Those three words often separate the scientific pros from the posers

My friend James Randi speculates — with only partial facetiousness — that when one receives a Ph.D., a chemical secreted from the diploma parchment enters the brain and prevents the recipient from ever again saying “I don’t know” and “I was wrong.” As one counterexample I hereby confess that in my column on Chinese science in the July issue I was wrong in my conversion of Chinese yuan as 80 to the dollar (it is eight).

More serious was a statement I made in the June issue about a Fox television program claiming that the moon landing was faked. I said that the lunar lander rocket showed no exhaust because there is no oxygen-rich atmosphere on the moon. I was partially wrong. The lack of an atmosphere plays a minor role; the main reason is that the lander’s engine used hypergolic propellants that burn very cleanly. In both instances, readers were kind enough to provide constructive criticism.

Critical feedback is the lifeblood of healthy science, as is the willingness (however begrudgingly) to say “I was wrong” when faced with persuasive evidence. It does not matter who you are or how important you think your idea is — if it is contradicted by the evidence, it is wrong. In contrast, pseudoscientists typically eschew the peer-review process in order to avoid the inevitable critical commentary. Consider Immanuel Velikovsky’s controversial theory about planetary collisions, first proffered in 1950. Velikovsky was not a scientist, and he rejected the peer-review process after submitting a paper to the prestigious journal Science: “My [paper] was returned for rewriting after one or two reviewers took issue with my statement that the lower atmosphere of Venus is oxidizing. I had an easy answer to make …

but I grew tired of the prospect of negotiating and rewriting.”

Nearly a quarter of a century later, after a special session devoted to his theory was organized by Carl Sagan at the 1974 AAAS meeting, Velikovsky boasted, despite all the errors and mistakes that experts had identified in his book, that “my Worlds in Collision as well as Earth in Upheaval do not require any revisions, whereas all books on terrestrial and celestial science of 1950 need complete rewriting … and nobody can change a single sentence in my books.” Unwillingness to submit to peer review and inability to admit error are the antitheses of good science.

A splendid example of honorable science can be found in the May 11 issue of Science, in a report on the “African Origin of Modern Humans in East Asia.” A team of geneticists took samples from 12,127 men from 163 Asian and Oceanic populations, tracking three genetic markers on the Y chromosome. They discovered that every one of their subjects carried a mutation at one of those three sites that can be traced back to a single African population some 35,000 to 89,000 years ago. Their paper marks a major victory for the “Out of Africa” hypothesis that all modern people can trace their heritage to Africa. It is also a significant blow to the “Multiregional” hypothesis that modern human populations have multiple origins dating back many hundreds of thousands of years.

One of the chief defenders of Multiregionalism, anthropologist Vincent M. Sarich of the University of California at Berkeley, is well known for his vigorous and energetic defense of his beliefs and theories. (I know Vince and can attest that he is a tenacious fighter.) Yet when this self-proclaimed “dedicated Multiregionalist” saw the new data, he confessed in Science: “I have undergone a conversion — a sort of epiphany. There are no old Y chromosome lineages [in living humans]. There are no old mtDNA lineages. Period. It was a total replacement.” In other words, in a statement that takes great intellectual courage to make, Sarich said that he was wrong. Whether he is right to have converted remains to be seen, as additional studies confirm or belie the findings.

The point is that creationists and social critics who decry science as dogmatic obedience to authority and an old-boys network of closed-minded fogies are simply mistaken. Science is in constant flux, theories are batted about by the ever shifting winds of evidence, and scientists really do change their minds.

Of course, I could be wrong…