Inter Species Negotiation
There is a theory that bacteria and viruses are negotiating with the hosts. Some parasites are very aggressive and kill their hosts fast to return to the soil to infect the next host and increase its territory (this is anthrax). We all have a huge number of bacteria and viruses in our intestinal tracts that help us digest our food, E. Coli is one of the bacteria although not all E. Coli is beneficial, E. Coli poisoning comes from fecal contamination by other animals; this is a partial negotiation.
A real strange bit is something I read about a flea circus operator. It takes someone about 6 months or so to train fleas to do things like pull tiny carts and other acts in a flea circus. The weird part is that the life of a flea is just a few weeks but it takes 6 months to train the fleas. What I think is going on is a negotiation where the fleas are given food (the flea circus operator typically lets the fleas feed on their arm) and protection which is a big part of the survival needs for fleas. The fleas in turn are able to perform and make money for the operator.
