Stress-Response to a Smell Might be Triggered by Grand-Parents' or Parents' Olfactory Experiences {The 5th Sense in the News}
Cherry Blossoms in France ©The Scented Salamander
A study led by Brian Dias at Emory University School of Medicine in Atlanta has shown that a stress-response - fear in this case - might be transmitted trans-generationally and bear an epigenetic explanation. Mice that were conditioned to associate pain with the smell of cherry blossom (acetophenone) after a while started shaking even when no longer subjected to electric shocks. The revelation is that their descendants had inherited the fear reaction to the scent of cherry blossom even when not having experienced pain when smelling cherry blossom, nor having been in contact with their parents, and even when conceived in vitro...
The hypothesis is that somehow the information derived from this past experience had been transmitted via the sperm which carried the information. The sensitized parents gave birth to offspring who had more smell receptors called M71, the ones on which the smell of cherry blossom binds. They could detect it at lower threshholds.
While the findings are startling, they raise further higher the bar to prove them.
"Not everyone is convinced that smell memories can be inherited, however. For one thing, not all descendants of smell-conditioned mice were easier to startle than control mice – it is not yet known why. Neither have Dias and Ressler provided evidence that the epigenetic changes they found in the sperm were directly responsible for functional changes in the brain.
"The idea that something you smelled and became sensitive to can be transmitted across generations is astonishing, but I think it needs truly robust data to support it," says Isabelle Mansuy at the University of Zurich, Switzerland. "It's such an important question – one that touches fundamental concepts in genetics and epigenetics – so it's extremely important that the experimental design be rigorous and data be carefully interpreted."
