What Is Darwin’s Dilemma?

“Darwin’s dilemma” refers to Charles Darwin’s bafflement that the fossil record contradicted what his theory of evolution predicted. In his classic book On the Origin of Species, Darwin declared that if his theory of evolution were true “it is indisputable that before the lowest Cambrian stratum was deposited… the world swarmed with living creatures.” Yet Darwin admitted that the fossil record below the Cambrian strata seemed to be bereft of such creatures. Instead “species belonging to several of the main divisions of the animal kingdom suddenly appear in the lowest known fossiliferous rocks”—without any evidence of prior ancestral forms. Darwin frankly acknowledged that this lack of ancestral forms was “a valid argument” against his theory. But he hoped that time—and more research—would provide the evidence that was lacking. Some 150 years later, the documentary Darwin’s Dilemma probes how Darwin’s dilemma has been aggravated—not resolved—by the last century of fossil discoveries, starting with the strange and wonderful creatures uncovered a century ago in the Burgess shale in British Columbia, Canada.

Darwin’s Dilemma in Darwin’s own words:

On the sudden Appearance of Groups of allied Species in the lowest known Fossiliferous Strata.

There is another and allied difficulty, which is much more serious. I allude to the manner in which many species in several of the main divisions of the animal kingdom suddenly appear in the lowest known fossiliferous rocks. Most of the arguments which have convinced me that all the existing species of the same group are descended from a single progenitor, apply with nearly equal force to the earliest known species. For instance, it cannot be doubted that all the Silurian trilobites are descended from some one crustacean, which must have lived long before the Silurian age, and which probably differed greatly from any known animal. Some of the most ancient Silurian animals, as the Nautilus, Lingula, &c., do not differ much from living species; and it cannot on our theory be supposed, that these old species were the progenitors of all the species belonging to the same groups which have subsequently appeared, for they are not in any degree intermediate in character.

Consequently, if the theory be true, it is indisputable that, before the lowest Silurian or Cambrian stratum was deposited long periods elapsed, as long as, or probably far longer than, the whole interval from the Cambrian age to the present day; and that during these vast periods the world swarmed with living creatures…

To the question why we do not find rich fossiliferous deposits belonging to these assumed earliest periods, I can give no satisfactory answer… the difficulty of assigning any good reason for the absence beneath the Upper Cambrian formations of vast piles of strata rich in fossils is very great. It does not seem probable that the most ancient beds have been quite worn away by denudation, or that their fossils have been wholly obliterated by metamorphic action, for if this had been the case we should have found only small remnants of the formations next succeeding them in age, and these would always have existed in a partially metamorphosed condition. But the descriptions which we possess of the Silurian deposits over immense territories in Russia and in North America, do not support the view, that the older a formation is, the more it has invariably suffered extreme denudation and metamorphism.

The case at present must remain inexplicable; and may be truly urged as a valid argument against the views here entertained. [emphasis added]

—Chapter IX, “On the Imperfection of the Geological Record,” On the Origin of Species, fifth edition (1869), pp. 378-381.

The Mystery of the Cambrian Explosion

Darwin’s Dilemma explores one of the great mysteries in the history of life: the “Cambrian Explosion,” the geologically-sudden appearance in the fossil record of most major animal phyla during a span of less than ten million years. The Cambrian Explosion, which took place about 530 million years ago, provides a major challenge to the traditional mechanisms of Darwinian evolution. In the words of one evolutionary biologist: “The extreme speed of anatomical change and adaptive radiation during this brief time period requires explanations that go beyond those proposed for the evolution of species within the modern biota.” (R. L. Carroll, “Towards a new evolutionary synthesis,” Trends in Ecology and Evolution, Vol. 15(1):27-32 (2000))

Darwin’s Dilemma provides a tantalizing glimpse into the world of the Cambrian explosion through computer animation and  the amazing fossils in the Burgess Shale of British Columbia, Canada and the Maotianshan shales of Chengjiang, China.

Download the FAQ: Questions about the Cambrian Explosion, Evolution, and Intelligent Design

For a discussion and study guide of Darwin’s Dilemma, see Darwin’s Dilemma Discussion and Study Guide, by Ryan Huxley of the IDEA Center.

To discover more about the ideas, people, and places discussed in Darwin’s Dilemma, use the resources below.

Resources on the Cambrian Explosion
“The Scientific Controversy over the Cambrian Explosion” (Briefing Paper)

Casey Luskin, “BioEssays Article Admits ‘Materialistic Basis of the Cambrian Explosion’ is ‘Elusive,’” Evolution News and Views (June 24, 2009)

Casey Luskin, “Trails of Microorganisms Discovered on Ocean-Bottom Knock Down Favorite Darwinist Argument Against Cambrian Explosion,” Evolution News and Views (Dec. 14, 2008)

Stephen Meyer, “The origin of biological information and the higher taxonomic categories,” Proceedings of the Biological Society of Washington (2004). For detailed information on the controversy that followed the publication of this peer-reviewed technical paper, visit the Smithsonian Controversy web page.

Stephen Meyer, Marcus Ross, Paul Nelson & Paul Chien, “The Cambrian Explosion: Biology’s Big Bang,” Darwinism, Design, and Public Education (Michigan State University Press, 2004)

On the Origin of Phyla: An Interview with James Valentine

Simon Conway Morris, “Darwin’s dilemma: the realities of the Cambrian ‘explosion,’” Philosophical Transactions of the Royal Society (2006)

The Cambrian Explosion (Virtual Fossil Museum)

“Evolution’s Big Bang,” Time magazine cover story on the Cambrian Explosion (Dec. 4, 1995)

Resources on the Fossils of the Burgess Shale
“The Burgess Shale: Evolution’s Big Bang” Online Exhibit

The Burgess Shale (Smithsonian Institution National Museum of Natural History)

Charles Walcott and the Burgess Shale

The Panoramic Photographs of Charles D. Walcott

Resources on the Fossils of Chengjiang, China
Chengjiang China Fossils—“A Window to the Cambrian Explosion” (Virtual Fossil Museum)

Fred Heeren, “Challenging Fossil of a Little Fish,” The Boston Globe (May 30, 2000)

Fred Heeren, “Paleontologic Agitprop?” Insight on the News (July 24, 2000)

Investigating Evolution: The Cambrian Explosion, pt. 1

Investigating Evolution: The Cambrian Explosion, pt. 2