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Evolutionary Medicine
By
Christine H. O’Toole.
Carnegie
Museum of Natural History scientists will soon be teaching
Pitt medical students lessons in where they came from—and
why, when treating and diagnosing disease, evolution
matters.
Among those looking forward to the unveiling of Fierce
Friends, Carnegie Museum of Art’s examination of
the changing depictions of animals in 18th- and 19th-century
art (see page 16), are the scientists of Carnegie Museum
of Natural History next door, who dig the deepest roots
of the human family tree. The
exhibition provocatively conveys how man’s increased
understanding of the natural world informed the artists
of the time. And it hints at how Darwin’s theories
about our animal ancestry—introduced in the late
19th century—would totally rearrange the natural
history of humankind and, years later, would still roil
the culture.
“
The key event that led to our change in perspective about
human evolution is the shocking surprise that humans are
animals,” says Chris Beard, head of the museum’s
Section of Vertebrate Paleontology. “That's a revolution
that continues to the present day and has still not been
completely digested by society at large, by artists, and
even by scientists.”
Contemporary medical issues, from the origins and transmission
of disease to an aching back, have roots that go back millions
of years in human and animal development—an astonishing
connection for those who associate evolution with the cave
man, and medicine with penicillin. And soon, Museum of
Natural History scientists will be illuminating that connection
in a course created for University of Pittsburgh medical
students on the natural history of medicine.
“
I have long wanted to teach our medical students that diseases
and disorders can only be fully understood in a social,
cultural, and historical context,” says Arthur S.
Levine, M.D., senior vice-chancellor for the health sciences
and dean of the medical school. “Without such a robust
context, physicians and medical researchers may miss critical
connections that help us to understand the origins of human
illness and how this knowledge may lead to new ideas for
prevention and treatment.
“
The museum’s new course is our next step in integrating
contemporary medicine with the whole history of biology,” Levine
adds. “Moreover, it weds two of the country’s
most outstanding institutions—the medical school
and the Museum of Natural History—in a relationship
that promises new and rich opportunities for scientific
as well as educational collaboration.”
Bill DeWalt,
director of Carnegie Museum of Natural History, marvels
at the collective brainpower the course will feature
on both sides of the lectern: “It’s exciting
to both institutions to be collaborating at this level,” DeWalt
says. “Our scientists are internationally renowned
for their work delving into the evolution of life in all
its forms. And they’ll be sharing their knowledge
with the best and brightest future physicians and researchers
in this country. Only great things could come of that.”
Old-Fashioned Biology
The decision to broaden the Pitt curriculum stems from
parallel research questions in natural history and medicine.
Beard
explains: “We live today at a sort of great
harmonic convergence of biology—where old-fashioned
biology, like what we do at the museum, is suddenly becoming
more relevant to modern biology. We’re starting to
put together genetic aspects of evolution with what we
know about the fossil record and anatomical change through
time. And physicians are becoming more aware that medicine
itself is evolutionary; that disease-causing microbes are
constantly evolving.
“
Natural Selection is the only explanation for why certain
strains of bacteria become immune to antibiotics,” says
Beard—a point, he notes that shouldn’t be lost
as we grapple with some vexing health issues. “People
are worried about whether bird flu virus is going to mutate.
So, an evolutionary perspective, which is usually absent
from most medical school curricula, needs to be re-inserted.
It’s critical.”
John Lazo, M.D., the Allegheny
Foundation Professor of Pharmacology and Director of the
Drug Discovery Institute
(and a Museum of Natural History board member), agrees. “These
scientists have a vehicle that allows us to ask questions
about biology that are unique in terms of medical schools,” he
says. “We typically use just a few species, like
mice and zebrafish, to ask profound questions about diseases
and ways to treat them. But they have hundreds of thousands
of species—some of the finest collections in the
world.”
John Wible, curator of mammals for the museum,
sees the museum’s holdings as a valuable medical
resource: “We
have a very broad-based collection of recent mammals that
can be useful in teaching topics relevant to medicine,
such as the evolution of the brain.”
Physician, Know Thyself
It’s not only their specimens that Carnegie Museum
scientists will offer to Pitt’s 600 doctors in training,
but their broad scientific perspective, too. Their course,
entitled the Natural History of Medicine, will be presented
as an elective beginning this year. (Medical students are
also required to complete a multi-year mentored scholarly
project and may choose a topic related to the museum’s
strengths.)
The course instructors are some of the museum’s
most eminent researchers. Chris Beard and his colleague
Zhe-Xi
Luo, the museum’s associate director of science and
collections, will join John Wible and Sandra Olsen, curator
of anthropology, as instructors. Beard’s research
focuses on the evolution of primates; Luo, who currently
teaches a course on evolution at the University of Pittsburgh,
has co-authored groundbreaking research on early mammals
with Wible; and Olsen has explored 5,500-year-old pastoral
cultures (see Face Time).
