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The Effect of Internal Bacteria On the Human Body
meckdevil writes with this excerpt from the Miller-McCune magazine:
"In a series of recent findings, researchers describe bacteria that communicate in sophisticated ways, take concerted action, influence human physiology, alter human thinking, bioengineer the environment and control their own evolution. ... The abilities of bacteria are interesting to understand in their own right, and knowing how bacteria function in the biosphere may lead to new sources of energy or ways to degrade toxic chemicals, for example. But emerging evidence on the role of bacteria in human physiology brings the wonder and promise — and the hazards of misunderstanding them — up close and personal. ... Because in a very real sense, bacteria are us. Recent research has shown that gut microbes control or influence nutrient supply to the human host, the development of mature intestinal cells and blood vessels, the stimulation and maturation of the immune system, and blood levels of lipids such as cholesterol. They are, therefore, intimately involved in the bodily functions that tend to be out of kilter in modern society: metabolism, cardiovascular processes and defense against disease. Many researchers are coming to view such diseases as manifestations of imbalance in the ecology of the microbes inhabiting the human body. If further evidence bears this out, medicine is about to undergo a profound paradigm shift, and medical treatment could regularly involve kindness to microbes."
I know it's a bit of nit-picking in an otherwise fascinating and informative article, but this bit about bacteria directing their own evolution is quite unfounded and - I suspect - added to sensationalize a teeny bit.
Bacteria do engage in horizontal gene transfer, and so can shape their own genomes beyond relying on random mutation (which is perfectly reasonable and expected, given that us dumb eukaryotes have even figured out how to do that part pretty well). However, to suggest that the bacteria are making "intentional changes to their heritable scaffolding" with some kind of intelligence is anthropomorphizing a little overmuch, especially with this part: "To suggest that organisms as primitive as bacteria are capable of controlling their own evolution is obviously silly. Isn’t it?" Yes, bacteria can share genetic material and yes, some bits of material (plasmids!) seem developed almost explicitly to do this, but evidence of "intentions" or "control" behind their evolutionary direction is lacking. Bacteria share genes; the ones who pick up successful (eg, antibiotic resistance) genes survive and proliferate. Natural selection favors mobility of these situationally beneficial genes (and, one must note, only when they are beneficial; they otherwise drop rather rapidly out of the population) and the bacteria who harbor them, just like every other living thing on the planet.
Final note: no serious tree of life puts humans at the "apex." To do so is to misunderstand evolutionary theory: we are just as "evolved" as every other extant life form.
Sincerely,
A Pedantic Biologist
The real reason Americans are overweight is because they have been convinced to switch to a primarily sugar diet, and when that leads to being fat, they are told that they should starve themselves, try to make up for the effects of starvation with muscle building exercise, and eat an even higher ratio of sugar to other foods. This has been a vicious circle of ever worse diet since sometime around the early seventies when someone had the brilliant idea that since sugar has less calories for it's mass than fat, people will take in less calories and be thinner if they just eat sugar.
the eradication of all even potentially pathogenic bacteria living in the human host
You would die. You would completely keel over and be an ex-parrot.
You rely on bacteria just to get through the day, and *all* are potentially pathogenic. There is e. coli that lives in your gut happily digesting food and helping give you vitamin B, and then there is e. coli that can kill you dead via food poisoning. It only takes a few gene swaps to make one the other, and bacteria do this all the time on their own.
Ask myself? I did. I answered "he's a nut."
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BMO
Hate to quote Wikipedia, but: "Citation needed."
If you can quote Wikipedia, I can cite it.
The average human body, consisting of about 1013 (10,000,000,000,000 or about ten trillion) cells, has about ten times that number of microorganisms in the gut.
http://en.wikipedia.org/wiki/Human_flora#Gut_flora
Of course, bacteria are much smaller than animal cells. Its a bit like saying cars contain more dirt particles than functioning components.