Wednesday, April 7, 2010
This is the second of two posts about the scientific process. Find the first post here.As he read the journal article describing Darwinius masillae, Chris Kirk couldn’t believe his eyes.
“The claims were so out there,” he said of the paper’s conclusions.
The basic claim was that the 47-million-year-old Darwinius fossil was a possible “missing link” between early primates and humans.
“One is that this is a rehash of an argument that really took place 20-30 years ago,” he said, “and for the last 15-20 years, for all intents and purposes, has been settled among people who study primate evolution.”
Also surprising was the way the news was rolled out.
The journal paper appeared simultaneously with a book and a History Channel program. The announcement was made at a press conference at the American Museum of Natural History with New York City Mayor Michael Bloomberg participating. The only people missing were Ben Stiller and other cast members from “Night at the Museum.”
The Darwinius unveiling generated a bit of a reaction among physical anthropologists.
“There were a couple of days of furious e-mailing back and forth,” Kirk said.
The upshot was that he and colleagues from Duke University and the University of Chicago would write a point-by-point critique of the Darwinius paper.
Their response, which became two papers, said the Darwinius fossil was an early member of lemur and loris lineage of primates and not the monkey-ape-human lineage.
Kirk said it was important to him and his colleagues that their paper to be peer reviewed, that it stand up to the scrutiny of other scientists.
“That’s the ultimate check, that’s what makes the scientific literature different from any other literature,” he said.
The editor at PLoS One, where the Darwinius paper was published, suggested they respond in the online comments section.
That’s not quite what Kirk and his colleagues were looking for. They wanted peer review a bit more rigorous than online comments provide.
They found a home for their responses in the Journal of Human Evolution.
The Darwinius episode shows how the scientific process works and, in particular, how it rights itself if it breaks down.
“I see this as part of the inevitable correction that was bound to come, given the extraordinary claims that were made about the evolutionary relationships of Darwinius on the basis of very little evidence,” Kirk said. “I think it’s encouraging, too, that you may be able to publish something unorthodox, but it’s not going to last long if you can’t provide empirical data to support your claim. Ultimately, papers die a death in the scientific literature because nobody cites them anymore.”
The thing is, Kirk said, is that the Darwinius fossil is important as part of the loris-lemur lineage.
“The major problem, and the major reaction, was about the conclusions about the evolutionary relationships, them saying without any good evidence that Darwinius, (here he starts talking n headline tones) ‘Overturns All Our Previous Views, This Fossil, In One Fell Swoop Demonstrates That The Entire Group Of Primates That Darwinius Belongs To, Called The Adapiforms, Is Actually On The Monkey, Ape And Human Lineage Instead Of The Lemur And Loris Lineage.’ ”
Again, it comes down to evidence.
“You can say anything you want, no matter how crazy it is, provided that you have good evidence to back it up,” he said. “That’s your minimum criterion. You need to be relying on an established body of published literature or you need to be presenting new evidence.”