Substantial evidence shows that when a host such as humans start living
closely in large settlements microorganisms are not only more easily
transmitted but may also increase their pathogenicity without risking their
own existence.

1  Cohen MN. Health and the Rise of Civilization. New Haven: Yale
University Press, 1989.
2  Macfarlane B, White DO. Natural history of infectious disease.
Cambridge, Cambridge University Press, 1972.

Staffan Lindeberg, M.D. Ph.D.
Dept of Community Health Sciences, Lund University, Mailing address:
Primary Health Care Centre, Sjobo, S-22738 Sweden, +46 416 28140, Fax +46
416 18395 <[log in to unmask]>
http://www.panix.com/~paleodiet/lindeberg/