In the experiment, researchers taught male mice to fear the smell of cherry blossoms by associating the scent with mild foot shocks. Two weeks later, they bred with females. The resulting pups were raised to adulthood having never been exposed to the smell.
Yet when the critters caught a whiff of it for the first time, they suddenly became anxious and fearful. They were even born with more cherry-blossom-detecting neurons in their noses and more brain space devoted to cherry-blossom-smelling.
The memory transmission extended out another generation when these male mice bred, and similar results were found.
Neuroscientists at Emory University found that genetic markers, thought to be wiped clean before birth, were used to transmit a single traumatic experience across generations, leaving behind traces in the behavior and anatomy of future pups.
Epigenetics studies how molecules act as DNA markers that influence how the genome is read. We pick up these epigenetic markers during our lives and in various locations on our body as we develop and interact with our environment.
The findings were also verified by comparing the epigenetic markers on the DNA of sperm, specifically on the gene responsible for detecting cherry blossoms. On the sperm of the cherry-blossom-fearing mice, there was less of the methylation that can silence genes, possibly pointing to a mechanism of how the information got passed down.
Studies on humans suggest that children and grandchildren may have felt the epigenetic impact of such traumatic events such as famine, the Holocaust and the Sept. 11, 2001, terrorist attacks.