Dr. Bonnie Bassler of Princeton University describes an amazing bacterial "social life." Yes, they actually communicate in rather intricate ways. --That's the primary thrust of the following video. But she says something else, about a minute into the video, that ought to catch your attention, I think. Paraphrased: The human body has about a trillion cells in it. And those trillion cells host--either in you or on you--about 10 trillion bacteria. You have about 30,000 genes in you; the bacteria you host have about 100 times the amount of genetic material or information. "So," says Bassler, "when I look at you, I think of you as 1 or 10 percent human and either 90 or 99 percent bacterial."
Based on a study of the bacteria on 51 different people's hands, researchers found that the average person had more than 150 different species of bacteria living on his or her hands. But get this. The researchers summarize their findings in this way: "[W]e identified a total of 4,742 unique phylotypes [species of bacteria] across all of the hands examined. Although there was a core set of bacterial taxa commonly found on the palm surface, we observed pronounced intra- and interpersonal variation in bacterial community composition: hands from the same individual [i.e., the left and right hands--JAH] shared only 17% of their phylotypes, with different individuals sharing only 13%."
(Thanks to John's Corner of the World blog)