Patterns of Infection and Patterns of Evolution: How a Malaria Parasite Brought "Monkeys and Man" Closer Together in the 1960s.

Rachel Mason Dentinger

doi:10.1007/s10739-015-9421-8

Abstract

In 1960, American parasitologist Don Eyles was unexpectedly infected with a malariaparasite isolated from a macaque. He and his supervisor, G. Robert Coatney of the National Institutes of Health, had started this series of experiments with the assumption that humans were not susceptible to "monkey malaria." The revelation that a mosquito carrying a macaque parasite could infect a human raised a whole range of public health and biological questions. This paper follows Coatney's team of parasitologists and their subjects: from the human to the nonhuman; from the American laboratory to the forests of Malaysia; and between the domains of medical research and natural history. In the course of this research, Coatney and his colleagues inverted Koch's postulate, by which animal subjects are used to identify and understand human parasites. In contrast, Coatney's experimental protocol used human subjects to identify and understand monkey parasites. In so doing, the team repeatedly followed malaria parasites across the purported boundary separating monkeys and humans, a practical experience that created a sense of biological symmetry between these separate species. Ultimately, this led Coatney and his colleagues make evolutionary inferences, concluding "that monkeys and man are more closely related than some of us wish to admit." In following monkeys, men, and malaria across biological, geographical, and disciplinary boundaries, this paper offers a new historical narrative, demonstrating that the pursuit of public health agendas can fuel the expansion of evolutionary knowledge.

Highlights

Using Parasitic Infection to Reconstruct Evolutionary RelationshipsWhen Eyles was infected with ‘‘monkey malaria’’ in 1960, his research program was already based upon a basic assumption of symmetry between humans and other primates
In 1960, parasitologist Don Eyles was in the midst of a series of malaria experiments on rhesus macaques
One inadvertent laboratory infection did not necessarily imply a public health threat, but it did present a string of perturbing questions to Coatney, Eyles, and their colleagues: Could mosquito vectors reliably transmit monkey malaria to human subjects? Could they perhaps even transmit the parasite between human subjects? Did human infection with monkey malaria happen in Malaysia, where the monkey parasite P. cynomolgi was first isolated? Pursuing these questions would require the efforts of multiple teams of parasitologists, working in the United States and Malaysia, conducting human experimentation, opportunistic collection, and ecological field trials

Summary

Using Parasitic Infection to Reconstruct Evolutionary Relationships

When Eyles was infected with ‘‘monkey malaria’’ in 1960, his research program was already based upon a basic assumption of symmetry between humans and other primates. Parasitology was a domain where the traditions of natural history and taxonomy converged (and sometimes conflicted) with laboratory- and field-based medical research Following primates and their malaria parasites as they move across this historical domain provides an opportunity to analyze how these different modes of science were pursued in concert and how their interaction shifted the taxonomic and disease identities and evolutionary relationships of the organisms that parasitologists studied. Instead of setting humans and their associated parasites apart from all nonhuman primates and their parasites, Garnham’s tree drew the malaria parasites of apes and humans into close proximity, while placing those of monkeys at a greater evolutionary distance He drew on contemporary paleoanthropological research, including serological methods, when he wrote: ‘‘There is evidence today that the chimpanzee and gorilla are closer to man than the other so-called higher apes,’’ arguing that the clustering apparent in patterns of malaria infection could be used to bolster this hypothesis While the versification of this dual insight added a personal note to Coatney’s case, it was, at the same time, just an extension of the decades of research that had preceded his own, which had linked together medical and evolutionary questions and research agendas in the pursuit of parasitology

Conclusion

Open Access