"Transgenerational epigenetic inheritance is an area of much controversy," says Emma Whitelaw, a scientist at the University of Adelaide, who was not involved in the research. "This study will stimulate researchers working with other model organisms to take the notion of transgenerational epigenetic inheritance more seriously."

It's not yet clear how broadly the longevity findings will apply. Like C. elegans, animals from yeast to humans have a version of ASH-2. However, much of the aging research in invertebrates has yet to be replicated in more complex animals.

This is not the first time scientists have shown that an acquired trait can be transmitted across generations, as Jean-Baptiste Lamarck postulated two centuries ago. A 2003 study showed that when a female mouse eats DNA-methylating foods, it affects her progeny's fur color and other traits. A 2010 paper found that when male mice ate high-fat diets, it made their daughters fatter and gave them type 2 diabetes. Another 2010 paper found that changing the cholesterol metabolism in male mice through diet altered their offspring's cholesterol and lipids. In each case, no DNA mutations were involved—only a trait that the parent acquired and passed on. Whitelaw calls it "a molecular memory of the parent's experience."