambrian explosion. He was engaged with an interlocutor was making all kinds of contradictory “throw everything at the wall and see what sticks” objections that were simply factually inaccurate and are belied by mainstream scientific experts.  

Stephen Meyer addressed these points in detail in Darwin’s Doubt with thoroughly researched arguments well backed by the scientific literature. This made it very easy to defend his arguments, which we’ve done across numerous articles here on Evolution News. The points made below by our friend’s interlocutor are simplistic and don’t reflect what leading Cambrian experts really think. But they are very common objections and so we compiled this FAQ to help address common misconceptions about the Cambrian explosion. 

Claim: “The Cambrian Explosion was not a geologically short event but really took millions of years. 

Response: “How ‘Sudden’ Was the Cambrian Explosion? Nick Matzke Misreads Stephen Meyer and the Paleontological Literature; New Yorker Recycles Misrepresentation

Claim: “There was complex animal life before the Cambrian so it does not represent the origin of many types of animals.”

Steve Meyer addressed this topic extensively in Chapters 2, 3, and 4 of Darwin’s Doubt, and Figure 2.5 in his book is a thoroughly researched and conservatively argued take on exactly how many animal phyla predate the Cambrian period and how explosive the Cambrian explosion was. Bottom line? At best only three animal phyla arose in the Precambrian and some twenty arose in the Cambrian period. But given problems with many claims of Precambrian animal fossils — especially bilaterian animals — the Cambrian period is probably even more explosive than that. For detail see:

Claim: “The Cambrian explosion is an artifact of an imperfect fossil record because in the Cambrian there are more fossil deposits to allow for soft-bodied fossils to be preserved, but these don’t exist in the Precambrian.

I addressed this in the latter link above which quotes Stephen Meyer writing the following in Darwin’s Doubt:

As Graham Budd and Sören Jensen state, “The known [Precambrian/Cambrian] fossil record has not been misunderstood, and there are no convincing bilaterian candidates known from the fossil record until just before the beginning of the Cambrian (c. 543 Ma), even though there are plentiful sediments older than this that should reveal them.” Thus they conclude, “The expected Darwinian pattern of a deep fossil history of the bilaterians, potentially showing their gradual development, stretching hundreds of millions of years into the Precambrian, has singularly failed to materialize.”

Claim: “The Cambrian explosion is an artifact of the fossil record because climatic or oceanic chemical changes allowed for a geologically-speaking rapid diversification in life.”

First, we need to understand that lots of new genetic information was needed for the animals that arose in the Cambrian explosion. See: 

Second, we need to understand that climatic/oceanic chemical changes don’t explain the origin of the information needed for Cambrian explosion. This is a very common argument and it doesn’t hold up — we’ve addressed it so many times it’s hard to find all the places! But here are a few: 

Claim: “The Cambrian explosion was not a real event and reflects a combination of many factors that make it appear as if animals appeared suddenly, but this really did not happen.”

This claim is not true and it is contradicted by many authorities on Cambrian paleontology and paleobiology:

I’ll close this little FAQ with a telling quote from Dutch biologist Martin Scheffer on the reality of the Cambrian explosion, from a Princeton University Press book:

The collapse of the Ediacaran fauna is followed by the spectacular radiation of novel life-forms known as the Cambrian explosion. All of the main body plans that we know now evolved in as little as about 10 million years. It might have been thought that this apparent explosion of diversity might be an artifact. For instance, it could be that earlier rocks were not as good for preserving fossils. However, very well preserved fossils do exist from earlier periods, and it is now generally accepted that the Cambrian explosion was real. 

Martin Scheffer, Critical Transitions in Nature and Society (Princeton University Press, 2009), 169-170.

There are of course other possible objections to Meyer’s arguments regarding the Cambrian explosion and we’ve probably addressed those somewhere too. But these are by far the most common objections — I hope this little FAQ is helpful in responding to them!