Our Chemical Inheritance

In a half-hearted attempt to organize my internet bookmarks this morning I found, for some unexplainable reason, ten or so bookmarks for the same article. I don’t recall bookmarking the page more than once, but somehow it seems to be cloning itself. Since it’s trying so hard to get my attention, I think I’ll pay it some by summarizing it here, even though I’ve touched on the issues it discusses previously.

The article, entitled “The Toxins that Affected Your Great-Grandparents Could be in Your Genes," was published in Smithsonian magazine. It makes the following points:

• In 2005, a researcher who worked with biologist Michael Skinner botched an experiment. The two were studying the effects of a fungicide on fetal development in rats and the researcher accidentally bred the grandchildren of the original subjects.

• When the new rats (the fourth generation of the rats who were originally exposed to the chemical) were analyzed, it was discovered that the animals had sperm defects, but that this was not due to a change in their inherited DNA.

• The experiment was repeated many times with different rats, different chemicals, and different health effects. The pattern held that diseases related to chemical exposures showed up in the fourth and fifth generations. One pattern found was that subsequent generations of rats exposed to DDT were more likely to be obese.

• It has long been known that an altered DNA message can be passed on to future generations. In Skinner’s rats, however, the disease process was found to be related to altered patterns of molecules called methyl groups. The author notes, “like burrs stuck to a knit sweater, these methyl molecules interfered with the functioning of the DNA and rode it down through future generations, opening each new one to the same diseases.”

• The discovery spawned a new field, which has come to be called transgenerational epigenetics.

• The “burrs” apparently fasten themselves in a particular arrangement, so that the biological fingerprint of the chemical may be traceable. In the future, it may be possible for doctors to screen people for methylation patterns in order to determine the chemical exposures of previous generations.

• Skinner’s findings have been opposed by “moneyed interests” and by those still attached to the old genetic paradigm. Skinner responds by saying that “the best way to handle these things is to let the science speak for itself."

The science is speaking. Are we listening?