"As soon as we are born, bacteria move in. They stake claims in our digestive and respiratory tracts, our teeth, our skin. They establish increasingly complex communities, like a forest that gradually takes over a clearing. By the time we’re a few years old, these communities have matured, and we carry them with us, more or less, for our entire lives. Our bodies harbor 100 trillion bacterial cells, outnumbering our human cells 10 to one. It’s easy to ignore this astonishing fact. Bacteria are tiny in comparison to human cells; they contribute just a few pounds to our weight and remain invisible to us.
It’s also been easy for science to overlook their role in our bodies and our health. Researchers have largely concerned themselves with bacteria’s negative role as pathogens: The devastating effects of a handful of infectious organisms have always seemed more urgent than what has been considered a benign and relatively unimportant relationship with “good” bacteria. In the intestine, the bacterial hub of the body that teems with trillions of microbes, they have traditionally been called “commensal” organisms — literally, eating at the same table. The moniker suggests that while we’ve known for decades that gut bacteria help digestion and prevent infections, they are little more than ever-present dinner guests.
But there’s a growing consensus among scientists that the relationship between us and our microbes is much more of a two-way street. With new technologies that allow scientists to better identify and study the organisms that live in and on us, we’ve become aware that bacteria, though tiny, are powerful chemical factories that fundamentally affect how the human body functions. They are not simply random squatters, but organized communities that evolve with us and are passed down from generation to generation. Through research that has blurred the boundary between medical and environmental microbiology, we’re beginning to understand that because the human body constitutes their environment, these microbial communities have been forced to adapt to changes in our diets, health, and lifestyle choices. Yet they, in turn, are also part of our environments, and our bodies have adapted to them. Our dinner guests, it seems, have shaped the very path of human evolution."
I want to scream at the top of my lungs and want this to be so true. I cannot wait to see the ripple effect, this is going to cause when it becomes a "self-evident" fact.
"Recently, for instance, evidence has surfaced that obesity may well include a microbial component. In ongoing work that is part of the Human Microbiome Project, researchers in Jeffrey Gordon’s lab at the Washington University School of Medicine in St. Louis showed that lean and obese mice have different proportions of microbes in their digestive systems. Bacteria in the plumper rodents, it seemed, were better able to extract energy from food, because when these bacteria were transferred into lean mice, the mice gained weight. The same is apparently true for humans: In December Gordon’s team published findings that lean and obese twins — whether identical or fraternal — harbor strikingly different bacterial communities. And these bacteria, they discovered, are not just helping to process food directly; they actually influence whether that energy is ultimately stored as fat in the body.
Even confined in their designated body parts, microbes exert their effects by churning out chemical signals for our cells to receive. Jeremy Nicholson, a chemist at Imperial College of London, has become a champion of the idea that the extent of this microbial signaling goes vastly underappreciated. Nicholson had been looking at the metabolites in human blood and urine with the hope of developing personalized drugs when he found that our bodily fluids are filled with metabolites produced by our intestinal bacteria. He now believes that the influence of gut microbes ranges from the ways in which we metabolize drugs and food to the subtle workings of our brain chemistry.
Scientists originally expected that the communication between animals and their symbiotic bacteria would form its own molecular language. But McFall-Ngai, an expert on animal-microbe symbiosis, says that she and other scientists have instead found beneficial relationships involving some of the same chemical messages that had been discovered previously in pathogens. Many bacterial products that had been termed “virulence factors” or “toxins” turn out to not be inherently offensive signals; they are just part of the conversation between microbe and host. The difference between our interaction with harmful and helpful bacteria, she says, is not so much like separate languages as it is a change in tone: “It’s the difference between an argument and a civil conversation.” We are in constant communication with our microbes, and the messages are broadcast throughout the human body."
Brain chemistry?? Wow, this is going to be fun!! I simply cannot comprehend why humans are so obsessed to be top of the chain instead being just a other lone branch in the tree of life? Wouldn't it be fun, if anyone who doesn't believe in animal-microbe symbiosis should come out honestly (sans the cognitive dissonance) and volunteer to remove those microbes from their body? Why do I have feeling they wouldn't line up to do that? Last time I checked, they eschew science but still go to doctor regularly and pop pills.
"Microbes in the gut, for instance, encounter bacteria that ride in on the food we consume. These visitors introduce a huge, unpredictable component that makes any determination of a core microbiome all the more difficult. In order to develop well-framed research questions, it’s crucial that microbiologist learn how to differentiate between co-evolved species and these itinerant “tourists.”
What we do know, however, is that our own personal microbiomes tend to be partly inherited — most of us pick up bacteria from our mothers and other family members early in life — and partly shaped by lifestyle. Ley, who has surveyed the gut bacteria of several species, says that diet is an important factor in determining the communities that live in an organism. Even with our processed foods and sterilized kitchens, Ley says, humans are not radically different from other animals that share our eating habits.
The individuality of each person’s microbiome might complicate the project of studying human-microbe relationships, but it also presents opportunities — for instance, the possibility that medical treatments could be tailored to a person’s particular microbiota. Much like a genetic profile, a person’s microbiome can be seen as a sort of natural identification tag. As David Relman, a microbiologist at Stanford University, puts it, “It’s a biometric — a signature of who you are and your life experience.” With support from the Human Microbiome Project, Relman is currently developing novel microfluidic devices that can isolate and sequence the genomes of individual bacterial cells. (Extracting genetic information from a complex sample normally mixes together hundreds if not thousands of unique species, so this single-microbe technology could well revolutionize the speed and scope of the entire field of metagenomics.) Personal microbiome information will also have implications for practical concerns, such as how we deploy antibiotics. Might those antibiotics we down at the first sign of an upset stomach be waging a microbes n unjustified civil war? Where do the massive quantities of antibiotics we feed to our livestock ultimately end up, and do they disrupt delicate ecological balances? We have lived with for our entire evolutionary history; how has the widespread use of chemicals that kill them changed those long-forged evolutionary relationships?"
On the lighter side, this is one more obvious case to eat less processed food and stick to natural evolutionary diet - more plants and less meat. Human-Microbe project is another website on the list of sites to check on a daily basis.
What a blow this would be to the human ego propogating their omnipotence? How can scientist convice this ( if it becomes a fact ) to people who don't even believe the theory of evolution? I bet, the future is going to fascinating one when science starts digging into this more. I haven't heard a better quote in a long lone time:
"Ironically, the human ingenuity that drives us to understand more about ourselves is revealing that we’re much less “human” than we once thought. "
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