Dr. Ross D. E. MacPhee, Curator in the Division of Vertebrate
Zoology at the American Museum of Natural History
Jeff Saunders © AMNH
Dr. Ross D. E. MacPhee is a curator in the Division of Vertebrate
Zoology at the American Museum of Natural History. Dr. MacPhee's work
focuses on extinction, in particular the extinction of mammalian
species allegedly caused, or indirectly accelerated, by human behavior
within the last 40,000 years. Most recently, Ross' work has revolved
around the possibility that the extinction of large mammals at the end
of the Pleistocene Epoch (approximately 11,000 years ago) was caused
by diseases introduced through contact with humans or their commensals,
the organisms that depend on them or interact with them.
When Ross began his undergraduate degree in history at the University
of British Columbia, Canada, he never intended to study science.
His passion at the time was directed towards the study of human history
and his focus was the history of sub-Saharan Africa. However, all
students in the humanities were required to take a science course to
graduate. Because he felt he had no affinity for science, Ross elected
to take a course in physical anthropology, which he imagined to be less
scientifically rigorous than, say, a course in either chemistry or
physics. Much to his surprise, Ross soon found that he was engrossed in
the subject of physical anthropology, particularly in the areas of
morphology, evolution, and fossils.
Ross excelled in his physical anthropology class. As a result, the
professor, an archaeologist, invited him to work with him on an
archaeological dig during the summer break. This gave Ross his
initial experience of fieldwork. And for the first time he encountered
the subject of Pleistocene extinctions. His professor's research was
concerned with the early human presence in North America. It involved
trips to cave sites to look for evidence. These sites also contained
remains of extinct mammal species. The largest North American mammals
in existence today are bison and bears. Both animals are relatively
small compared to animals like the mammoths and giant sloths that lived
at the same time as the earliest known North American humans. Ross started
to develop a research interest in possible reasons behind the subsequent
extinction of these megafauna.
In graduate school, Ross carried out field research in eastern Nevada.
There he was astonished to find an abundance of fossilized remains of
such animals as American horses, huge condor-like birds, camels, and
sloths. Fascinated that these animals could have survived in the rough
country of eastern Nevada, Ross started to imagine how different the
landscape must have been when these animals were alive. A passion for
studying the causes of extinction of these early mammals took root.
Ross graduated with a Ph.D. in Physical Anthropology from the University
of Alberta, Canada, in 1977. In 1981 he took up a teaching position at
Duke University and continued his research. He became a curator at the
Museum in 1988. In addition, he is an adjunct senior scientist in the
CERC program at Columbia University and an associate professor at the
State University of New York at Stonybrook, New York. Ross is currently
series editor of Advances in Vertebrate Paleobiology, a continuing series
of books on different subject areas in paleontology.
Inspired by his initial fieldwork experience as a college freshman,
Ross continues to research the causes of megafauna extinctions at the
end of the Pleistocene Epoch. The two popular and accepted hypotheses
for the causes of Pleistocene extinctions - overhunting by humans or
reaction to sudden and extreme climate change - failed to fully convince
Dr. Ross D. E. MacPhee holds a mammoth tusk in the AMNH fossil collection.
Tina Gaud © AMNH
He proposed the hypothesis that the first peoples that entered
the Americas inadvertently imported pathogens that the native species
had no immunity against. These pathogens managed to infect new hosts,
thereby causing terrible plagues and enormous mortality. According to
his argument, in many cases the mortality was so great that extinction
ensued. Ross refers to such newly emergent diseases as "hyperdiseases."
What made them so dangerous was that the species of the New World had no
defenses against them.
How did he come up with this idea? In 1994, Ross read an article about
the Ebola virus in the New Yorker magazine. He was intrigued by the idea
that "new" diseases can strike (or "emerge") in new human hosts all the
time. The pathogens that cause newly emergent diseases in us, like Ebola,
are not necessarily new in an evolutionary sense; they could have existed
for hundreds of thousands of years in their original animal hosts. However,
conditions may change - as they do, for example, when humans clear out huge
tracts of rain forest, exposing themselves to animals and diseases they
had no previous contact with.
Ross then wondered if an emerging disease could have been the source of
the mammoths' demise. As you will learn in the course, Ross and Alex
Greenwood and their collaborators are trying to test this idea.
Ross has also long been interested in historical biogeography, or the
geographical distribution of different species over time. This area of
his research focuses in particular on the colonization of islands,
specifically the Greater Antilles, by mammal species: How did mammals
that live on islands, such as primates, sloths, and marsupials, get
there in the first place? No mean feat when you consider the fact
that these islands are separated from the mainland by hundreds of
kilometers of water. In the case of the Greater Antilles, Ross hypothesizes
that mammals were able to colonize these islands because they once formed
part of a land span that connected North and South America. He has been
successful in finding appropriate fossils that provide the evidence he
needs to support this hypothesis.
Ross enjoys the challenges of fieldwork which appeals to his practical
manner and solution-oriented bent. His research takes him to different
countries, often to remote locations, and always with a team of people.
There are matters of budget and time constraints to consider. Each
country has its own laws about collecting, which must be researched in
advance, and all necessary permits and visas have to be acquired in
advance of the trip. Setting up these trips and figuring out all the
logistical arrangements take specific skills and intricate planning.
Ross is forced to rely heavily on his wits in order to ensure that the
field trip runs smoothly and efficiently.
Wrangel Island, Siberia - one of the islands where Dr. MacPhee conducts
field research - contains an abundance of mammoth fossils. Here, Dr.
MacPhee holds a mammoth tusk that he collected in 1998.
Clare Flemming © AMNH
His modus operandi remains the same, no matter what his research topic.
When he remains unconvinced by conventional explanations to a situation,
Ross develops a theory that at first might seem implausible, like the
hyperdisease hypothesis. Ross believes you must continually question and
challenge existing explanations of phenomena and consider ways to test
them, or make them more understandable. He believes that when you do so,
you often find that the received wisdom turns out to be based on shifting
sands. His goal is to come up with an explanation that is not only more
comprehensive, but also more testable. To Ross, this is what science is
MacPhee, R. D. E., and D. A. Burney, "Dating of modified femora
of extinct dwarf Hippopotamus from southern Madagascar: implications
for constraining human colonization and vertebrate extinction events."
Journal of Archaeological Science, 18: 695-706. 1991.
MacPhee, R. D. E., and Grimaldi, D. A. "Mammal bones in Dominican
amber." Nature 380: 489-490. 1996.
Iturralde-Vinent, M. A., and R. D. E. MacPhee, "Age and Paleogeography
of Dominican Amber." Science 273:1850-1852. 1996
MacPhee, R. D. E., and P. A. Marx, "The 40,000 -year plague: humans, hyper-disease, and first-contact extinctions."
In S. M. Goodman and B. D. Patterson (eds.), Natural Change and Human Impact in Madagascar, pp. 169-217 (Smithsonian Institute Press, Washington, DC). 1997.
MacPhee, R. D. E., and Flemming, C., "Brown-eyed, milk-giving and Extinct: Losing mammals since AD 1500." Natural History
MacPhee, R. D. E., and Flemming, C., "Requiem aeternum: the last five
hundred years of mammalian species extinctions." In MacPhee, R. D. E.
(ed.) Extinctions in Near Time: Causes, Contexts, and Consequences,
pp. 333-372 (Kluwer Academic/Plenum Publishers: New York). 1999.
© 2000 American Museum of Natural History