Mice biologically inherit information learned by their grandfathers reports a paper published online this week in Nature Neuroscience. This research provides evidence that subsequent generations can benefit from the specific experiences of their ancestors through the transmission of modified DNA.
Genes can be turned on or off in a semi-permanent manner with molecular changes to the DNA, known as epigenetic marks, and some of these changes can be maintained across generations. Traumatic or stressful experiences in animals typically have been associated with effects on the emotional behavior of later generation offspring through epigenetic changes.
Brian Dias and Kerry Ressler show, however, that specific learned information can be transmitted to subsequent generations through reproductive cells. The authors trained mice to fear a cherry blossom-like smell and then allowed these mice to mate and conceive offspring. These offspring exhibited more fearful responses to whiffs of cherry blossom than to a neutral odor despite never having encountered these odors before. Moreover, the next generation of offspring showed the same behavior. This fear response was transmitted to offspring even if they were conceived with artificial insemination using sperm from cherry blossom fearing fathers. The team also found that both in the trained mice and their offspring, the fear response was associated with structural changes to the brain, specifically to regions used to detect the feared odor, and with epigenetic marks in the sperm on the gene responsible for detecting the odor.
Future studies are needed to determine how experiences stored in the brain circuits are transferred and stably encoded into the genome for future generations.