Female rats avoid males whose great-grandfathers were exposed to a common fruit crop fungicide. Researchers from the University of Texas at Austin examined rats whose great-grandparents were exposed to the fungicide vinclozolin, which causes early onset of cancer and kidney disease in males.
Female rats can tell the difference between male descendants of rats that have or have not been exposed to vinclozolin, and strongly prefer males descended from unexposed rats. Proving for the first time that environmental contamination affects evolution through changes in mating behavior.
Vinclozolin causes changes in the male rats' germline cells, like sperm. It doesn't directly alter DNA, instead causing changes in elements that regulate DNA. This is known as an epigenetic change.
Early onset of disease caused by initial exposure to vinclozolin is passed down generation to generation through the germline of the males. The female rats can sense something is wrong, even though they can't see it. Since males move beyond their birth territory when they mature, they carry their unlovable and fatal defects with them.