Wild Health: How Animals Keep Themselves Well and What We Can Learn from Them - Softcover

Engel, Cindy

Softcover

ISBN 10: 0618340688 ISBN 13: 9780618340682

Publisher: Houghton Mifflin, 2003

Synopsis

As Dr. Engel emphasizes in this "enticing, well-referenced, [and] entertaining book" (Science), we can learn a lot about human health by studying animal behavior in the wild. Indeed, some of the natural, holistic, and alternative human medicine being practiced today arose through the observation of wild animals. In this groundbreaking work, Dr. Engel points out fascinating parallels between animal and human medicine. She offers intriguing examples of how animals prevent and cure sickness and poisonings, heal open wounds, balance their diets, and regulate fertility. For instance,

*chimpanzees carefully eat bitter-tasting plant "medicines" that counter intestinal parasites *elephants roam miles to find the clay they ingest to counter dietary toxins *broken-legged chicks have been known to eat analgesic foods that alleviate pain.

By observing wild health we may discover (or rediscover) ways to benefit our own health. As Craig Stotlz of the Washington Post noted, this "highly readable assessment . . . triggers more outside-the-double-helix thoughts about human health than anything I've read recently."

About this title

About the Author

Cindy Engel has a Ph.D. in biology from the University of East Anglia, with a concentration on the relationship between physiology and behavior in animals. She has done research on the behavior and health of wild rabbits and jaguars and for twelve years has been a lecturer in environmental sciences at the Open University. She has published numerous scientific papers, particularly in the prestigious journal Animal Behaviour, and for the past eighteen months has worked as a script writer and science advisor for a series of wildlife documentaries being produced by National Geographic. In addition to her research into the medicinal practices of animals, she has studied holistic medicine for humans and is a Shiatsu practitioner. She has two children, lives on a farm in Suffolk, and is not quite forty.

Excerpt. © Reprinted by permission. All rights reserved.

Wild Health

How Animals Keep Themselves Will and What We Can Learn from ThemBy Cindy Engel

Mariner Books

Copyright © 2003 Cindy Engel
All right reserved.
ISBN: 0618340688
1
HEALTH IN THE WILD
The multitude of the sick shall not make us deny the existence of
health.
— Ralph Waldo Emerson, 1860

