Friday, January 15, 2016

Your cells outnumber bacteria

It is always interesting to see some widely-cited textbook fact proven false.

Nature mag reports:
It's often said that the bacteria and other microbes in our body outnumber our own cells by about ten to one. That's a myth that should be forgotten, say researchers in Israel and Canada. The ratio between resident microbes and human cells is more likely to be one-to-one, they calculate.

A 'reference man' (one who is 70 kilograms, 20–30 years old and 1.7 metres tall) contains on average about 30 trillion human cells and 39 trillion bacteria, say Ron Milo and Ron Sender at the Weizmann Institute of Science in Rehovot, Israel, and Shai Fuchs at the Hospital for Sick Children in Toronto, Canada.

Those numbers are approximate — another person might have half as many or twice as many bacteria, for example — but far from the 10:1 ratio commonly assumed.

“The numbers are similar enough that each defecation event may flip the ratio to favour human cells over bacteria,” they delicately conclude in a manuscript posted to the preprint server bioRxiv.
So a trip to the toilet can let you outnumber the bacteria.

There are lots of other examples. Astronomers used to say that Saturn's rings were only a few million years old, but now they say billions. They used to say that Earth's water came from comets, but now isotopic evidence has caused that to be doubted.

On another matter, the Wash. Post has now admitted that the Univ. of Virginia Rolling Stone fraternity rape story was a catfishing hoax by a girl trying to make a boy jealous. This is about a year after blogger Steve Sailer said that it was obvious.

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