Darwin revisited

January 10, 1995

Is there any scientific basis for the familiar aphorism "like father, like son"? Apparently there's some truth to the observation that children resemble their parents in ways that involve more than just genes. Researchers in Israel recently have come up with an intriguing new twist on the ancient nature vs. nurture debate, one that may apply to a wide variety of situations, from nurturing musical talent in the very young to breaking the cycle of welfare dependency.

Dr. Eva Jablonka of Tel Aviv University and Dr. Eytan Avital of the department of natural sciences at David Yelin Teacher's College in Jerusalem have proposed that many species, including humans, transmit characteristics from one generation to the next not simply by passing along their genes, but also by training their offspring to behave as they do so thoroughly that the behavior is passed down from generation to generation without any involvement of DNA, the complex genetic material in which inherited traits are encoded.

The researchers call their idea "phenotypic cloning," a process by which parents impress their ways of doing things on their offspring so firmly that the behaviors -- or phenotypes -- appear to have the strength of genetically inherited traits.

In this view, natural selection still operates to favor the survival of the best behaviors, while less adaptive ones get tossed out of the phenotype pool. But the model differs from traditional Darwinian theory in that differences in behavior need not imply an underlying genetic variation but rather may be acquired through learning.

That twist may make the new model useful in understanding a variety of social phenomena. It may, for example, help explain how the Bach family dominated musical life in Germany for more than 200 years, even though it seems unlikely that there is any such thing as a "music gene." Or why some dysfunctional behaviors, such as child and spousal abuse, appear to run in families.

It could also prove useful in understanding the persistence of social ills like school failure, teen pregnancy and welfare dependence, which frequently cross generational lines. And it should cast new light on the recurring debate over the relationship between genetics and intelligence -- recently revived by Charles Murray and Richard Herrnstein's "The Bell Curve." The argument over nature vs. nurture may never be settled definitively. But the new view of evolutionary processes strongly suggests there is more to heredity than just genes.

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