With the trillions and trillions bytes of data the Human Microbiome Project has generated, you can bet that findings aren't hard to come by. One of the first -- and more shocking -- discoveries was that based on the genetic content of the samples, there might be nearly 8 million unique microbial genes across the body of the adults studied. That's hundreds of times more than the human genome contributes to the body [source: Yang]. They also found that even these healthy people had microbes that could cause issues in a weakened immune system, but seemed happy to hang out harmlessly in most cases. That means that bacteria like staph and E. coli are present in normal people, but don't necessarily present an infection.
Even cooler: No one microbe was present in every person, which also seems to imply that there's no "normal" microbiome. They also found that microbes were most similar on the same site of different subjects. (Meaning that between two people, the microbial communities on the skin, for instance, were more alike than the microbial communities in different sites on one person.) But different bacteria may be performing the same function across different individuals: While two people can digest carbohydrates equally well, it might be two different species of bacteria that are doing the job in each person [source: Baylor College of Medicine].
Studying the human microbiome (and using the project's data) has already led to some fascinating results. A 2012 study found that the vaginal microbiome changes significantly with pregnancy. Lactobacillus johnsonii is a species of bacteria normally found in the gut to help digest milk, but it flourishes in the vagina when a woman is expecting. Scientists hypothesize that a baby coming through the vaginal canal -- and meeting microbes for the very first time -- might use those microbes to assist in digesting breast milk from the get-go [source: Zimmer]. There's also been some hypothesizing that a vaginal birth, which exposes baby immediately to intestinal, vaginal and skin microbes, might prove to be more ideal to the immune system of a baby than a sterile cesarean section birth. A study in Puerto Rico is studying whether swabbing C-section babies with vaginal secretions soon after birth might contribute to a hardy bacterial colony [source: Gitig].
And let's not forget that studying bacteria will hopefully lead to a better understanding of antibiotics and bacterial resistance. No longer is it viable to assume that "good" bacteria will automatically repopulate after the "slash and burn" that takes place when an antibiotic is introduced. Scientists are thinking about microbial environments that need careful pruning and fostering. Instead of giving antibiotics to kill staph, an alternative might be apply a cream that good bacteria can feed on to help overthrow the staph intruders [source: Zimmer].
To learn a lot more about the microbial friends that hang out rent-free on your person, check out the next page for lots more information.