Acquired Inheritance in Response to Starvation
In recent years researchers have discovered that the metabolic response to calorie restriction can extend into following generations, passed along via epigenetic and other mechanisms. The metabolism of descendant individuals is altered from the norm even when they never experience calorie restriction themselves. Data on this effect is harder to establish for humans in comparison to short-lived laboratory species, but it does exist:
Evidence from human famines and animal studies suggests that starvation can affect the health of descendants of famished individuals. Starving women who gave birth during the famine had children who were unusually susceptible to obesity and other metabolic disorders, as were their grandchildren. Controlled animal experiments have found similar results, including a study in rats demonstrating that chronic high-fat diets in fathers result in obesity in their female offspring. But how such an acquired trait might be transmitted from one generation to the next has not been clear.[Researchers] starved roundworms for six days and then examined their cells for molecular changes. The starved roundworms, but not controls, were found to have generated a specific set of small RNAs. (Small RNAs are involved in various aspects of gene expression but do not code for proteins.) The small RNAs persisted for at least three generations, even though the worms were fed normal diets. The researchers also found that these small RNAs target genes with roles in nutrition.
Since these small RNAs are produced only in response to starvation, they had to have been passed from one generation to another. "We know from other studies that small RNAs can be transported from cell to cell around the body. So, it's conceivable that the starvation-induced small RNAs found their way into the worms' germ cells - that is, their sperm or eggs. When the worms reproduced, the small RNAs could have been transmitted generationally in the cell body of the germ cells, independent of the DNA."
The study also found that the progeny of the starved worms had a longer life span than the progeny of the controls. "We have not shown that the starvation-induced small RNAs were responsible for the increased longevity - it's just a correlation. But it's possible that these small RNAs provided a means for the worms to control the expression of relevant genes in later generations."
Link: http://www.eurekalert.org/pub_releases/2014-07/cumc-ssh071614.php