If you’ve spent virtually any time on the interwebs, and particularly lurked in the social media areas of this marvel of human ingenuity, you’ll no doubt at one point or another come across the fact that many women have living male cells hanging out in their bodies, including in their brains.
The most common explanation, according to social media, for how these instances of microchimerism came to be is that women acquire these cells via making the beast with two backs with a man. The claim that often follows this is that, given these cells and their replicates have been shown to sometimes hang around for decades in the women, that most women have the DNA of every male sexual partner they’ve ever had in their bodies.
But is any of this actually true?
As with the vast majority of “quick facts” spread around on social media, there are elements of truth to it, but the part that makes the fact spread does not appear to be true at all based on the current state of scientific research. Unlike the effect of having unprotected social media, which will always leave residual undesired things in your brain, having sex with a guy doesn’t seem to be a contributor, or at least not a major contributor, to male cell lines finding their way into women’s bodies and brains. So how do these cells get there and where did the rumor that women retain the DNA of every man they ever slept with start?
To begin with, back in 2012 a study titled, Male Microchimerism, noted that after dissecting a number of deceased women’s brains, 63% of the brains (37 out of 59) had male microchimerism present. While it was touted by many a media source that this was a huge discovery, in fact, it has long been known that a large percentage of women eventually carry living male cell lines in their bodies. For example, a study in 1969, published in The Lancet, showed that 70% (21 of 30) pregnant women, 19 of whom were pregnant with boys and 2 others having previously had boys, were found to have male microchimerism.
From there countless other studies have shown the same thing, including some animal studies that showed some of these cell lines are able to cross the blood-brain barrier in mice. What made this particular 2012 study interesting was simply that it was the first to show these cell lines could cross the blood-brain barrier in humans too.
It’s also interesting to note from this study that 33 of the women had Alzheimer’s and that these women had lower likelihood of having male microchimerism present. And even those who had Alzheimer’s AND male microchimerism, they tended to have lower concentrations of these cells. More on this and the potential benefits and drawbacks of this microchimerism in the Bonus Facts in a bit.
In any event, noteworthy here is that despite explicitly stating the likely sources of these cell lines- mostly centered around pregnancy- at no point in the study did the researchers state that these came from former sex partners. And as for the pregnancy source, the researchers speculate this may be how the cell lines are getting past the blood-brain barrier in the first place. As they state, “Changes in BBB permeability occur during pregnancy and may therefore provide a unique opportunity for the establishment of [microchimerism] in the brain.”
The most common explanation, according to social media, for how these instances of microchimerism came to be is that women acquire these cells via making the beast with two backs with a man. The claim that often follows this is that, given these cells and their replicates have been shown to sometimes hang around for decades in the women, that most women have the DNA of every male sexual partner they’ve ever had in their bodies.
But is any of this actually true?
As with the vast majority of “quick facts” spread around on social media, there are elements of truth to it, but the part that makes the fact spread does not appear to be true at all based on the current state of scientific research. Unlike the effect of having unprotected social media, which will always leave residual undesired things in your brain, having sex with a guy doesn’t seem to be a contributor, or at least not a major contributor, to male cell lines finding their way into women’s bodies and brains. So how do these cells get there and where did the rumor that women retain the DNA of every man they ever slept with start?
To begin with, back in 2012 a study titled, Male Microchimerism, noted that after dissecting a number of deceased women’s brains, 63% of the brains (37 out of 59) had male microchimerism present. While it was touted by many a media source that this was a huge discovery, in fact, it has long been known that a large percentage of women eventually carry living male cell lines in their bodies. For example, a study in 1969, published in The Lancet, showed that 70% (21 of 30) pregnant women, 19 of whom were pregnant with boys and 2 others having previously had boys, were found to have male microchimerism.
From there countless other studies have shown the same thing, including some animal studies that showed some of these cell lines are able to cross the blood-brain barrier in mice. What made this particular 2012 study interesting was simply that it was the first to show these cell lines could cross the blood-brain barrier in humans too.
It’s also interesting to note from this study that 33 of the women had Alzheimer’s and that these women had lower likelihood of having male microchimerism present. And even those who had Alzheimer’s AND male microchimerism, they tended to have lower concentrations of these cells. More on this and the potential benefits and drawbacks of this microchimerism in the Bonus Facts in a bit.
In any event, noteworthy here is that despite explicitly stating the likely sources of these cell lines- mostly centered around pregnancy- at no point in the study did the researchers state that these came from former sex partners. And as for the pregnancy source, the researchers speculate this may be how the cell lines are getting past the blood-brain barrier in the first place. As they state, “Changes in BBB permeability occur during pregnancy and may therefore provide a unique opportunity for the establishment of [microchimerism] in the brain.”
