Analysis: Nature and nurture—not nature vs. nurture.

Whether ant or human, our genes and our environment collaborate to shape us

Science has moved beyond the old thought paradigm of nature vs. nurture as determinant of who we are.


Nature and nurture collaborate. Nature (inheritance) gives us our genes. Nuture (environment) plays a huge role in controlling gene behavior. And gene behavior is what guides us along the path of development from fertilized egg to fully functional adults—or something less than perfect if forces from the environment cause genes to behave inappropriately.

This video clip of ants provides a simple but powerful example. Florida carpenter ants exist in two forms: foragers (miners) vs. soldiers (majors). While they all share the same genes inherited from their parents, they differ profoundly in behavior because different genes are turned on (expressed) in the two different forms.

In these experiments, scientists at the University of Pennsylvania delivered chemicals into the brains of soldiers that turned on genes normally expressed in foragers. The soldiers began foraging, and continued to do so for more than a month.

A recent study of breast cancer genes in people gives an example of why this way of thinking is vital. It's long been known that mutant forms of the "breast cancer gene", called BRCA, interfere with the role of BRCA in repairing cell damage. If you inherit that mutant form, BRCA can't do what it normally does well—protect you from breast cancer.

It turns out that 'silencing' BRCA can do the same thing. If the gene can't be turned on (i.e., it is silenced), it can't be protective. Methylation is one epigenetic mechanism for preventing genes from being turned on. A molecular fragment called a methyl group binds to the gene in a way that prevents the gene from getting a wake up signal to do its tumor repair work.

This new study indicates that early-life exposure to the insecticide DDT increases methylation of BRCA. That will prevent the gene from doing its repair work. And the results are consistent with an earlier, epic epidemiological study by Barbara Cohn and her colleagues showing that women exposed to DDT in early life are almost four times more likely to develop breast cancer than those not exposed.

So, whether you are a Florida carpenter ant or a woman wondering about yesterday's biopsy, the factors that control how genes are turned on and off are central to your future.

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