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New Life For The Ghost In Your Genes

Is DNA destiny? NOVA's Ghost In Your Genes, which will be rebroadcast this Tuesday on many PBS stations (check local listings), provides fresh hope that our fate isn't inscribed in our genes. A "second genome," or epigenome, which has only recently caught scientists' attention, can switch genes on and off with chemical tags. And though you can't rewrite your genes, you just might be able to change your epigenome.

How? Diet and exposure to toxins, like those in cigarettes, probably play a role. But Moshe Szyf and Michael Meaney, scientists at McGill University in Montreal, wanted to find out if a person's upbringing could influence his epigenome. Would abuse, neglect, and stress leave an imprint? Meaney and Szyf thought so, and set out to test their hypothesis on rat pups.

One group of pups was coddled. Their mothers licked and groomed them and sang them sweet rat lullabies every night. (Okay, maybe not that last part.) The second group of rats, assigned to "low licking" mothers, didn't get the same love.

Sure enough, when the pups matured, they behaved differently: Blood pressure and stress hormones shot up higher in the neglected pups than in the nurtured ones when both groups were put in stressful situations. Meaney and Szyf found out why when they looked at a gene, active in a part of the rat's brain called the hippocampus, which tamps down the level of stress hormones in the blood. In the rats that grew up with lots of TLC, this gene was going strong. But in the neglected rats, multiple epigenetic tags were silencing it.

Not convinced yet? There's more: Szyf and Meaney injected the neglected rats with a drug designed to erase the epigenetic marks, switching the silenced gene back on. Suddenly, the nervous-Nellie rats were transformed into placid, low-stress critters, indistinguishable from the nurtured rats.

This is the part in Ghost In Your Genes where the narrator rumbles in with a caveat: "Could this have implications for humans? We will not know until the completion of a 10-year study, now underway, that will look at children from both nurturing and neglected backgrounds." Though that study in not yet complete, in the three years since the film's 2007 premiere, the science has advanced significantly: Szyf, Meaney, and their colleagues have found analogous epigenetic changes in the brains of humans who were abused as kids.

It's not news that childhood abuse is often linked to psychiatric disorders down the line. But, as Szyf explains, epigenetics provides "a molecular explanation" for the social and psychological context that connects abuse with behavioral challenges later in life. "Epigenetics creates a meeting ground between biology and the social sciences," says Szyf. Many molecular biologists have derided the social sciences "soft" in the past. Szyf hopes that this discovery "will bring these sciences back the prestige they deserve."

After all, says Szyf, "People are not just molecules." But molecules might reveal exactly how experience interacts with biochemistry to make us who we are.

User Comments:

Very interesting information. I love Nova always exciting to watch and new discoveries,
Please keep it coming....


Thirty years ago, I was part of a discussion on various topics when someone brough up the subjects of "Deja Vu" and reincarnation.

I have never believed in either.

As for reincarnation, the simple reason would be, if a person died, over and over and kept returning, the population of the earth would never have increased.


As for "Deja Vu" - I believe if we have some sort of strange memories, it is because we have inherited those memories from an ancestor who did experience such things and it is just a genetic memory for us.

We have received the genetic memory cells from our ancestors and that is why we 'think' we have 'been there before' or have experienced the same things and yet have never been to a particular place or area.

What about the children that have not been treated "nicely' by their mothers but have not been abused a lot, say, beaten up every day, but nevertheless have been nurturing to thier own children and also have excelled in academocs and in many other segments of life. ?

The epigenome concept is an from an environmental standpoint should be of great concern when we continue to allow more and more toxic chemicals into the environment without first stepping back and taking a second look at how these compounds may effect not only our life, but the lives of future generations. Flawed public health policies like water fluoridation where over 170,000,000 people in the United States are exposed to this toxic waste on a daily bases is just one example of how these man made chemicals are effecting our epigenome and the inhertience of our future generations to disease from these exposures.

Very interesting web site. One day, maybe everyone on the web with any brains or talent or

even without it will stumble on what we really are-us humans-AFTER they read "On Human

Nature" by E. O. Wilson. We can all learn from some serious thinking-before we eliminate

ourselves -or nature does it for us.

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