Stumbling along the cybernet, I came across this intriguing article about the extinction of our intestinal flora. The tag line here is:
Having evolved along with the human species, most of the miniscule beasties that live in and on us are actually helping to keep us healthy, just as our well-being promotes theirs. In fact, some researchers think of our bodies as superorganisms, rather than one organism teeming with hordes of subordinate invertebrates.
The human body has some 10 trillion human cells—but 10 times that number of microbial cells. So what happens when such an important part of our bodies goes missing?
It’s hard to appreciate just how symbiotic our relationship is. In fact, the flora has a collective metabolic activity equal to a virtual organ within an organ. Our body is well attuned to this fact: immunosensory cells can actually distinguish pathogenic bacteria from the helpful ones. So what are the functions of this virtual organ?
Well, they actually help us to break down some undigested carbohydrates; rodents raised in a sterile environment without gut flora need to eat 30% more calories. They are also able to repress pathogenic bacteria from colonizing the gut through a “barrier” effect. They help prevent allergies. They’re even able to help prevent cancers.
It’s interesting that we’ve been able to selectively allow bacteria to colonize our bodies – and it’s not just us mammals; certain ants have gut flora that allow them to obtain nutrition from honeydew. In fact, the reason that ants are able to be herbivores at all is due to their intestinal flora. Completely unrelated herbivorous ants have bacteria from the same order – as Myrmecos puts it, “The bacteria are not mere evolutionary hitchhikers passively tracking the genealogy. They show up in a highly non-random fashion in ants that have need of nitrogen.” But it gets even more interesting! Leafcutter ants not only employ antibiotics in their fungus gardens, they use colonies of the bacteria Klebsiella to capture atmospheric nitrogen and make it available to the fungus and the ants. I wonder how similar the evolutionary symbiosis of these bacteria is?
And now, here are a few of our friendly flora.