Stress ‘memories’ can be passed down from generation to generation by being passed from cell to cell, and therefore from mother to daughter, according to research.
It follows a study in mice which showed that frightening memories of a smell could be passed from parent to child without the child ever smelling the smell.
The process, known as “epigenetics,” does not mean that the genes themselves are changed by, say, stressful events; rather that there are changes in how these genes are packaged and expressed.
The study, published in the prestigious journal, Scienceprovides evidence for a controversial theory that “memories” can be passed down through the genetic code (Gaydos et al., 2014).
Many scientists are skeptical of studying epigenetics because the mechanism is unproven.
Nevertheless, there is some evidence that “memories” of early life stress can be transmitted epigenetically from parents to children, leading to a higher rate of adult depression in their offspring (Caspi et al., 2003).
Addiction and depression can also be transmitted through epigenetic mechanisms (Short et al., 2016; Vassoler & Sadri-Vakili, 2014)
The study takes advantage of a chemical change called “methylation” that occurs in a particular protein called histone H3, which has been well studied in epigenetics.
The same protein is found in all multicellular animals, from humans to the worms that were used in this study.
Professor Susan Strome, a biologist at the University of California, Santa Cruz who led the study, said:
“There has been an ongoing debate about whether the methylation mark can be passed through cell divisions and from one generation to the next, and we have now shown that it is.”
In their research, Professor Strome and his colleagues bred worms that had the gene knocked out, which creates the methylation mark.
These were then bred with normal worms.
By following the chromosomes of normal and mutated worms as they divide and grow, the researchers were able to show the critical mark of methylation moving from one generation to the next.
Professor Strome concluded:
“Transgenerational epigenetic inheritance is not a settled field – it is very much in flux.
There are dozens of potential epigenetic markers.
In studies that document parent-child epigenetic inheritance, it is unclear what is passed on, and understanding it molecularly is very complicated.
We have a specific example of epigenetic memory being passed on, and we can see it under the microscope.
It’s a piece of the puzzle.