Knowledge that human diet and disease expanded together comes from a multitude of interlocking specialties that explain zoonoses
Physical anthropologists have found that plant and animal foods leave distinctive chemical signatures in human bones, as do proteins from marine and land animals.
- Paleoparasitologists, who prove that one man's mess is another's treasure, study coprolites, or preserved feces, for fossilized parasite eggs.
- Teams of archaeologists and paleobotanists sort through the garbage, ashes, and fossilized pollen at ancient campsites to learn which foods people ate.
- Paleopathologists examine bones and naturally preserved bodies to learn about ancient health and sickness; especially, zoonosis.
- Sedentism, farming, and animal husbandry came not in a transforming flash but gradually, and they coexisted with hunting-gathering from thousands of years.
- These developments came at different times and in different orders around the world.
- Full dependence on farming arrived in much of North America only a millennium ago.
- Where ever and when ever it came, it brought declines in health and an increase in zoonosis diseases.
- Agriculture had brought a stable, year-round food supply that could expand along with the population, but it made nutritional ills common.
- Poorly nourished people are considered to be an epidemic waiting to happen.
- By an exquisite misery of timing, the Neolithic vulnerability to disease came as people were exposed to a torrent of new pathogens.
Zoonoses apparently became greater with the domestication of animals
- Their wastes, garbage, and granaries drew scavengers, and they were domesticating many species, from horses to chickens, which bore hundreds of unfamiliar parasites.
- Each creature in the human orbit was exposed to infection by the others,
- The result for all was a potentially disastrous biological stew of zoonoses.
- Human's first animal companions were dogs, bred from the wolves and jackals that scvenged at the edge of hunters' camps.
- Deeply social, jackals and wolves could easily be raised to bond with humans.
- Intelligent, they could help men hunt, herd flocks, and act as alarms, companions, pets, and meals of last resort.
- Man and dog worked and played together, fed and slept together, urinated and defecated in the same areas.
- Cheek by jowl, skin by fur, they inevitably exchanged pathogens.
- As a result, humans ran higher risks of rabies and became hosts to new types of worms, to tick-borne diseases; such as, tick typhus, and to echinococcosis, a nasty infection that cause cysts of the liver and lungs.
A similar rise in zoonoses came with each domesticated species.
- Birds and pigs, like dogs, probably drew close to humans by scavenging around their camps and villages (the chicken and domesticated pigeon are descended, respectively, from the wild rock dove and the Asian wild jungle fowl).
- Scavenging rats and mice attracted cats, which were domesticated as pets, rodent killers, or both.
- Small mammals; such as, rabbits and guinea pigs were captured and bred for food.
- By about 4,000 years ago, horses, oxen, goats, and sheep had been tamed and bred to provide food, labor, and transportation.
- Modern city dwellers must keep in mind that these animals, with their viruses, bacteria, and worms, did not live in some distant reserve or hygienic compound.
- Humans and livestock often lived under the same roof and on the same floor of dirt or straw.
- People caught the animals' germs by breathing the same air and dust, touching the animals' wastes, butchering their bodies, using their wool and hides, and consuming their milk, eggs, or flesh.
- Many of the germs they met could not survive in humans, but others found a congenial second home: cats, dogs, ducks, hens, mice, rats, and reptiles all of which can carry Salmonella bacteria; which in humans cause mild to deadly intestinal infections.
- People have been catching zoonosis salmonellosis from poultry, eggs, and fecally contaminated water for 10,000 years; most recently, in the United States, because of crowded conditions in poultry farms and speeded-up, automated processing of chickens and eggs.
- Humans also acquired from livestock and pets a heavy load of helminths, or wormlike parasites.
- Such intruders range from the microscopic filarial worms that cause elephantiasis and African river blindness to yards-long intestinal hookworms and tapeworms.
- The effects ranged from moderate loss of blood and nutrients to disability and death.
- As hunters, humans had nibbled at the environment, occasionally catching from their prey such zoonoses as anthrax and trichinosis.
- As farmers, they bit off almost too much to digest.
- There are now more than a hundred common human helminths, and many uncommon ones.
- Most were acquired by contact with prey and domesticated animals.
Human diseases caused by animals: Zoonoses, Part 2.
Dracunculiasis or the Guinea worm infestation.
Unit of zoo-, -zoan words and definitions.
Unit about diseases and sickness at noso-, -nosis.