1.1 What our ancestors knew  (Page 2/11)

Most people today, even those who know very little about microbiology, are familiar with the concept of microbes, or “germs,” and their role in human health. Schoolchildren learn about bacteria, viruses, and other microorganisms, and many even view specimens under a microscope. But a few hundred years ago, before the invention of the microscope, the existence of many types of microbes was impossible to prove. By definition, microorganism s , or microbe s , are very small organisms; many types of microbes are too small to see without a microscope, although some parasites and fungi are visible to the naked eye.

Humans have been living with—and using—microorganisms for much longer than they have been able to see them. Historical evidence suggests that humans have had some notion of microbial life since prehistoric times and have used that knowledge to develop foods as well as prevent and treat disease. In this section, we will explore some of the historical applications of microbiology as well as the early beginnings of microbiology as a science.

Fermented foods and beverages

People across the world have enjoyed fermented foods and beverages like beer, wine, bread, yogurt, cheese, and pickled vegetables for all of recorded history. Discoveries from several archeological sites suggest that even prehistoric people took advantage of fermentation to preserve and enhance the taste of food. Archaeologists studying pottery jars from a Neolithic village in China found that people were making a fermented beverage from rice, honey, and fruit as early as 7000 BC. P.E. McGovern et al. “Fermented Beverages of Pre- and Proto-Historic China.” Proceedings of the National Academy of Sciences of the United States of America 1 no. 51 (2004):17593–17598. doi:10.1073/pnas.0407921102.

Production of these foods and beverages requires microbial fermentation, a process that uses bacteria, mold, or yeast to convert sugars (carbohydrates) to alcohol, gases, and organic acids ( [link] ). While it is likely that people first learned about fermentation by accident—perhaps by drinking old milk that had curdled or old grape juice that had fermented—they later learned to harness the power of fermentation to make products like bread, cheese, and wine.

The iceman treateth

Prehistoric humans had a very limited understanding of the causes of disease, and various cultures developed different beliefs and explanations. While many believed that illness was punishment for angering the gods or was simply the result of fate, archaeological evidence suggests that prehistoric people attempted to treat illnesses and infections. One example of this is Ötzi the Iceman , a 5300-year-old mummy found frozen in the ice of the Ötzal Alps on the Austrian-Italian border in 1991. Because Ötzi was so well preserved by the ice, researchers discovered that he was infected with the eggs of the parasite Trichuris trichiura , which may have caused him to have abdominal pain and anemia. Researchers also found evidence of Borrelia burgdorferi , a bacterium that causes Lyme disease. A. Keller et al. “New Insights into the Tyrolean Iceman's Origin and Phenotype as Inferred by Whole-Genome Sequencing.” Nature Communications , 3 (2012): 698. doi:10.1038/ncomms1701. Some researchers think Ötzi may have been trying to treat his infections with the woody fruit of the Piptoporus betulinus fungus, which was discovered tied to his belongings. L. Capasso. “5300 Years Ago, the Ice Man Used Natural Laxatives and Antibiotics.” The Lancet , 352 (1998) 9143: 1864. doi: 10.1016/s0140-6736(05)79939-6. This fungus has both laxative and antibiotic properties. Ötzi was also covered in tattoos that were made by cutting incisions into his skin, filling them with herbs, and then burning the herbs. L. Capasso, L. “5300 Years Ago, the Ice Man Used Natural Laxatives and Antibiotics.” The Lancet , 352 no. 9143 (1998): 1864. doi: 10.1016/s0140-6736(05)79939-6. There is speculation that this may have been another attempt to treat his health ailments.