DON'T STOP BELIEVIN':

Moonshine: Why the Peppered Moth Remains an Icon of Evolution (Matt Young, February 11, 2004, Department of Physics, Colorado School of Mines)

What did Kettlewell do, and why does Hooper think he fudged his data? Beginning in the mid-1800's, successive generations of peppered moths (Biston betularia) in Britain gradually darkened in response to the air pollution in the industrialized parts of the country. Specifically, a genetically determined dark, or melanic, form of the moth replaced the lighter form as industrial pollution killed lichens on the barks of trees and also coated the bark with a layer of soot. [...]

I will discuss only the release-recapture experiments reported in (Kettlewell 1955), because these are the experiments that are under fire and because (unlike Kettlewell's critics) we can bring quantitative tools to bear. [...]

Hooper has noted that the number of recaptures increased sharply on 1 July, the same day that E. B. Ford sent a letter to Kettlewell. Ford's letter commiserated with Kettlewell for the low recapture rates but suggested that the data would be worthwhile anyway. The letter is unremarkable, and two facts militate against a finding of fraud. First, Kettlewell finished collecting data in the wee hours of the morning and therefore could not have received the letter before collecting his data on 1 July. He markedly increased the number of moths he released on 30 June, the day before the letter was mailed, not 1 July. Additionally, as Hooper admits, he continued to release more moths after 30 June. Not surprisingly, he also captured more moths: more moths released, more captured.

Make that: more captures reported.

Posted by Orrin Judd at June 6, 2005 9:51 AM