The herbalist Juliette de Baïracli Levy has spent much of her long
life observing the way animals keep themselves well in the wild. In
one of her many books she writes, "Everywhere in the woods one
observes the wild animals rearing their young in health and freedom
from sickness."1 But this view is considered naively romantic by
wildlife health experts. Although an animal may seem healthy on the
surface, it may harbor diseases and parasites that drain its
resources and can flare up should resistance falter momentarily.
Furthermore, the animals we see are the survivors, disease and death
having filtered out the less healthy. The wild animal, from this
perspective, fights a perennial battle with sickness and disease.
Which view is correct—the romantic vision of a healthy and
harmoniously balanced ecosystem, or the survivalist vision of a
ruthless, endless battle with death and disease? Paradoxically, the
two views are not as diametrically opposed as they might first
appear. When we see a beautiful swan glide across still water, the
movement appears effortless; the swan seems calm and untroubled, even
serene. An observer below the water, however, would see that the swan
is working hard: muscles are contracting and relaxing; legs and
webbed feet are pumping, pushing water aside with great effort. So it
is with wild health. While an animal may appear to glide effortlessly
through life"s troubled waters, a continuous struggle for survival
goes on, largely unseen. One perspective, then, is that behind a
façade of blissful, harmonious balance, each and every organism is
working to maintain its health and to survive. Another perspective is
that the struggle and selective survival actually create the
impression of harmony. I find no conflict in being able to see both
the struggle and the balance in the same vista, but evidently the
answer to the seemingly straightforward question "How healthy are
wild animals?" is influenced by the perspective of the observer.
Most of us gain our impressions of health in the wild
primarily from the news media—and news about wildlife, like news
about anything, is seldom good news. Currently, wildlife health makes
grim reading. Seal and dolphin populations in the Mediterranean and
Baltic seas, and in the coastal waters of the United States, have
been seriously affected by major disease outbreaks. It looks as if
the butylins used to protect the hulls of ships from barnacles and
such are the main culprits. These biocidal chemicals damage mammalian
immune systems, lowering resistance to disease and cancers.
Meanwhile, harbor porpoises in the English Channel and southern North
Sea are sickened by the high concentrations of polychlorinated
biphenols and mercury in their waters. And a global epidemic of
mysterious tumors affecting endangered sea turtles is linked to the
pollution of their watery breeding grounds.
On land, amphibians around the world are facing a health
crisis. Over the past two decades there has been a rapid decline in
their numbers, including extinction of some species, apparently
because of a global epidemic of a particular fungal infection.
Furthermore, the number of grossly abnormal amphibians born has
increased. Although the exact causes of this crisis are ambiguous,
environmental factors that disrupt both disease resistance and the
developmental systems of amphibians may play a role. All the main
contenders are caused by humans: global warming, agrochemicals, and
damage to the ozone layer.
Pollution distorts our impression of wild health, and the
occurrence of disease in wild-animal populations has become an
important indicator of ecological disruption. For a clearer picture
of how animals stay well, we need to assess the health of populations
far from the effects of industrial society. But even there our
presence can disrupt the survey. Early in the study of wild
chimpanzees at Gombe National Park in Tanzania, a polio outbreak
decimated the chimpanzees, killing four and leaving six permanently
disabled. It is thought that the virus spread from local humans, who
suffered a polio outbreak a month before, and was carried
inadvertently by vaccinated human scientists. The introduction of new
pathogens can be devastating for any population. The Spanish
conquistadors of the fifteenth and sixteenth centuries killed most of
the native Central Americans, not by superior warfare or cunning
intellect, but by bringing with them novel and consequently lethal
diseases (measles, for one). Today pathogens are traveling the world
with increasing ease as the international trade in food, plants, and
animals expands, and humans become increasingly mobile. As a result,
wildlife is exposed to many new diseases.
As the human population increases, the need for more and more
land for housing, agriculture, and tourism continues to squeeze
wildlife into ever-shrinking areas of natural habitat. Asian
elephants no longer have enough room to find the food and water they
need to stay well. Lions in the Serengeti National Park, along with
the last few viable populations of African wild dogs, have been
ravaged by canine distemper virus and rabies caught from domestic
dogs skirting the edge of the park. William Conway of the Wildlife
Conservation Society puts it succinctly: "Our growing herds and
flocks of domestic animals have become a plague to wildlife,
devastating habitat and spreading disease."
We hear far more about disease passed in the other direction—
from wild to domesticated animals. In Europe, wild badgers are blamed
by farmers for infecting domesticated cattle with tuberculosis, deer
are feared as carriers of foot-and-mouth disease because infected
herds can remain symptom free, and wild boar are hounded for
spreading classical swine fever (CSF) to commercial pigs because "CSF
has become milder in wild boar than pigs."3 In North America, free-
ranging bison are accused of spreading brucellosis to ranched cattle,
and wild deer of spreading tuberculosis to cattle. In what I consider
to be a totally illogical response, wild animals successfully keeping
disease at bay are often killed in order to protect sickly (but
profitable) domesticated livestock from infection. In the United
Kingdom, for example, a culling program is currently under way in
which twenty thousand badgers will be killed to prevent them from
possibly spreading tuberculosis to cattle.
