A new study suggests there is a genetic imprint from traumatic experiences carries through at least two generations. I saw this and was IMMEDIATELY skeptical. Too much remains unanswered and also goes against what we already know.
Certain fears can be inherited through the generations, a provocative study of mice reports1. The authors suggest that a similar phenomenon could influence anxiety and addiction in humans. But some researchers are sceptical of the findings because a biological mechanism that explains the phenomenon has not been identified.
Ressler and his colleague Brian Dias opted to study epigenetic inheritance in laboratory mice trained to fear the smell of acetophenone, a chemical the scent of which has been compared to those of cherries and almonds. He and Dias wafted the scent around a small chamber, while giving small electric shocks to male mice. The animals eventually learned to associate the scent with pain, shuddering in the presence of acetophenone even without a shock.
This reaction was passed on to their pups, Dias and Ressler report today in Nature Neuroscience1. Despite never having encountered acetophenone in their lives, the offspring exhibited increased sensitivity when introduced to its smell, shuddering more markedly in its presence compared with the descendants of mice that had been conditioned to be startled by a different smell or that had gone through no such conditioning. A third generation of mice — the ‘grandchildren’ — also inherited this reaction, as did mice conceived through in vitro fertilization with sperm from males sensitized to acetophenone. Similar experiments showed that the response can also be transmitted down from the mother.
The findings are contentious. While the proposal is astounding – one observer called it “the most rigorous and convincing set of studies published to date demonstrating acquired transgenerational epigenetic effects in a laboratory model” – the rest of the community is stumped by the lack of a mechanism for this “memory” to be transmitted. This is important because without a plausible mechanism, some other factor could account for the results. Science is conservative. Skepticism (which is of critical importance in scientific discussions) will continue until the molecular mechanisms can be detailed and that could be a while.
So, file this research as something to watch, not swallow whole right of the bat. This is an extraordinary claim and extraordinary evidence is not there yet.
Here is the paper link: Parental olfactory experience influences behavior and neural structure in subsequent generations : Nature Neuroscience : Nature Publishing Group.[Full view by subscription only]