Monday, December 28, 2009


Venomous dinosaurs? How scientists disagree.

One criticism of science that we often hear is...


You know, criticism of science is still a phrase that seems odd to me. When I was growing up, we never thought to criticize science, in general. Of course, there’d be things that scientists got wrong, and we were critical of those as individual items. But that, we knew, is how science is — we’re always learning new things about what we thought we knew. It’s a strength of science.

Science was what had been moving us forward, and would continue to do. In the “space age”, we could thank science for advances like safer, more efficient transportation; better medical knowledge and, thus, better health and longer life; radio and television; worldwide communication. We never thought to criticize science as a whole.

But such criticism seems fashionable now, in a world where many arm for a battle of God versus science, where some consider the quest for knowledge to be evil, where a president convinced us that applying new information and revising our analysis is a weakness rather than a strength.

And so, one criticism of science that we often hear is that scientists disagree and fight with each other about what the truth is. Scientists, these critics say, don’t know, and can’t agree on what their findings mean.

We ran across an example of that last week, with a report from David Burnham, a University of Kansas paleontologist. Dr Burnham and his colleagues have been studying the teeth of a dinosaur called Sinornithosaurus, and have found grooves in some of the upper teeth. Their study led them to the hypothesis that Sinornithosaurus was venomous, and the grooves were channels that delivered the poison, incapacitating the animals’ prey.

They have reasons other than the grooves alone for coming to that conclusion — other structures in the jaw, and comparisons with modern venomous animals could support their idea.

Of course, some scientists, also experts in the field, have come out in disagreement with Dr Burnham’s thesis:

The announcement of a new kind of dinosaur, especially one so radically endowed, usually brings out some skeptics. Paleontologist Tom Holtz of the University of Maryland says he’s not convinced yet. “They give a number of different physical features that they interpret as signs of poison or poison delivery systems,” says Holtz, who is an expert in carnivorous dinosaurs, “but which, in my opinion, are more easily interpreted in other types of biological contexts.”

And here we have the normal scientific debate, where challenges to the hypothesis are made, alternative explanations for the observed data are proffered, and the experts analyze and re-analyze what they have, looking for other items that support or refute one explanation or another.

For example, Holtz says many dinosaurs have a cavity in their jawbone, but it’s thought to have held an air sac for cooling. He says the grooves could be something else, maybe wear and tear. Holtz adds that he wouldn’t be terribly surprised if it turned out that Sinornithosaurus was venomous; he just doesn’t think the Burnham paper provides enough evidence yet.

Note that Dr Holtz does not say that Dr Burnham is wrong; it’s too early to determine that. He acknowledges that Dr Burnham could be right, but presses him with challenges that must be met first. Now that the preliminary data and hypothesis are out, there’s more study needed to see where it goes.

But Burnham says he has found more fossils in China with grooved teeth. And when he goes back to China, he says, he’ll be looking at dinosaur teeth a lot more closely than he used to.

That’s how science works. We argue with each other until we’re convinced that the explanations we have for the data we see are correct, to the best of the knowledge and information we have so far.

It’s what keeps science strong, honest, and real.

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