The scientists say that
enriching medical students’ understanding
of natural history isn’t merely esoteric: it will
make them better doctors, allowing them to better explain
medical conditions to patients and determine treatments.
“
When our ancestors decided to rise up on their hind legs
and start walking around like us, instead of on all fours,
that was a good thing because it allowed us to do things
with our hands,” Beard explains. “But at the
same time, it made it hard for women to give birth. And
it also leads to chronic lower back pain, hernias, and
all kinds of orthopedic problems with knees and ankles.”
And
athletes, take note: “Our arms have evolved the
capacity for enormous mobility at the shoulder joint from
(yes) hanging from branches,” Beard explains. “That
allows modern humans to pitch baseball, which is something
the average mammal, such as dogs and cats, can’t
do. As quadrapeds, their shoulder joints are built for
stability, even if that means they lack the full range
of motion that we have. The price we pay for our wide range
of shoulder mobility is a big decrease in joint stability,
which makes us prone to injury, especially rotator cuff
injuries. By making students aware of the evolutionary
history behind these things, hopefully we’ll make
them better doctors—more engaged and more curious.”
Lazo
puts it in clinical context: “Anatomy can be
dry. You can memorize, or you can make the connection.
Take the eye: you can describe it, or you can show how
it evolved. Discussing why nocturnal animals can see better,
then looking at cones and rods in their eyes, you can compare
animal to human. Then you can
discuss macular degeneration [deterioration of the retina]
and really understand the process.”
Prehistoric Diseases
and Early Cures
When Lazo, who co-directs the molecular therapeutics/drug
discovery program at the University of Pittsburgh Cancer
Institute, presents his latest research findings, he
typically includes a favorite slide given to him by the
Museum of
Natural History’s paleontologists: a photograph
of 150-million-year-old cancerous tumor from a Jurassic
dinosaur. “It’s
always my second slide—a free ad for the museum,” he
jokes. “But it makes the point. When you see a
150-million-year-old tumor, you realize cancer has been
around for a long time.
It’s not just because we smoke.”
Carnegie
Museum scientists can recognize several contemporary
diseases in fossils that predate human existence. Zhe-Xi
Luo recalls one of the museum’s meat-eating dinosaurs,
or therapods, whose skeleton showed evidence of gout.
(“They
drank port, too!” jokes Wible.)
The bones of certain
living creatures with prehistoric roots might even give
modern researchers clues for fighting
cancer, Olsen suggests. “They’ve never been
able to induce or diagnose cancer in sharks,” she
notes. “So, although in some ways they are more
primitive, their cartilage is thought to suppress the
development
of the arterial system of tumors.” Finding that
mechanism, she says, may yield data for human treatment.
And just as the evolutionary record shows the longevity
of disease, Olsen says it may also suggest natural remedies: “Look
at the thousands of years people have been using herbal
medicines and natural products to great advantage. Many
of these are far less destructive to the human cell than
chemotherapy or radiation. A lot more can be learned
about prevention by utilizing that knowledge.”
Lazo
agrees, noting that pharmacology has barely scratched
the natural surface. “More than 50 percent of drugs
come from natural products,” Lazo says. “The
best estimate is that we have looked in one percent of
nature for drugs—[not] the other 99 percent of
species. We know there are millions of possibilities,
but we have
not systematically evaluated them. That’s what
these folks do. They’re interested in organizing
how species are related.” (A Pitt team is currently
scanning 75,000 natural extracts from the National Cancer
Institute,
and Lazo reports that they have found several with potential
anti-cancer properties.)
The Evolution of Disease
The natural sciences also have much to teach us about disease-causing
pathogens, which often evolve even faster than we do.
Viruses quickly figure out how to outsmart antibiotics
by mutating. The same defensive ability allows them to
jump from one species to another. The 1918 flu pandemic,
which killed nearly 40 million people, began as a virus
native to wild birds—just like the avian flu that
worries epidemiologists today.
“
Why is it that SARS and all kinds of ugly influenzas are
always coming from
Asia to North America, and never vice versa?” Beard
asks. “Because Asia is a hotbed for biological diversity.
And it also happens to be a place where lots of people
are interacting with lots of different life forms on a
very personal level, so its flu viruses are more diverse
and more potentially virulent.”
Olsen has seen parallels
in early Asian cultures. “When
people start domesticating animals, they are much more
intimate with animals than ever before,” Olsen explains. “Certain
diseases can be easily transmitted through direct contact
with animals or their byproducts; and others can be transmitted
through wild animals, by exposure or ingestion.” She
uses as an example the practice of certain African cultures
eating chimpanzees, which are subject to deadly forms of
diseases that also affect humans. “That really sets
the stage for transmission.”
Even when it doesn’t
involve disease, diet affects the health of cultures. Olsen
offers another Asian analogy: “Among
Mongolian pastoralists, who depend heavily on dairy products,
it’s rare to find lactose intolerance. In China,
where people historically rarely consumed raw milk, it’s
the norm.”
