Today's issue of Science magazine has several articles on the human gut, the
abstract of one of which appears below. I encourage you to read the articles
and increase your knowledge in this important area.

Science, Vol 307, Issue 5717, 1915-1920 , 25 March 2005
Host-Bacterial Mutualism in the Human Intestine
Fredrik Beckhed, Ruth E. Ley, Justin L. Sonnenburg, Daniel A. Peterson, Jeffrey
I. Gordon

The distal human intestine represents an anaerobic bioreactor programmed with
an enormous population of bacteria, dominated by relatively few divisions that
are highly diverse at the strain/subspecies level. This microbiota and its
collective genomes (microbiome) provide us with genetic and metabolic
attributes we have not been required to evolve on our own, including the
ability to harvest otherwise inaccessible nutrients. New studies are revealing
how the gut microbiota has coevolved with us and how it manipulates and
complements our biology in ways that are mutually beneficial. We are also
starting to understand how certain keystone members of the microbiota operate
to maintain the stability and functional adaptability of this microbial organ.

Tom Billings