Racial Memory By Brian Simpson

Here is more evidence of the existence of a type of racial memory; fear of a smell can be passed down the generations. So, what else can be, like fear of enemies? I hope so, that’s what we need now.

https://www.newscientist.com/article/dn24677-fear-of-a-smell-can-be-passed-down-several-generations/

“If a particular smell makes you uneasy but you don’t know why, perhaps you should ask your grandparents.

Mice whose father or grandfather learned to associate the smell of cherry blossom with an electric shock became more jumpy in the presence of the same odour, and responded to lower concentrations of it than normal mice.

This work, led by Brian Dias at Emory University School of Medicine in Atlanta, provides some of the best evidence yet for the inheritance of memories or traits across generations. It also sheds fresh light on the biological mechanism by which such traits might be passed down generations.

Previous studies have hinted that stressful events can affect the emotional behaviour or metabolism of future generations, possibly through chemical changes to the DNA that can turn genes off and on – a mechanism known as epigenetic inheritance.

Needle in a haystack

However, although epigenetic changes have been observed, identifying which ones are relevant is a bit like searching for a needle in a haystack. That’s because many genes control behaviours or metabolic diseases like obesity.

Smell is a little different though. Individual odours, such as acetophenone (which smells like cherry blossom) often bind to specific receptors on the olfactory bulb, the interface between the nose and brain – in this case to a smell receptor called M71. “Since we know the gene encoding this receptor, we can look at it and the haystack becomes a little smaller,” says Dias.

Male mice have previously been conditioned to associate the smell of acetophenone with an electric shock and became fearful of it as a result. They also developed more M71 receptors, which enabled them to detect acetophenone at much lower levels.

Dias and Kerry Ressler, also at Emory, took sperm from these conditioned mice and used it to inseminate female mice. When the offspring from these pairings were exposed to acetophenone they were more jumpy than when they smelled a neutral odour – even though they had never smelled acetophenone before. The same was true of their grandpups. When the pups were exposed to a different smell, they showed no enhanced response.

Brain change

The offspring also had more M71 receptors in their brains than did mice born from parents who had not had the smell conditioning and were more sensitive to it. “There was more real estate devoted to this particular odorant receptor, suggesting that there’s something in the sperm that is informing or allowing that information to be inherited,” Dias says.

DNA sequencing of sperm from the grandfather mice and their sons also revealed epigenetic marks on the gene encoding M71 that weren’t seen in control mice.

Female mice conditioned to fear acetophenone also appeared to transmit this “memory” to the next generation, although epigenetic marks on their eggs have not yet been analysed.

Moshe Szyf at McGill University in Montreal, Canada, describes the results as unprecedented and startling. “It suggests that there is a very particular, specific and organised transgenerational transfer of information,” he says.

Marcus Pembrey at the University of Bristol, UK agrees. “It is high time public-health researchers took human transgenerational responses seriously,” he says. “I suspect we will not understand the rise in neuropsychiatric disorders or obesity, diabetes and metabolic disruptions generally, without taking a multigenerational approach.”

Permanent changes?

The mystery remains as to how a bad memory could get transmitted to the sperm and prompt chemical changes to the DNA, or how these chemical changes could be translated into a behavioural change in offspring.”

That of course, is yet another research problem for conventional biology, which has hand waving stories involving microRNA, and hormones. The difficulty is how the fear response gets encode, and the mechanism for doing this.