Here’s something odd and fascinating and kind of beautiful that dramatically shifts our understanding of DNA and genetics.
Researchers have discovered that evidently, a lot of us harbor not only the unique mix of DNA we inherited from our parents, but also DNA we’ve picked up from other people along the way, proving on a genetic level that John Donne was SO right when he said that no man is an island. Scientists are calling these people chimeras, a term borrowed from a mythological creature which was made up from several different animals.
According to the New York Times article DNA Double Take, scientists have found cases where people who’ve received bone marrow transplants carry both their own DNA and the DNA of their donor, twins sometimes carry multiple genomes in their blood from fetal blood transfers, and a majority of mothers likely carry some DNA from the children they nourished inside their wombs while they were pregnant.
What I found particularly moving about the last example was this line from the article:
“Chimeric cells from fetuses appear to seek out damaged tissue and help heal it, for example.”
Evidently, pregnant women have been benefitting from a natural form of fetal stem cell transplant for aeons. Now that’s a loving exchange on the most visceral level.
In addition to sharing our DNA among us, it’s also not uncommon for any one of us to carry alternate DNA resulting from genetic mutations in various parts of our bodies…in other words many of us have multiple genomes inside us that we made up all by ourselves. We’ve known for a long time that that’s how cancers tend to get started, but evidently other non-cancerous cells can do the same thing, sometimes for better and sometimes for worse:
“Now that scientists are beginning to appreciate how common chimerism and mosaicism are, they’re investigating the effects of these conditions on our health. “That’s still open really, because these are still early days,” Dr. Urban said.
Nevertheless, said Dr. Walsh, “it’s safe to say that a large proportion of those mutations will be benign.” Recent studies on chimeras suggest that these extra genomes can even be beneficial….
…But scientists are also starting to find cases in which mutations in specific cells help give rise to diseases other than cancer.”
Needless to say this is to some extent changing the way that we’ll have to approach everything from genomic medical research and diagnoses to forensic science (a cheek swab might deliver two sets of DNA for instance) as well as the growing field of genetic counseling. It looks like human beings are not going to be quite as easy to map and label as we once thought.
And I admit, I just love that.
‘No Man is an Island’
No man is an island entire of itself; every man is a piece of the continent, a part of the main; if a clod be washed away by the sea, Europe is the less, as well as if a promontory were, as well as any manner of thy friends or of thine own were; any man's death diminishes me, because I am involved in mankind. And therefore never send to know for whom the bell tolls; it tolls for thee.
(For any other lit geeks like me out there, you can find the above version of John Donne’s poem as well as the olde english version here.)
copyright Dia Osborn 2013