.

A lot of us already have heard that people are outnumbered by other creatures and that’s not even counting things that don’t live under our own skins. Ten times more individual microbes occupy the average person’s digestive tract than that person has individual human cells in his or her own body.

But now the census has gotten beyond counting heads and done some demography. A report in Nature has it that, after analysis of  different species of bacteria and other microflora in the human gut, that they should in aggregate be considered a second human genome. Every person, it appears, has around 160 different species. Everyone does not have the same ones, but there is a good deal of overlap.

Stories:

• Not Exactly Rocket Science – Ed Yong (blog) : The bacterial zoo in your bowel ; Not only a skillfully done piece from this Brit science writer, if only a blog, but source for this post’s illus.
• AP – Seth Borenstein: Scientists catalog zoo of bacteria inside our guts ; Short and to the point, but includes quotes gotten directly from one author, and an opinion for an outside expert. A usage question: what is the difference between gut and guts? And why use both?
• Independent (UK) Steve Connor: Revealed: the 160 species living inside our guts ; Clever lead: “Some scientists dream of sending a probe to Mars, others….” etc. It includes an estimate of how many different species, total, are found at home in one person or another. More than 1,000. It also says the human colon has the highest bacterial density of any known ecosystem. Yuck. Somebody check manatees, or sloths, or possums, or bats. Surely something has us beat.
• BBC – Doreen Walton: Human gut microbes hold ‘second genome’ ; Another piece long enough to tell people more than merely what a bunch of fellow travelers we carry about. It puts irritable bowel syndrome in a new light.
• Reuters – Tan Ee Lyn: Links seen between gut bcteria and disease: paper ; Filed from Shenshen, China. Based on a phone interview with a lead author – with the result a perhaps excessive focus on just a few diseases whose causes might be better illuminated now. It seems to go too directly to the work’s applications without first easing people through the basics, such as just how crowded thing are in one’s stomach and beyond.

One wonders, idly. Given the somewhat common obsessive-compulsive disorder and phobia about germs, leading in some cases to constant hand-washing and other distractions (Howard Hughes, for one example, and a certain game show host who cannot easily bring himself to shake hands with anybody), does learning that we are naturally, necessarilly,  and inescapably bursting with germs make the psychological disorder fade,  or get worse?

One has other questions, such as how many if any of these microbes are unique to humans, how many are also common in the guts of other mammals or vertebrates and even worms for that matter, and so on. I know I’m carrying some E.coli and our cat probably is too. But what else?

Grist for the Mill: European Molecular Biology Laboratory Press Release ;

- Charlie Petit

This entry was posted on Thursday, March 4th, 2010 at 2:22 pm and is filed under Health & Medicine Stories, Science Stories. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.