Saturday, October 03, 2009

Darwin's Dilemma: DVD Review

Darwin's Dilemma: The Mystery of the Cambrian Fossil Record is a documentary by Illustra Media exploring the Cambrian Explosion: the sudden appearance of major animal types in the fossil record. This review will provide an overview of the content.

As the Darwin's Dilemma website states:
Darwin’s Dilemma recreates the prehistoric world of the Cambrian era with state-of-the-art computer animation, and the film features interviews with numerous scientists, including leading evolutionary paleontologists Simon Conway Morris of Cambridge University and James Valentine of the University of California at Berkeley, marine biologist Paul Chien of the University of San Francisco, and evolutionary biologist Richard Sternberg, a Research Collaborator at the National Museum of Natural History.
The first quarter of the 72-minute DVD provides the historical background of the Burgess shale and describes the Cambrian Explosion as a mystery Darwin could not resolve. As Stephen Jay Gould put it: "Nothing distressed Darwin more than the Cambrian explosion." Paleobiologist Simon Conway Morris provides much of the narrative on the Cambrian, detailing the enormous diversification of fossils in the strata. This introduction provides an appropriate historical explanation of how this fossil layer was discovered and explored. Computer animations bring the fossilized animals to life, showing the full body plans and complexity of the most notable animals found in the Cambrian.

In the next fifteen minutes the documentary explores the development of Darwin's theory. This describes what Darwin expected to find in the fossil record, including step-by-step transitional forms. He was puzzled by not finding these transitions in the fossil record. However, he assumed the fossils were out there and that more time was needed to discover the transitional forms.

The documentary explains that according to contemporary estimates, some 90% of earth's history took place before Cambrian era. The Precambrian body plans were very simple, yet the Cambrian body-plans were much more complex. An analogy is provided: If 24 hours represents the history of the earth, at the 21st hour the major animal forms emerge in the span of 2 minutes, and are still will us today.

Half way through the documentary, further Cambrian fossils are discussed: the Chinese Chengjiang fossils, which were remarkably well preserved and many of them soft-bodied. Yet, they differed very little from the fossils found in other places in the world. In addition, small soft embryos were discovered in the Precambrian strata. If these can be preserved, why are other more complex forms found in the Precambrian strata? According to evolutionary biologist Rudolf Raff, "All of the known body plans seem to have appeared in the Cambrian radiation."

Three quarters through the documentary, young Darwin takes his voyage on the H.M.S. Beagle and the documentary describes Darwin's evolutionary model. It is described as simple to complex; gradual change over a long period of time. This view is described as "bottom-up," simple to complex.

The documentary makes the case that most of the major phyla first appear in the Cambrian strata. In the fossil record, the body plans don't gradually increase in complexity over time. The fossil record shows a sort of "top-down" model, with the phyla being established early and variations of those phyla following. This suddenness in the fossil record of the Cambrian is troublesome to Darwin. Yet, 150 years after Darwin, the same basic problem is still unsolved. Richard Dawkins is quoted: "Without gradualness… we are back to a miracle."


At the fifty-minute mark, the documentary begins to explore the structure of DNA. Just how much change in complexity is needed to create the diversity of body plans? Impressive computer animations show DNA while describing the mechanisms of mutation and natural selection. Next, Dawkins' idea of "climbing Mount Improbable" is illustrated: the idea of building a Cambrian animal one step at a time, one beneficial mutation at a time gradually over the course of a long period of time.

The documentary examines what sorts of mutations are needed to accomplish these transitions. And of probabilities? The probability of generating just one protein by mutation is about 1 in 10(74). This is compared to a blind man looking for one marked atom in our galaxy. In addition, the case is made that DNA mutations alone cannot make the necessary changes to the body plans themselves. To this point, the documentary has focused on showing the inadequacy of Darwin's theory to account for the fossil evidence or the DNA changes needed to produce the body plans found in the Cambrian strata.

At the one-hour point in the documentary, a case for intelligent design is more directly presented by looking at the information-rich qualities of the DNA instruction code for life. This case consists of a few main keys:
• Top-down pattern of appearance of the phyla
• Hierarchical arrangement of parts
• Absence of transitional fossils
• Information comes from intelligence
Each of these points is more fully developed in the last fifteen or so minutes of the documentary. It is not possible (nor the intention) of this review to lay out or defend the full case that is made in the DVD. Accordingly, the potential critic would be advised to view the DVD for himself.

In sum, the documentary is indeed a fascinating case for intelligent design. The production quality of the documentary is well on par with the first two DVDs in the Illustra Media series: The Privileged Planet and Unlocking the Mystery of Life, both of which are highly recommended. Get the DVD here. Learn more about the documentary here.

7 comments :

Stan McCullars said...

Nice review. Oddly enough, I ordered the DVD several hours ago from Amazon. Can't wait to get it!

Mark Lefers said...

Brian, did they talk about Hox genes or discuss new discoveries in EvoDevo? I'd recomend checking out this link.

Brian said...

Thanks for that link, Mark. I would encourage people to read it before watching the DVD.

Hox genes are not named, but eluded to regarding where body plan structure is determined.

Good to see you!

winteryknight said...

Don't forget about the the Icons of Evolution DVD.I think it's made by Coldwater Media.

greatcloud said...

Hey Brian,
Thanks for this good review! I'll link to it on CoW. I've had quite a bit of back and forth lately on Intelligent Design. I'm surprised at how strong people's feelings are on this issue. That might be an interesting post in itself -- why does ID raise such ire?

bossmanham said...

After reading the Talk.origins article presented by Mark, you can then read the response here.

Mark said...

After reading bossmanham comment pick up a college level biology book and get educated.

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