Will our future as a species be shaped more by pressures for evolution or for extinction? A team of biologists at Washington State University reported in the journal Science their experimental evidence that chemical toxin damage from endocrine disrupters can be inherited, passing from one generation to another as a DNA modification. Such a process could turn out to be irreversible and threaten the long-term survival of any species.
This 2005 study shook the foundations of reproductive biology because the findings suggested another route for chemical toxins to trigger the onset of disease. Though this study was performed on rats, using a common insecticide normally sprayed on cropland and a fungicide used on vineyards (both suspected endocrine disrupters), it still may apply to humans if only because the principle demonstrated was so contrary to prevailing scientific opinion. Female rats were exposed in mid-gestation to the two chemicals, and 90 percent of their male offspring were born with low sperm counts and abnormal sperm production, while the other 10 percent were completely infertile. These patterns of male infertility were then passed down to the second-, third-, and fourth-generation males, none of whom were directly exposed to the toxins. It wasn’t a change in their DNA code but a change in the way their genes worked.
Equally disturbing, males descended from females exposed to the toxins were more susceptible to other diseases, especially prostate and kidney cancer. The implications for humankind fit the patterns we are seeing with infertility and disease. “You may develop a disease state even though you never had direct exposure,” concluded the study authors, “and you may pass it on to your great grandchildren.[“]
“This wasn’t supposed to happen,” marveled [researcher Michael] Skinner. He realized after replicating the results that a basic tenet of evolutionary biology—evolution proceeds by random genetic change—had just been overturned. No longer can we view the environment as having no direct influence on the traits we pass on to our children and grandchildren. Professor Skinner speculates that his findings may help to explain the dramatic rise in breast and prostate cancer in recent decades as a reflection of the cumulative effect of various toxins over several generations.
Fitzgerald, Randall. The Hundred-Year Lie: How to Protect Yourself from the Chemicals That Are Destroying Your Health (p. 165-66). Plume. Kindle Edition.