Along with eye color, height and dimples, parents’ fears can pass down to children, scientists report December 1 in Nature Neuroscience. The results, from experiments with mice, suggest how fallout from a person’s traumatic experiences might ripple through generations.
Mouse parents learned to associate the scent of orange blossoms with a shock. Their children and their grandchildren startled in response to the scent — a sign of fear — even though they had never smelled it before. Offspring also had more neurons that detect the orange blossom scent than mice whose parents weren’t exposed to the scent.
Sperm cells alone can deliver this fear message, study authors Brian Dias and Kerry Ressler of Emory University found. DNA in the sperm cells was imprinted with this fearful association: A gene that codes for the molecule that detects the orange blossom odor carried a chemical stamp that may have changed its behavior.
Information from parents’ experiences could be important for survival. Knowing that a particular scent signals a nasty shock could help an animal avoid trouble without having to endure the shock firsthand. Ancestral experience could be an underappreciated influence on animals’ and people’s brains and behaviors, the authors write.