One Long Argument:
One small primate helping to defend science education against the advance of neocreationism.
Tuesday, August 09, 2005
A prediction

Today the New York Times reports on a striking case of convergent evolution. It appears that two (relatively) unrelated groups of poison frogs - the poison-dart frogs of South America and the Mantella poison frog of Madagascar - independently came up with roughly the same convoluted way to be poisonous. Both dine on ants that produce toxic alkaloids, with the frogs storing the alkaloids in their skin sacs until some foolish creature decides on a frog dinner. Helping guard against the merely posthumous revenge of poisoning the one who ate you, both frogs have evolved bright coloration that serves as a warning. And don't forget the unsung heroes of this story, the little people (ok, insects) who make it all possible - the ants. In both cases, they also seem to have separately evolved the use of alkaloids, something rare among ants; researchers don't yet know what they do with them. (Interestingly, researchers found a single Madagascan frog that had nicotine in its system, without any apparent sources in the plants or insects sampled.)

So to recap: on two separate continents, different ants evolved the use of alkaloids (either from food or by making it themselves), then, two different groups of frogs evolved to not only eat the ants, but store the alkaloids, and then they both evolved bright warning colors and patterns. Indeed, the article points out close similarities in appearance.

It's amazing. It can't quite be called irreducible complexity, but it's pretty impressive. Indeed, I wouldn't be at all surprised to hear it being used as "evidence" against evolution, and for the idea of intelligent design. So, let me make a two-part prediction.

1) Within a reasonable time, scientists will develop a plausible, evidence-based hypothesis on how this specific case of convergent evolution happened. Again, evolutionary biology will prove to be a practical tool to help us understand the material world. For some, it will also add to an appreciation of our varied and astonishing world, whether evolution is seen as a purely materialistic practice or one set in motion (even untestably guided) by the Divine.

2) Intelligent design won't.

I'm fairly confident in (1), but maybe it won't come to pass. When it comes to (2), I'm certain. So let's see.

The Times:
As evolutionary biologists see it, the underlying principle of evolutionary convergence - that often there is one right tool for the job, and that selective pressures will reinvent the bio-utensil whenever the need arises - exemplifies just how non-random and ostensibly purposeful natural selection can be, and how readily it may be mistaken for evidence of supernatural "design."

The researchers see the nicotine-containing frog as "some of the most convincing evidence that plant-insect-frog toxin food chains do exist." It's astonishing to think about - the whole interlocking, interactive dance of change over time. Think of the all different factors in this small story, if that's accurate: plants evolving chemicals to protect against insects, ants evolving ways to use these chemicals and/or produce their own, frogs evolving the ability to eat the ants and store their poison. Now think of the effects on the different species: for example, ""Without the presence of the alkaloid ants . . . that nice little evolutionary niche of becoming diurnal and colorful would very likely never have opened up for the frogs." Now think of the effects on organisms interacting with them (including within this specific simplified food chain). Now think of . . .

Hold on, I'm getting dizzy. Off to read about the evolutionary history of frogs and ants. It's scandalous what I don't know . . .

posted by Dan S. on 9:31 AM |

"As this whole volume is one long argument, it may be convenient to the reader to have the leading facts and inferences briefly recapitulated . . ."
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The library (shelving in progress)
On The Origin of Species, by Charles Darwin
Chance in the House of Fate: A Natural History of Heredity, by Jennifer Ackerman
Tower of Babel: The Evidence against the New Creationism, by Robert T. Pennock
Intelligent Design Creationism and Its Critics: Philosophical, Theological, and Scientific Perspectives, by Robert T. Pennock (Ed.)
Finding Darwin's God: A Scientist's Search for Common Ground Between God and Evolution, by Kenneth R. Miller
Creationism's Trojan Horse: The Wedge of Intelligent Design, by Barbara Carroll Forrest and Paul R. Gross
At the Water's Edge : Fish with Fingers, Whales with Legs, and How Life Came Ashore but Then Went Back to Sea, by Carl Zimmer

Master Planned: Why intelligent Design Isn't, by H. Allen Orr, The New Yorker
Wedging Creationism into the Academy, by Barbara Forrest and Glenn Branch, Academe
The Faith That Dare Not Speak Its Name, by Jerry Coyne, The New Republic


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