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Unformatted text preview: n sustain themselves only in large dense populations that did not exist before agriculture, hence they are often termed ‘crowd diseases’. The mystery of the origins of many of these diseases has been solved by molecular biological studies of recent decades, demonstrating that they evolved from similar epidemic diseases of our herd domestic animals with which we began to come into close contact 10,000 years ago. Thus, the evolution of these diseases depended on two separate roles of domestication: in creating much denser human populations, and in permitting much more frequent transmission of animal diseases from our domesticates than from hunted wild animals. For instance, measles and tuberculosis arose from diseases of cattle, influenza from a disease of pigs and ducks1. An outstanding mystery remains the origins of smallpox: did it reach us from camels or from cattle? Crowd diseases paradoxically became agents of conquest, because exposed individuals acquired immune resistance from childhood
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This note was uploaded on 12/10/2012 for the course HORT 306 taught by Professor Staff during the Fall '08 term at Purdue.
- Fall '08