Wednesday, September 23, 2009

to the seventh generation

There was an interesting program on genetics on Nova last night.  When they started the human genome project, to map the DNA of human beings, the scientists thought we would have the most genes of any living creature.  Turns out we’re not that complex.  We don’t even have as many genes as some plants.  Scientists also thought that once they had the genetic code, that the mystery would be revealed.  Turns out we’re not that simple.  Why was it that two people who share the exact same genetic code, as identical twins do, can develop so differently.  Why one is normal and the other is autistic, why is one healthy and the other gets a terrible disease, why is one happy and productive and the other suffers from debilitating depression?

They have discovered now that some of our individual DNA, collectively our genome, come with chemical markers, the epigenome.  These markers turn genes off and on so that even in identical twins who have the exact same genome, their markers can be different.  And they accumulate as a person ages, or rather, the effect of these markers accumulates through aging causing greater and greater differences.  We all have them but they became apparent in the study of identical twins.

These epigenomes are inherited of course, but they are also environmentally created and attach themselves to the genome.  For instance, exposure to chemicals, pesticides and insecticides.  Didn’t we all, as children in the 50s, run through the clouds of insecticide that the city sprayed at night, because we were told it was harmless to humans?  Harmless to us perhaps but certainly not to our descendants.  

Other environmental factors come into play as well like feast or famine.  It was determined in one study that if your grandfather suffered through famine when he was about 10 years old it had a beneficial effect on the lifespan of his grandchildren.  If he had plenty during that age then his grandchildren were more likely to develop a life threatening disease and lived for a shorter time.  Similarly, if your grandmother suffered feast or famine while she was still in the womb, it had an effect on the health and life span of her grandchildren.

Our food supply became more and more adulterated in the 50s and 60s with the addition of chemicals, colors, preservatives and refining and it correlated with the rise of cancer, diabetes and allergies.  Our parents didn’t suffer nor did we of my generation for the most part but now look 3 and 4 generations later with the accumulation of these chemical markers on our genome, these ailments are rampant.

The hope, of course, is that we can use this new knowledge to mitigate some of the effects of the pollution of our environment and food supply on our genome but in the meantime, maybe that old biblical curse isn’t so far-fetched after all.


  1. Sorry I missed that episode of Nova...I would have loved it. My sister and I sent our DNA off to be tested this summer. It was interesting to compare the genome markers. In a sets of pairs, we had at least one matching number.

  2. Ellen, this is so interesting. And scary. But such information shows us our work is cut out for us. We must set the healing process in motion for our children's children's children.

  3. I find the study of genetics fascinating, although I lack the biochemistry background to understand the real details of it.

    I believe it is only a matter of time before scientists discover how to deactivate the specific gene sequences that cause cancer, Parkinson's Disease, and countless other genetically inherited disorders. I further believe it is only a matter of time before humans will be able to grow new organs and limbs to replace damaged or diseased ones. We are witnessing the very beginnings of the next revolution in medicine here.

    Of course that also comes with a down side - as always, there is great potential for the misuse of this technology.

  4. I missed the episode. Very interesting.

  5. hello ellen - i said to my class this very morning - "how many of you have allergies?" most hands went up. "how many of you have puffers?" one third of my class. i told them truly - i knew no one with allergies, no one with puffers when i was your age. so i asked them what has changed?
    you know what ellen? they know.


  6. Fascinating stuff! Very intelligent and provocative AND frightening. For a minute, I felt completely relieved and blessed that my son and daughter come from a family of healthy longevity and were not born with any catastrophic or debilitating health issues. Then I realized, maybe their children might.

  7. The human body amazes me ... Great post!

  8. Interesting informatoin...and frightening. But I prefer to stay advised so thanks for sharing.

  9. This sounds quite fascinating and frightening... and rather complex after al. Hopefully that episode will repeat sometimes, or perhaps it can be found online. Thanks for sharing the info.

  10. I've always known about my cast-iron stomach. Never a cold sore either. Scary post.


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