Scientists bust myth that our bodies have more bacteria than human cells
nature.com
nature.com
So depending on how you draw the line there are 39 trillion non-human nuclei in a human body, and only 5 trillion human nuclei. That brings our non-human:human genetic ratio right back to 10:1. Though that too is misleading given the amount of DNA in each of those nuclei. (human cells have significantly more DNA in their genome than bacterial cells)
These headlines are ridiculous.
Also, you could enlist the population of mitochondria to weigh against bacteria if you really wanted to.
More to the point about ridiculous headlines, the ratio of 10:1 is easily within the possibilities, given the uncertainty in both estimates.
"there are 39 trillion separate non-human genomes in a human body, and only 5 trillion human nuclei." And you'd be correct in pointing out that that sentence is also a little wonky.
Which is the best metric? Nuclei, cells, dividable cells, base pairs, non-redundant base pairs, protein-encoding base pairs, expressed human protein, mass, species, etc?
It's difficult to get the nomenclature exactly parallel between mammalian and bacterial cells, much less fungal or viral material. But that's also the point. It's tricky to compare, and shouting that one comparison is wrong is just kind of click-baity.
> “It is good that we all now have a better estimate to quote,” says Peer Bork, a bioinformatician at the European Molecular Biology Laboratory in Heidelberg, Germany, who works on the human and other complex microbiomes. “But I don’t think it will actually have any biological significance.”
[1] Such as: "In 2014, Judah Rosner from the National Institutes of Health drew attention to this “fake fact” in a letter to Microbe magazine. More recent estimates, he noted, put the total number of human cells at anywhere from 15 trillion to 724 trillion, and the number of gut microbes at anywhere between 30 trillion and 400 trillion. Which gives a ratio that can best be expressed as ¯\_(ツ)_/¯."
Even given a "wide uncertainty" their estimate is still on the side of the microbial cells. That hardly warrants a headline saying "scientists bust myth" as the "myth" was often just phrased as a "there are more" not as a specific ratio of 10:1.