One Big Family
Recent headlines on genetic findings have linked three
million Irishmen worldwide with one common ancestor,
and most Ashkanazi Jewish women trace just four matriarchs.
Meanwhile, comparing the complete human genome to animals
is allowing researchers to see more clearly how our species
is related to others, says Luo.
“
There are now six different species of mammals—human,
mouse, rat, dog, chimpanzee, and cow—whose genomic
maps have been completed,” Luo explains. “When
you see one expression of a gene in rodents, and you have
another similar correlating one in humans, you know these
genes are tied to the same kind of function. But think
about the larger picture: compare a rodent with a chimpanzee
and a human being. The fundamental concept is, we are tied
together with one gene-alogy. We have one family tree.”
Beard
adds that environmental health and global health, research
areas in which the University of Pittsburgh has
an international reputation, also can be enhanced by the
museum curators’ expertise in archaeological populations.“
Some global societies are still dealing with diseases
like leprosy, tuberculosis, or untreated syphilis,” Beard
says. “Sandi, in particular, will bring expertise
to bear on the health of past populations.”
“We can, and should, look at working conditions
and environmental conditions in prehistoric times,” Olsen
says. “Archaeologists employ the same
techniques as forensic scientists to determine how humans died. That’s
how we knew that one of the Bog People, a 16-year-old girl (from a
recent museum exhibition on the remains of ancient Europeans), had severe scoliosis
and walked
with a limp. We also know that Romans had pipes made of lead, a source of lead
poisoning. You can even tell from a skeleton if someone habitually rode a horse.”
John
Mahoney, M.D., assistant dean for medical education at Pitt medical school,
is excited about all that the new collaboration will mean to the students
and researchers. “It can broaden student horizons by showing them how
medicine is a piece of the broad domain of natural sciences, and how understanding
the natural sciences will enhance learning about medicine,” Mahoney
says. “And
I think this shows that we have an academic community that plays well together.”
Just
as Pitt researchers benefit from synergies with other Oakland neighbors,
like Carnegie Mellon, Mahoney foresees that they’ll also benefit
from the wealth of expertise offered by museum scientists. For their
part, the museum’s
scientific team is looking forward to working with Pitt’s cutting-edge
equipment such as scanning electron microscopes. “They have much
better facilities and the newest equipment for research, which they’ve
offered to share with us on joint projects,” says Olsen.
Beard
sees the ultimate product of the collaboration as being “reciprocal
illumination.”
He adds: “Our knowledge and insight will
illuminate biomedical issues, and the insight and expertise on the
Pitt medical school side will help us
address issues
we’re concerned with. That would be a perfect result.”
| THE EVOLUTION SCIENTISTS: |
 |
Chris Beard
Position: Curator and Head, Section
of Vertebrate Paleontology; joined staff in 1989
Education: Ph.D., Johns Hopkins University School of Medicine
Research Interests: Biogeography, primates, and the basis of evolution. “John
and Luo are interested in heads. I’m interested in limb
anatomy—arms and legs.”
Career Highlights: MacArthur Fellow, 2000-2005; award-winning author, The
Hunt
for the Dawn Monkey: Unearthing the Origins of Monkeys, Apes and Humans, 2005 |
Sandra
Olsen
Position: Curator of Anthropology; joined
staff in 1991
Education: Ph.D., University of London
Research Interests: Early horse domestication in
Central Asia,
c. 3500 B.C.; violence. “I use for-ensics
to identify kinds of wounds.
I also look at wounds in animals, whether they
were hunted with a stone projectile point or a
bone
projectile point.”
Career Highlights: Nine field
expeditions to Kazahkstan since 1993, funded by
National Science Foundation. Currently editing
Horses and Humans: The Evolution of the Equine
Human Relationship. Past research on skeletal remains
of Northern Plains Indians has promoted a continuing
study of anthropological violence
|
John Wible
Position: Curator and Head, Section of Mammals;
joined staff in 1998
Education: Ph.D., Duke University
Research
Interests: Skulls and teeth of early and living
mammals. “We
have a very broad-based
collection of all mammals. I have
an incredible collection that I can bring to
any number of topics.”
Career Highlights: collaborative research
(with Z.X. Luo and others) published in Science,
Nature, and other peer-reviewed journals; senior
editor of the museum’s scientific publication
series
|
Zhe-Xi Luo
Position: Associate Director of Research and Collections;
Curator, Section of Vertebrate Paleontology;
joined staff in 1996
Education: Ph.D., University of California at Berkeley
Research Interests: Origins of early mammals, origins
of mammalian skull growth (face and teeth). “All
human beings have only two generations of teeth.
It turns out the origin of this dental replacement
pattern can be documented from fossils that are
220-190 million years old.”
Career Highlights: Recipient of
National Science Foundation CAREER award; led the
team of museum
scientists that discovered a new 150-million-year-old
species of early mammal, dubbed "Popeye" because
of its massive forearms; adjunct faculty member
at the University of Pittsburgh |
|
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2006 CARNEGIE Magazine. All rights reserved.