|Stephen Jay Gould|
By Nicholas Wade, The New York Times, June 13, 2011
Scientists have often been accused of letting their ideology influence their results, and one of the most famous cases is that of Morton’s skulls — the global collection amassed by the 19th-century physical anthropologist Samuel George Morton.
In a 1981 book, “The Mismeasure of Man,” the paleontologist Stephen Jay Gould asserted that Morton, believing that brain size was a measure of intelligence, had subconsciously manipulated the brain volumes of European, Asian and African skulls to favor his bias that Europeans had larger brains and Africans smaller ones.
But now physical anthropologists at the University of Pennsylvania, which owns Morton’s collection, have remeasured the skulls, and in an article that does little to burnish Dr. Gould’s reputation as a scholar, they conclude that almost every detail of his analysis is wrong.
“Our results resolve this historical controversy, demonstrating that Morton did not manipulate his data to support his preconceptions, contra Gould,” they write in the current PLoS Biology.
Dr. Gould, who died in 2002, based his attack on the premise that Morton believed that brain size was correlated with intelligence. But there is no evidence that Morton believed this or was trying to prove it, said Jason E. Lewis, the leader of the Pennsylvania team. Rather, Morton was measuring his skulls to study human variation, as part of his inquiry into whether God had created the human races separately (a lively issue before Darwin decreed that everyone belonged to the same species).
In his book, Dr. Gould contended that Morton’s results were “a patchwork of fudging and finagling in the clear interest of controlling a priori convictions.” This fudging was not deliberate, Dr. Gould said, but rather an instance of unconscious doctoring of data, a practice he believed was “rampant, endemic and unavoidable” in science. His finding is widely cited as an instance of scientific bias and fallibility.
But the Penn team finds Morton’s results were neither fudged nor influenced by his convictions. They identified and remeasured half of the skulls used in his reports, finding that in only 2 percent of cases did Morton’s measurements differ significantly from their own. These errors either were random or gave a larger than accurate volume to African skulls, the reverse of the bias that Dr. Gould imputed to Morton.
“These results falsify the claim that Morton physically mismeasured crania based on his a priori biases,” the Pennsylvania team writes.
Dr. Gould did not measure any of the skulls himself but merely did a paper reanalysis of Morton’s results. He accused Morton of various subterfuges, like leaving out subgroups to manipulate a group’s overall score. When these errors were corrected, Dr. Gould said, “there are no differences to speak of among Morton’s races.”
But Dr. Gould himself omitted subgroups in his own reanalysis, and made various errors in his calculations. When these are corrected, the differences between the racial categories recognized by Morton are as he assigned them. “Ironically, Gould’s own analysis of Morton is likely the stronger example of a bias influencing results,” the Pennsylvania team writes.
Dr. Lewis, the lead author, said that on checking the references for some of Dr. Gould’s accusations he found that Morton had not made the errors attributed to him. “Those elements of Gould’s work were surprising,” he said. “I can’t say if they were deliberate.”
Dr. Lewis, who is now at Stanford University, began the project while at Penn.
An earlier study by John S. Michael, then an undergraduate at Penn, concluded that Morton’s results were “reasonably accurate,” with no clear sign of manipulation. But when others suggested Dr. Gould had been refuted, Philip Kitcher, a philosopher of science at Columbia University, rode to his defense.
“It is not entirely evident that one should prefer the measurements of an undergraduate to those of professional paleontologist,” he wrote in 2004. “Pending further measurement of the skulls and further analysis of the data, it seems best to let this grubby affair rest in a footnote.”
Dr. Kitcher said last week that the Penn team had done a “very careful job” and that “it’s a nice thing that undergraduate work gets vindicated.”
As for the new finding’s bearing on Dr. Gould’s reputation, Dr. Kitcher said: “Steve doesn’t come out as a rogue but as someone who makes mistakes. If Steve were around he would probably defend himself with great ingenuity.”
But Ralph L. Holloway, an expert on human evolution at Columbia and a co-author of the new study, was less willing to give Dr. Gould benefit of the doubt.
“I just didn’t trust Gould,” he said. “I had the feeling that his ideological stance was supreme. When the 1996 version of ‘The Mismeasure of Man’ came and he never even bothered to mention Michael’s study, I just felt he was a charlatan.”