Learned experiences can be transferred through genetic structures—not by changes to genes themselves, but rather, to how they are “marked” by other molecules, a study reports.
Such “markings” are called epigenetic changes. Scientists in recent years have increasingly recognized them as playing important roles in biological inheritance.
The finding that learned experiences may be transferred this way is part of a recent wave of research overturning what biologists used to assume—that only information in the DNA itself is passed across generations.
The study, published online Dec. 1 in the research journal Nature Neuroscience, argues that mice biologically inherit information learned by their grandfathers.
Genes can be turned on or off semi-permanently with molecular changes to the DNA, known as epigenetic marks. Some of these changes are maintained across generations, others aren’t. Through, epigenetic changes, past studies have linked traumatic or stressful experiences in animals to effects on later generations’ emotional behaviours.
In the new work, Brian Dias and Kerry Ressler of the Emory University School of Medicine in Atlanta, Ga. found that specific learned information can also be transmitted through epigenetic changes in sperm.
The researchers trained mice to fear a cherry blossom-like smell and then let these mice mate and conceive offspring. These offspring showed more fearful responses to whiffs of cherry blossom than to a neutral scent despite never having encountered the smells before, the scientists said.
Moreover, they added, the next generation of offspring showed the same behaviour. This fear response was passed to offspring even if they were conceived with artificial insemination using sperm, according to the researchers.
They also found that both in the trained mice and their offspring, the fear response was associated with changes to brain regions used to detect the feared scent, and with epigenetic marks in the sperm on the gene responsible for detecting the smell.