I found this interesting article on the evolution of symbiotic bacteria in the human gut in PLoS. A good summary article accompanies it. Some interesting implications of the work are that considerations for the evolution of 'our' bacterial genomes should be considered when looking at human evolution. In fact a hot topic in the blogosphere is the possibility of a human microbiome project. (check out this link for sure.) Without these bacterial communities we would not be able to acquire much of the energy from cellulose that we get when we eat plant material. I would assume then, and it is mentioned in the summary, that perhaps the makeup of the bacteria in the human gut would be influenced by the hosts diet. Would a vegatarian then have more bacteria able to break down cellulose for example thus making the host a more efficient user of plant energy? Since we humans lack the complex digestive system of the ruminant, as we are evolved to be omnivorous, perhaps vegetarians should consider eating their own feces to more efficiently extract energy from plant matter.
Coprophagia, or eating your own poop, is a term first brought to my attention by fellow bayblabite, Alfred Russel Wallace. My pet bunny practices this behavior, however, I have, thankfully, rarely noticed it doing this. One of the best sites I have seen on the subject of bunny poop eating is a must see and informative. For example, the site points out, if you overfeed your bunny you might inhibit coprophagia and malnurish your pet. The disgustingly cute animated gifs add to the atmosphere of this site.