By: Chris O'Shea
Let's say, many years ago, your ancestor attempted the foolish endeavor of making a shark his pet. The shark, being a shark, bit your ancestor instead, completely severing his leg. Your ancestor didn't enjoy fish much after that. Could this incident, which had nothing to do with you, be responsible for your unexplainable fear of water? That's the question some scientists are trying to figure out, after learning that mice can inherit fears from previous generations.
The roots of the study began in an interesting place. Kerry Ressler, a neurobiologist and psychiatrist at Emory University first got the idea that memories and fears could be passed down through generations after working with poor people in Atlanta. He wondered why — and how — some poor people were unable to escape the cycle of poverty and drug addiction. From there, Ressler began to explore something called epigenetic inheritance. Epigenetics is the study of inheritable changes in gene activity that aren't the result of a change to the actual DNA sequence.
Together with a colleague — Brian Dias — Ressler used mice to see if there was anything to his theory. The duo trained a group of mice to fear the smell of Dias of acetophenone, a chemical that smells like a mixture of almonds and cherries. He and Dias sent acetophenone into the mice's cage, and when they smelled it, shocked them. Eventually, every time the mice smelled the chemical, they ran with fear and shuddered when it was sent in, even when there wasn't a shock. This, once again, proves that lab mice have the worst lives.
This reaction to acetophenone was seen in the mice's offspring and descendents. Mice born directly from the original two had never been shocked in the presence of the chemical's odor, but were scared when they smelled it. The third generation of mice exhibited the fear too. These findings are pretty crazy. Could DNA really be changed that easily? And so much so that fear is passed down through generations?
The uniqueness of Ressler and Dias' study have earned a collective side eye from the science community. "The overwhelming response has been 'Wow! But how the hell is it happening?" Dias is quoted exclaiming in Nature. Tim Bestor, a molecular scientist at Columbia University, had a harsher response, explaining in the same Nature article that "The claims they make are so extreme they kind of violate the principle that extraordinary claims require extraordinary proof."
Since this is the first study to show this finding, more experiments will need to be conducted before anything is proven. However, it's still fascinating. To think that what you do now could impact future generations' DNA is amazing. Maybe it's time to get over that fear of the water. For your grandkids' sake.
[Image via Flickr - Mark Fowler]