The Power of Plagues. Irwin W. Sherman

The Power of Plagues - Irwin W. Sherman


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and a gatherer. H. habilis was also a hunter who made and used stone tools: simple stone flakes, scrapers and “choppers” that were chipped from larger stones (Fig. 2.3a). (These stone tools, first found in Africa’s Olduvai Gorge, are called Oldowan tools.) The fashioning of tools suggests a great leap in human intelligence and begins the technological changes that would forever mark Homo as a tool maker and a tool user. H. habilis used the flake tools to cut up the carcasses of the animals that were killed; these were transported to a home base where the meat was fed upon. H. habilis, with a somewhat larger brain, was “smarter” than A. afarensis, but the fossil finds tell us nothing of the numbers of individuals, whether there was division of labor among males and females, or anything about their behavior. We speculate, however, that there were 50 to 60 individuals in a group living in an area of 200 to 600 square miles. We imagine that H. habilis lived at the edge of shallow lakes and in crude rock shelters.

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      There is no fossil record of the parasites that afflicted H. habilis since their soft bodies have disintegrated over time, but we do know that with meat eating came an increase in parasitism. As these nomadic hunters encountered new prey, they met new parasites and new vectors of parasites. The result was zoonosis; that is, animal infections were transmitted to humans. What were these zoonotic infections? We surmise that the parasites of H. habilis were those acquired from the wild animals that were killed and scavenged. The butchered meat might have had parasites such as the bacteria anthrax and tetanus, the roundworm that causes trichinosis, and a variety of intestinal tapeworms. H. habilis would probably have been bitten by mosquitoes, ticks, mites, and tsetse flies, and probably also had head lice. H. habilis also may have suffered from viral diseases such as the mosquito-transmitted yellow fever, as well as non-vector-borne viruses that cause hepatitis, herpes, and colds, and he may have had spirochete infections such as yaws. It is doubtful, but H. habilis could also have been infected with the parasites that cause sleeping sickness, malaria, and leprosy. They certainly must have been infected with filaria, pinworms, and blood flukes, but probably did not have typhus, mumps, measles, influenza, tuberculosis, cholera, chickenpox, diphtheria, or gonorrhea. At the time when H. habilis roamed the African savannah, the human population was quite small, consisting of about 100,000 individuals, and we expect that rates of human-to-human transmission of parasites were low.

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      When the populations of H. erectus left Africa, some of their parasites went with them, but only those that could be transmitted directly from person to person. Those vectors that remained restricted to Africa, such as the species of mosquito, snail, and fly that transmit diseases such as filariasis, blood fluke disease, and sleeping sickness, respectively, did not follow the migratory path. Indeed, even today they remain diseases that are characteristic of Africa. But as H. erectus encountered new environments with new kinds of animals, they were subjected to sources of new parasites; with an increase in the number of humans living in more-restricted geographic environments, the probability for large-scale infections was enhanced.

      In western Europe, human skeletons were found first in the Neander Valley of Germany in 1856; they were called Neanderthals. Subsequently, Neanderthal fossils were found in the Middle East and parts of western Asia. They date from between 190,000 and 29,000 years ago. Some archeologists have classified them as a separate species,

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