The shiftlessness of scientific paradigms

Sharon Begley, the science writer, has a must-read piece in the Newsweek issue dated January 12th that was published online on January 3rd.  It’s chiefly about the resistance to change of scientific paradigms.  Her starting point is a collection of essays in which scientists answer the question posed in the title of the book, What Have You Changed Your Mind About? Begley is disappointed that most of the changes reflect shifts in opinions or values — they do not comprise reversals of positions on contentious matters.

Rare, however, are changes of mind by scientists identified with either side of a contentious issue. No one who rose to fame arguing that Alzheimer’s disease is caused by sticky brain plaques and who has now been convinced by evidence that the plaques are mostly innocent bystanders, not culprits. No one who once pushed hormone replacement therapy to prevent heart attacks in menopausal women who now realizes that the drugs increase the risk of heart attacks (as well as stroke and breast cancer). No one who cast his lot with the theory that a killer asteroid sent the dinosaurs into extinction who now reads the impact-crater evidence as implicating worldwide volcanism instead. But really, we shouldn’t be surprised. Proponents of a particular viewpoint, especially if their reputation is based on the accuracy of that viewpoint, cling to it like a shipwrecked man to flotsam. Studies that undermine that position, they say, are fatally flawed.

And, she highlights those essays by scientists who have shifted their positions.

The few essays in which scientists do admit they were wrong— and about something central to their reputation—therefore stand out. Physicist Marcelo Gleiser of Dartmouth breaks ranks with almost every physicist since Einstein, and with his own younger self, in now doubting that the laws of nature can be unified in a single elegant formulation. Gleiser has written dozens of papers proposing routes to the unification of gravity and quantum mechanics through everything from superstrings to extra dimensions, but now concedes that “all attempts so far have failed.” Unification may be esthetically appealing, but it’s not how nature works.

The most fascinating backpedaling is by scientists who have long pushed evolutionary psychology. This field holds that we all carry genes that led to reproductive success in the Stone Age, and that as a result men are genetically driven to be promiscuous and women to be coy, that men have a biological disposition to rape and to kill mates who cheat on them, and that every human behavior is “adaptive”—that is, helpful to reproduction. But as Harvard biologist Marc Hauser now concedes, evidence is “sorely missing” that language, morals and many other human behaviors exist because they help us mate and reproduce. And Steven Pinker, one of evo-psych’s most prominent popularizers, now admits that many human genes are changing more quickly than anyone imagined. If genes that affect brain function and therefore behavior are also evolving quickly, then we do not have the Stone Age brains that evo-psych supposes, and the field “may have to reconsider the simplifying assumption that biological evolution was pretty much over” 50,000 years ago, Pinker says. How has the view that reproduction is all, and that humans are just cavemen with better haircuts, hung on so long? “Even in science,” says neuroscientist Roger Bingham of the University of California, San Diego, “a seductive story will sometimes … outpace the data.” And withstand it, too.

(H/T: Stephanie West Allen)

Advertisements