My comment on “Male Microchimerism in the Human Female Brain”

Recently I came across and interesting article  “We Are Multitudes.[2] which highlights evidence that DNA from children become a more or less permanent part of the mothers being.   Although this article does not mention the fathers DNA, the fact that the children have half of their DNA from their father, not only does DNA from the children become part f the mother but so does DNA from the father.   This is interesting considering the Biblical truth that husband and wife become one flesh.

The article is journalist, Katherine Rowland.[1] It appears to be well researched, and provides a lot of supporting scientific evidence.  Christians who read it may object as the article does have  an evolutionary bias but this does not negated the evidence that some of the DNA of children, carried in the mother’s womb, becomes part of the mother.

I thought it would be good to look at the quality of the scientific studies referred to in  Katherine’s  article.  Below is a start at this.

One of the references Katherine uses is titled,”Male Microchimerism in the Human Female Brain.”[3] It is a study which finds male DNA in the brain tissue of women.  Below are some of my thoughts.

In this study the authors tested brain tissue, which had been saved from  59 deceased women, and searched  for the presence, in these female brains, of a DNA sequence that is only found on the Y chromosome.  The Y chromosome is found only in male cells.

From stored brain tissue of the 59 female brains tested , 63 percent had evidence of Y chromosome DNA.  They used a test called PCR.  It has become a common test to look for particular stands of DNA in a variety of situations.  I think it is considered reliable.  But if some sample were somehow contaminated with cellular material from a man then the test could come up with a false positive.  The description of the detection method used in the study indicates they did set the process up to minimize contamination with male cellular material during the testing.  They suggest this means “the estimates of male DNA in the female brains might be lower than the true values.”

The theory is that the Y (male) chromosome DNA found in a woman’s brain came from a son she carried in her womb.  It would be great to be able to compare brains of women who had sons to those who had not. Unfortunately, of the source of brain tissue samples tested, “Limited pregnancy history was available.”

Of the limited available pregnancy data, 9 of the women whose brains were tested were known to have had a son.  Of the 9 known to have had sons 5 were positive for Male DNA.    Of course we do not know if the 5 positive had more sons than the 4 negative.  (Of these 9, no control group of those known to have not had sons was provided to compare to.)

In order to try to sort out the question about whether the male DNA came from sons, and to investigate the fact (they present this as fact, I have not looked into Alzheimer’s and number of pregnancies before) that women who have had children are at higher risk of Alzheimer’s than women who have no children, they compared the levels of male DNA in brains of women who died without Alzheimer’s to those who died with Alzheimer’s.  They found a lower level of male DNA in the brains of women with Alzheimer’s.  This is the opposite of what they expected to find.  They point out that “the number of subjects tested was modest and pregnancy histories were largely unknown.”  Given the small number of subject tested it is possible that the women who did not have a diagnosis of Alzheimer’s happened, in those studied, to have had more sons.  This is impossible to know.

This is an interesting study.  This study appears to be attempting to determine the truth (Thus is real science).  This study demonstrated Y-Chromosome DNA is found in a significant portion of women’s brains (at least of the ones studied).  The study does not prove the Male DNA came from having had sons.  Using a DNA sequence only found on Y chromosome means it is highly unlikely the Male DNA came from the women’s fathers.  When a women starts to grow in the womb she has no Y Chromosomes.  I believe it has been shown in the number of other studies that the cells of babies and mothers are interchanged with each other during pregnancy and that some of this interchanged cellular material lasts for years after the pregnancy is over.  The working theory that the Y chromosome DNA found in the brains of women comes from their sons is still likely to be true.  (They make no comment about the possibility of sperm entering a woman’s blood, and somehow entering some of her cells as a possible source)

If a number of the other references in the  “We are multitudes” article are of similar quality to this study, then the article increases in the likelihood of it being credible in it comments on the science of Male DNA in women.  (Of course, Biblically, the article is not credible in its evolutionary commentary.)

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[1] Katherine Rowland is a journalist. Her work has appeared in Nature, the Financial Times, the Independent, OnEarth and other publications. She is the publisher and director of Guernicamagazine, and lives in New York City.

[2] The link to “We are multitudes” is : https://aeon.co/essays/microchimerism-how-pregnancy-changes-the-mothers-very-dna

[3] The link to “Male Microchimerism in the Human Female Brain” is:    https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0045592

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