Microbes Shape Human History

Throughout most of human history, we were unaware of the microbial world. Microorganisms have shaped human culture since our earliest civilizations. latest new science news on Microbes Shape Human History  Yeasts and bacteria have made foods such as bread and cheese (Fig. 1.9A), as well as alcoholic beverages (discussed in Chapter 16). "Rock-eating" bacteria known as lithotrophs leached copper and other metals from ores exposed by mining, enabling ancient human miners to obtain these metals. The lithotrophic oxidation of minerals for energy generates strong acid, which accelerates breakdown of the ore. Today, about 20% of the world's copper, as well as some uranium and zinc, is produced by bacterial leaching. Unfortunately, microbial acidification also consumes the stone of ancient monuments (Fig. 1.9B) a process intensified by airborne acidic pollution. Management of microbial corrosion is an important field of applied microbiology. As humans became aware of microbes, our relationship with the microbial world changed in important ways (Table 1.2, pages 14-15). Early microscopists in the seventeenth and eighteenth centuries formulated key concepts of microbial existence, including their means of reproduction and death. In the nineteenth century, the "golden age" of microbiology, key principles of disease pathology and microbial ecology were established that scientists still use today. This period laid the foundation for modern science, in which genetics and molecular biology provide powerful tools for scientists to manipulate microorganisms for medicine and industry.

Microbial Disease Devastates Human Populations

Throughout history, microbial diseases such as tuberculosis and leprosy have profoundly affected human demo-graphics and cultural practices (Fig. 1.10). The bubonic plague, which wiped out a third of Europe's population in the fourteenth century, was caused by Yersinia pestis, a bacterium spread by rat fleas. Ironically, the plague-induced population decline enabled the social transformation that led to the Renaissance, a period of unprecedented cultural advancement. In the nineteenth century, the bacterium Mycobacterium tuberculosis stalked overcrowded cities, and tuberculosis became so common that the pallid appearance of tubercular patients became a symbol of tragic youth in European literature. Today, societies throughout the world have been profoundly shaped by the epidemic of acquired immunodeficiency syndrome (AIDS), caused by the human immunodeficiency virus (HIV). More than 36 million people are living with HIV infection today, and each year 2 million die of AIDS.
           Historians traditionally emphasize the role of war-fare in shaping human destiny; and the brilliance of leaders or the advantage of new technology, in determining which civilizations rise or fall. Yet the fate of human societies has often been determined by microbes. For example, much of the native population of North America was exterminated by smallpox introduced by European invaders. Throughout history, more soldiers have died of microbial infections than of wounds in battle. The significance of disease in warfare was first recognized by the British nurse and statistician Florence Nightingale (1820-1910) (Fig.1.11A). Better known as the founder of professional nursing, Nightingale also founded the science of medical statistics. She used methods invented by French statisticians to demonstrate the high mortality rate due to disease among British soldiers during the Crimean War. To show the deaths of soldiers due to various causes, she devised the "polar area chart" (Fig. 1.11B). Blue wedges represent deaths due to infectious disease, red wedges represent deaths due to wounds, and black wedges represent all other causes of death. Infectious disease accounts for more than half of all mortality. Before Nightingale's study, no one understood the impact of disease on armies, or on other crowded populations, such as cities. Nightingale's statistics convinced the British government to improve army living conditions and to upgrade the standards of army hospitals. In modern epidemiology, statistical analysis continues to serve as a crucial tool in determining the causes of disease.