Cannibalism: A Perfectly Natural History(72)

The plague was over. Or so it seemed.



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45 Admittedly, “Swiss cheesiform” doesn’t have the same ring.



46 The Territory of New Guinea was administered by Australia from 1920 until 1975.



47 Once attached to their specific antigens, the antibodies either interrupt the normal function of the foreign cell or virus, or mark it for destruction by other cells of the immune system like macrophages.



48 For the record, Diamond’s stance is that cannibalism was a widespread practice throughout human history.



49 We now know that the symptoms may not appear until five decades after exposure.





18: Mad Cows and Englishmen


Unfortunately, the custom of consuming human flesh, like exotic sexual practices, polygamy, and other alien habits, raises violent, unintellectual passions in the Western scholars who study them.

— Brian Fagan, The Aztecs, 1984

In the 1980s, researchers in the United Kingdom, like those in New Guinea, were also seeking to explain how a strange form of spongiform encephalopathy was being transmitted, and where it had come from. Like their New Guinea counterparts, they struck pay dirt after making a connection to diet—in this case, after examining the diets of English dairy cows.

In order to maximize milk production, farmers typically supplemented livestock diets with protein—most often in the form of soybean products. In England, however, where there is no substantial soybean agriculture, using soy as an additive would have been an expensive proposition. Because of this, in the 1940s meat and dairy industries in the UK began to render the waste products of livestock slaughter into an innocent-sounding material they called “meat and bone meal.” Noting the cost-saving benefits, the U.S. and other nations followed suit. In addition to ingredients like bones, brains, spinal cords, heads, hooves, udders, and viscera, the recipe du jour for meat and bone meal also called for the bodies of sick animals (including poultry, pigs, sheep, and so-called downer cattle)50 that had been deemed unfit for human consumption. This gruesome mess was sent off to the “knacker’s yard,” a British slang term for a rendering plant. During the rendering process, the above-mentioned goodies were ground, cooked, and dried into a greyish, feces-scented powder which was sold as a source of dietary protein, calcium, and vitamins for dairy cows, beef cows, pigs, and poultry.

Although a comparison of livestock-feeding practices with the ritualized consumption of relatives by the Fore seems to be a bit of a stretch, in reality there is an important similarity. In the case of the Fore, ritual cannibalism of kuru victims exposed practitioners to a deadly infective agent. And although nobody knew it at the time, beginning in the 1940s, livestock were exposed to similar pathogens after being forced to consume dietary supplements derived (at least partially) from sickened members of their own species.

But why had the Bovine Spongiform Encephalopathy (or BSE) epidemic struck so suddenly four decades later? The livestock industry had been using meat and bone meal for 40 years and nothing like this had ever happened before.

In searching for answers, the British government enlisted epidemiologist John Wilesmith, who examined the records (where they existed) of rendering plants across the UK. He soon determined that several modifications related to the rendering process had been instituted in the early 1980s. The first was that most of the plants had discontinued the separation of tallow (a creamy fat used to made candles and soap) from the material being converted into meat and bone meal. Previously, dangerous solvents had been used to extract tallow during the rendering process, but after a massive industrial explosion in 1974, safety measures were introduced regarding the handling of solvents in the workplace. Rather than deal with the expensive modifications mandated by the new rendering industry regulations, all but two of the plants chose to abandon the tallow extraction process altogether. As a result, substances that had once been removed by the solvent extraction process now remained in the resulting meat and bone meal. Presumably, these substances included the infective—and still unidentified—agent causing Bovine Spongiform Encephalopathy. There was more, though.

Wilesmith and his team learned from herdsmen that several recent changes had been made to livestock diets. The first was a significant increase (from 1 percent to 12 percent) in the amount of meat and bone meal added to dairy cow feed. Calves were also receiving the protein supplement at an earlier age. As in other spongiform encephalopathies, there appeared to be a direct correlation between the amount of contaminated material ingested and the likelihood of contracting BSE. Similarly, the incubation period for BSE was apparently shorter in younger animals. In theory, then, before industry-wide changes in diet were implemented, calves received less of the contaminated supplement and did not start ingesting it until later in their lives. As a consequence, infected animals would have been slaughtered before they had a chance to get sick.

The results of Wilesmith’s epidemiological study were presented to ministry officials in May 1988. He told them that the BSE problem could be traced to the popular nutritional supplement that had been contaminated with sheep scrapie. This material had subsequently been fed to cows, sickening them. In retrospect, Wilesmith’s detective work was remarkably efficient, but ultimately his belief that BSE and scrapie were one in the same disease would place British consumers in peril for over a decade.