Single-celled bacteria living in and on our bodies outnumber human cells by at least 3 to 1 — and perhaps as much as 10 to 1. The latest estimates from the American Academy of Microbiology put our bodies at 37 trillion human cells and our microbiomes — as those bugs are collectively called — at 100 trillion. Yes, that’s right, our skin and guts, mouths and noses, along with every other body surface, are home to 100,000,000,000,000 microscopic bugs. The typical human microbiome is said to represent about 1,000 different species, with wide variation from one person to the next in exactly which species. If it’s still hard to fathom just how big a single microbiome is, consider this: That same report says those microbes, each vanishingly small and seemingly weightless on its own, add up to something like 2.5 pounds.from Genome Magazine see article here
If these statistics have you reaching for the hand sanitizer, slow down. The vast majority of these bugs are no threat at all. Quite the opposite, in fact. Many of them are our best friends and allies in myriad surprising ways that scientists are only now beginning to sort out. And to think that with all of those antibiotics and disinfectants we’ve been waging an all-out war. We really haven’t known microbes (or ourselves, for that matter) at all.
“We’ve had this perception of microbes as germs, as pathogens, as disease-bearing organisms,” says Lita Proctor, a scientist at the National Human Genome Research Institute and program director of the Human Microbiome Project. “Much of the scientific literature for decades and decades has been completely focused on pathogens, and that has also framed our point of view about microbes. But it has become clear that the vast majority of microbes we come in contact with on a daily basis are not pathogenic. They are either benign and couldn’t care less that there is a human nearby or they actually provide a benefit.”
Bacteria play essential roles in the development of our immune systems as newborn babies are colonized at birth and subsequently by microbes from mom and the environment. Once established, those microbes, and particularly those that fit our cells like a lock and key, provide us with energy sources and vitamins humans can’t make on their own. They produce ingredients that act as anti-inflammatories and send signals to our brain. “Good” microbes help us fend off the “bad” ones. We really can’t live without them.
The Other Human Genome
“Instead of declaring war, we need to think in the context of ecosystems that make up our bodies. Figuring out how to encourage good microbes while eliminating the bad will be of increasing importance.”
Despite their importance and value, all of these microbes had gone mostly unrecognized, especially in the biomedical field. That began to change substantially in 2007 when the National Institutes of Health launched the Human Microbiome Project, an effort to catalog the microorganisms living in and on healthy human bodies. It was in some ways a follow-up to the Human Genome Project. Scientists would apply rapidly improving DNA sequencing technologies to define what some like to consider the “other human genome” — the human microbiome — via samples taken from hundreds of healthy people and many parts of their bodies: behind the ear, the inner elbow, t