The Greatest Benefit to Mankind. Roy Porter

and death become the human condition, as a consequence of original sin. The Bible closes with foreboding: ‘And I looked, and behold a pale horse’ prophesied the Book of Revelation: ‘and his name that sat on him was Death, and Hell followed with him. And power was given unto them over the fourth part of the earth, to kill with sword, and with hunger, and with death, and with the beasts of the earth.’

      Much later, the eighteenth-century physician George Cheyne drew attention to a further irony in the history of health. Medicine owed its foundation as a science to Hippocrates and his successors, and such founding fathers were surely to be praised. Yet why had medicine originated among the Greeks? It was because, the witty Scotsman explained, being the first civilized, intellectual people, with leisure to cultivate the life of the mind, they had frittered away the rude vitality of their warrior ancestors – the heroes of the Iliad – and so had been the first to need medical ministrations. This ‘diseases of civilization’ paradox had a fine future ahead of it, resonating throughout Nietzsche and Freud’s Civilization and its Discontents (1930). Thus to many, from classical poets up to the prophets of modernity, disease has seemed the dark side of development, its Jekyll-and-Hyde double: progress brings pestilence, society sickness.

      Stories such as these reveal the enigmatic play of peoples, plagues and physicians which is the thread of this book, scotching any innocent notion that the story of health and medicine is a pageant of progress. Pandora’s box and similar just-so stories tell a further tale moreover, that plagues and pestilence are not acts of God or natural hazards; they are of mankind’s own making. Disease is a social development no less than the medicine that combats it.

      In the beginning … Anthropologists now maintain that some five million years ago in Africa there occurred the branching of the primate line which led to the first ape men, the low-browed, big-jawed hominid Australopithecines. Within a mere three million years Homo erectus had emerged, our first entirely upright, large-brained ancestor, who learned how to make fire, use stone tools, and eventually developed speech. Almost certainly a carnivorous hunter, this palaeolithic pioneer fanned out a million years or so ago from Africa into Asia and Europe. Thereafter a direct line leads to Homo sapiens who emerged around 150,000 BC.

      The life of early mankind was not exactly arcadian. Archaeology and palaeopathology give us glimpses of forebears who were often malformed, racked with arthritis and lamed by injuries – limbs broken in accidents and mending awry. Living in a dangerous, often harsh and always unpredictable environment, their lifespan was short. Nevertheless, prehistoric people escaped many of the miseries popularly associated with the ‘fall’; it was later developments which exposed their descendants to the pathogens that brought infectious disease and have since done so much to shape human history.

      The more humans swarmed over the globe, the more they were themselves colonized by creatures capable of doing harm, including parasites and pathogens. There have been parasitic helminths (worms), fleas, ticks and a host of arthropods, which are the bearers of ‘arbo’ (arthropod-borne) infections. There have also been the micro-organisms like bacteria, viruses and protozoans. Their very rapid reproduction rates within a host provoke severe illness but, as if by compensation, produce in survivors immunity against reinfection. All such disease threats have been and remain locked with humans in evolutionary struggles for the survival of the fittest, which have no master plot and grant mankind no privileges.

      Despite carbon-dating and other sophisticated techniques used by palaeopathologists, we lack any semblance of a day-to-day health chart for early Homo sapiens. Theories and guesswork can be supported by reference to so-called ‘primitive’ peoples in the modern world, for instance Australian aborigines, the Hadza of Tanzania, or the !Kung San bush people of the Kalahari. Our early progenitors were hunters and gatherers. Pooling tools and food, they lived as nomadic opportunistic omnivores in scattered familial groups of perhaps thirty or forty. Infections like smallpox, measles and flu must have been virtually unknown, since the micro-organisms that cause contagious diseases require high population densities to provide reservoirs of susceptibles. And because of the need to search for food, these small bands did not stay put long enough to pollute water sources or accumulate the filth that attracts disease-spreading insects. Above all, isolated hunter-foragers did not tend cattle and the other tamed animals which have played such an ambiguous role in human history. While meat and milk, hides and horns made civilization possible, domesticated animals proved perennial and often catastrophic sources of illness, for infectious disease riddled beasts long before spreading to humans.

      Our ‘primitive’ ancestors were thus practically free of the pestilences that ambushed their ‘civilized’ successors and have plagued us ever since. Yet they did not exactly enjoy a golden age, for, together with dangers, injuries and hardships, there were ailments to which they were susceptible. Soil-borne anaerobic bacteria penetrated through skin wounds to produce gangrene and tetanus; anthrax and rabies were picked up from animal predators like wolves; infections were acquired through eating raw animal flesh, while game would have transmitted the microbes of relapsing fever (like typhus, a louse-borne disease), brucellosis and haemorrhagic fevers. Other threats came from organisms co-evolving with humans, including tapeworms and such spirochaetes as Treponema, the agent of syphilis, and the similar skin infection, yaws.

      Hunter-gatherers being omnivores, they were probably not malnourished, at least not until rising populations had hunted to extinction most of the big game roaming the savannahs and prairies. Resources and population were broadly in balance. Relative freedom from disease encouraged numbers to rise, but all were prey to climate, especially during the Ice Age which set in from around 50,000 BC. Famine took its toll; lives would have been lost in hunting and skirmishing; childbirth was hazardous, fertility probably low, and infanticide may have been practised. All such factors kept numbers in check.

      For tens of thousands of years there was ample territory for dispersal, as pressure on resources drove migration ‘out of Africa’ into all corners of the Old World, initially to the warm regions of Asia and southern Europe, but then farther north into less hospitable climes. These nomadic ways continued until the end of the last Ice Age (the Pleistocene) around 12,000–10,000 years ago brought the invention of agriculture.

      Contrary to the Victorian assumption that farming arose out of mankind’s inherent progressiveness, it is now believed that tilling the soil began because population pressure and the depletion of game supplies left no alternative: it was produce more or perish. By around 50,000 BC, mankind had spilled over from the Old World to New Guinea and Australasia, and by 10,000 BC (perhaps much earlier) to the Americas as well (during the last Ice Age the lowering of the oceans made it possible to cross by land bridge from Siberia to Alaska). But when the ice caps melted around ten thousand years ago and the seas rose once more, there were no longer huge tracts of land filled with game but empty of humans and so ripe for colonization. Mankind faced its first ecological crisis – its first survival test.

      Necessity proved the mother of invention, and Stone Age stalkers, faced with famine – elk and gazelle had thinned out, leaving hogs, rabbits and rodents – were forced to grow their own food and settle in one place. Agriculture enhanced mankind’s capacity to harness natural resources, selectively breeding wild grasses into domesticated varieties of grains, and bringing dogs, cattle, sheep, goats, pigs, horses and poultry under control. This change had the rapidity of a revolution: until around 10,000 years ago, almost all human groups were hunter-gatherers, but within a few thousand years cultivators and pastoralists predominated. The ‘neolithic revolution’ was truly epochal.

      In the fertile crescent of the Middle East, wheat, barley, peas and lentils were cultivated, and sheep, pigs and goats herded; the neolithic peoples of south-east Asia exploited rice, sweet potatoes, ducks and chickens; in Mesoamerica, it was maize, beans, cassava, potatoes and guinea pigs. The land which a nomadic band would have stripped like locusts before moving on was transformed by new management techniques into a resource capable of supporting thousands, year in, year out. And once agriculture took root, with its systematic planting of grains and lentils and animal husbandry, numbers went on spiralling, since more could be fed. The labour-intensiveness of clearing woodland and scrub, weeding fields, harvesting crops and preparing food encouraged population growth and the formation of social hierarchies, towns, courts and kingdoms.