Beasts of the Earth: Animals, Humans and Disease, by E. Fuller Torrey and Robert H. Yolken. New Brunswick, NJ, and London, UK: Rutgers University Press; 2005. 191 pages, $23.95 (cloth).
It is rare indeed that I get to review a book that grabs me, fascinates me, and impels me to read it. Such a book is Beasts of the Earth, which will definitely make you rethink the safety of our food supply, whether or not you should become a vegan or at the very least a vegetarian, and certainly whether or not to own pets. In my opinion, the intended audience should be any reader with an interest in the healthcare of human beings, including physicians, veterinarians, nurses, undergraduate and graduate students, public policy makers, farmers, ranchers, anyone involved with our food supply, as well as those responsible for homeland security and the prevention of bioterrorism.
The book traces the entire known record of human evolution and relates it to the evolution of bacteria, viruses, and protozoa, called zoonoses, which evolved and continue to evolve. We look at the fall of entire civilizations and the defeats of great armies through the lens of infectious disease. Short but fascinating chapters cover heirloom infections (microbes before the advent of humans), humans as hunters, as farmers, as villagers, as traders, as pet keepers, and as diners. Other chapters look at microbes from the modern food chain, with lessons from severe acute respiratory syndrome, influenza, and bird flu, as well as the coming plagues, with lessons learned from AIDS, West Nile Virus, and Lyme disease. The book includes an extensive bibliography and references, as well as notes, a glossary, an appendix and index. Especially helpful are the tables, charts, and graphs, which illustrate their key points (eg, p6, Figure 1-1, on types of animal-to-human transmission of microbes or p17, Table 2.1, on herpes viruses of humans and other animals). There are short, gripping chapters throughout, most of which leave you stunned and trying to process all that these authors have managed to pull together and present in such a digestible form. In Examining Zoonotic Diseases, we not only look at diseases of animals that can be transmitted to humans but also those which are transmitted from animal to animal before being transmitted to humans and those transmitted from humans to animals and back again.
Torrey and Yolken point out that human-animal contact began with the domestication of farm animals only 10,000 years ago. And while the presence of animals has had many positive effects on human beings (eg, people with pets usually have lower levels of cholesterol and lower blood pressure, show fewer signs and symptoms of depression, and tend to get more physical exercise), there is a dark side, a price to be paid for this closer contact with animals. There are many trends that have amplified the negative effects of animal contact on humans: the increasingly crowded planet, the shared living quarters, the overlapping ecosystems, the experimental surgical practices (including cross-species transplantation of organs and tissues), increased air travel, automated food processing, and threats of bioterrorism (which, by the way, has been practiced since ancient times).
Torrey and Yolken write in a vivid style for maximum impact. For instance,
animals took on new meaning for Paleolithic humans. Bison and horses, viewed on the plains, became the Paleolithic equivalent of a McDonald's golden arch. A passing gazelle may have evoked the same reaction that a sign for Kentucky Fried Chicken does today.(pp25-26)
They ask if humans domesticated wolves, or did wolves domesticate themselves?(p35) (This turns out to be a hot and burning controversy in the study of the domestication of animals). They point out that
smallpox also figures prominently as a potential microbe for bioterrorism and was one of the first microbes so used; in 1763 British officer Lord Jeffrey Amherst ordered his troops to give smallpox-infected blankets to Native Americans to deliberately infect them(p41)
(something that was also done by Americans to plain's Indians). The authors also point out that "Americans now spend some $47 billion per year on their pets, more than the gross national product of Costa Rica, Guatemala, Ecuador, Ivory Coast, Ethiopia, Croatia, Bulgaria or Lebanon."(p74) For this kind of money, we could be providing rich healthcare benefits to every single person in the United States, who is now not covered by healthcare insurance. They also say "it is likely that the increase in resistance to antibiotics is due to the widespread administration of antibiotics to animals in the food chain."(p100) Furthermore,
undercooking may occur, for example, when poultry is stuffed and then cooked at a low temperature. Precooked chickens purchased at stores have also been indicted in some outbreaks (of salmonella poisoning)[horizontal ellipsis]. The largest reason for the increasing incidence of salmonella infections, however, is the greater mechanization of the poultry business.(pp102-103)
Pigs, it turns out, are the perfect breeding pools for influenza viruses that are then passed on to human beings.(p116) Another interesting thought from these authors is
it is not generally appreciated that big cities are a relatively recent phenomenon[horizontal ellipsis]. Megacities, with populations of ten million or more, are new [horizontal ellipsis] global warming could lead to the reemergence in such cities as New York, Rome, and Tokyo of the protozoa and viruses that cause malaria, yellow fever, and dengue. Other infectious disease whose spread would be favored by a rise in temperature include viral encephalitis, schistosomiasis, and leishmaniasis.(p131)
Most alarming of all, Torrey and Yolken point out that human beings represent only a tiny fraction of the known species of mammals and that we know next to nothing at all about the microbes which infect other mammals, to say nothing of the microbes that infect birds, reptiles, amphibians, fish, or other forms of life.(p133) They say that historically there has been virtually no research collaboration whatsoever between veterinarians and physicians of infectious diseases. They suggest that veterinary and medical personnel need to be coordinated in a single research center and that we need to step up the autopsy rate (which has fallen from 41% in 1964 to only 5% today) to detect disease; that parents must protect their children from intimate contact with pets and other animals and we must be sure to clean and cook foods appropriately; that we must immediately regulate the importation of exotic species, currently virtually unregulated; and that pet store owners have an obligation to educate the pet-buying public on safety precautions of pet ownership, such as scrupulous hand washing.
They also provide 10 rules for keeping safer pets. Select the safest possible pets. Avoid exotic pets. Pets are safest for adults and least safe for young children. Newborn pets are riskier that adult pets (due to some infections which are harbored exclusively by newborn animals). Teach children not to harass dogs or cats or to pet stray animals. Demonstrate good hygiene practices around pets. Keep food preparation and pets strictly separated. Keep children's sandboxes covered when not in use. Keep pets in good health. And remember that we only understand a tiny fraction of the diseases that spread from pets to humans.
I would highly recommend this book to anyone with an interest in evolution, healthcare, bioterrorism, infectious disease, anthropology, sociology, and more. I found it truly fascinating and it has changed my understanding of the world around me. Nearly every page contains a gem or interesting idea that leapt out at me. It is written in a flowing style that reads almost like a novel. And I propose that since 9/11, this is one important book with which all of us should become familiar.
-Marcie Parker, PhD, CFLE
President and CEO, Parker and Associates, Excelsior, Minnesota