This fear of wild animals as harbingers of disease is deeply
ingrained in the human psyche. The European hedgehog (small, spiny
heroine of a classic Beatrix Potter story) was recently described
as "among the most dangerous animals in Europe" by pathologist Ian
Keymer of London Zoo, who found that they carry at least sixteen
diseases known to affect people. And those "could be the tip of the
iceberg," he adds. "If we look closer we may find many more." Howard
Hughes would have understood, but if we follow this line of reasoning
to the extreme, we should never exchange air or body fluids with
other people, and we should certainly eradicate all other species on
earth—just to be safe!
Even though wild animals are able to carry diseases that
affect livestock and humans, it would seem sensible to explore why
they are so successful in fending off the worst effects of these
diseases, to look to them for ways of improving our own health and
that of our livestock, rather than trying to eradicate them. In
addition to looking at genetic resistance to disease, we would do
well to learn from the many behavioral self-help strategies that wild
animals employ.
One difficulty in assessing wild health is locating genuinely
wild places—where animals are not confined by perimeter fences,
culled, managed, or exposed to domestic animals or humans. Where is
the wild truly wild? Unfortunately, such habitats are shrinking
daily. A survey by the World Wide Fund for Nature found that more
than a third of the planet"s animal and plant species exist
exclusively on a scant 1.4 percent of its land surface.5 Moreover,
few places on earth remain uncontaminated by persistent pollutants
such as PCBs, dioxins, and DDT. With shrinking habitat and increasing
pollution, the opportunity to study undisturbed animal populations is
decreasing, while the need to do so becomes ever more urgent.
Even when we can find truly wild places, measuring or
assessing the health of animals living there is notoriously
difficult. Most of the evidence has tended to come from the
incidental comments of natural historians and scientists on the
health of animals being observed. In the early 1960s George Schaller,
of the New York Zoological Society, was the first person to study
wild lowland gorillas in West Africa. He found them healthy, lean,
well muscled with shiny coats, although he noted that they did catch
cold when the rains came. He was surprised to find roundworms in half
the fecal samples he examined because the gorillas were in such good
health. During the same time, Jane Goodall found wild chimpanzees to
be generally healthy, although they too quite often suffered from
colds and coughs during the rainy season. In the 1970s Cynthia Moss
started her long-term study of elephants in Amboseli National Park
and found them in extremely good health. (Things went wrong in later
years, though, when human encroachment and drought struck the herds.)
They had few diseases and only a few cases of unexplained sickness.
They rarely suffered from contagious epidemic diseases, such as
rinderpest, and were able to live to a ripe old age as long as they
could avoid drought and human hunters.
Schaller later went to Kanha, in India, where he found
disease rare among free-ranging, well-nourished chital (medium-sized
deer) and gaur (wild relatives of the cow). He concluded that the
health of domestic and wild hoofed animals is mainly a function of
the quality of the range, and that animals in poor condition as a
result of malnutrition become highly susceptible to parasites and
disease. Similar conclusions have been drawn by wildlife
veterinarians, who report that free-living marsupials in Australia
have few problems with infectious diseases, parasites, and cancers,
unless droughts, floods, or range restriction occur.
Unfortunately, anecdotal observations such as these are not
adequate to provide an accurate scientific picture of wild health.
Sick animals may alter their behavior in ways that make them harder
(or easier) to spot than healthy animals. Sick elephants, for
example, often separate from the herd to remain near water, shade,
and easy food, so an observer might underestimate the prevalence of
sickness. Hedgehogs, normally nocturnal, when sick will sit in the
sun during the day. A daytime observer might therefore think that
hedgehogs were more sickly than they are. More visible populations
can be taken as representing a species when this is not necessarily
so. Red foxes in the United Kingdom have moved into cities where food
is more plentiful and energy rich. These urban foxes live in
conditions much more crowded than their rural counterparts, because
the food supply is more concentrated. The health of the more visible
urban foxes is therefore not an accurate indication of the health of
wild foxes in their natural habitat.
Fortunately we are now seeing a minor flurry of health
assessments of wild animals living in some of the remotest parts of
the world, far from human settlements and pollution. In the 1990s the
Wildlife Conservation Society"s field veterinary program, headed by
William Karesh, ascertained that anacondas in Venezuela, macaws in
Peru, rock-hopper penguins and guanacos in Argentina, impala in
northern Namibia, forest duiker and pancake tortoises in Tanzania,
and African buffalo were all "in good physical condition." They were
muscled and lean, had cleanly healed serious wounds, were harboring
surprisingly few internal or external parasites, and showed no signs
of physical abnormalities such as those currently seen in amphibians.
Blood tests revealed that parrots had few infections with common bird
diseases and were successfully carrying avian viruses that commonly
wipe out captive parrots. Impala had surprisingly few previous
infections with local diseases, and duiker carried serious pathogens
such as leptospirosis with no visible ill effects. African buffalo
were outstanding in their ability to resist disease: "When buffalo
encounter viral and bacterial diseases, they generally suffer
little." They were in excellent health, yet blood tests revealed that
they had been in contact with leptospirosis, parainfluenza,
brucellosis, bovine herpes, bluetongue, and foot-and-mouth. As
successful combatants of such infections, they were
considered "carriers" of disease and much despised by local cattle
farmers.
These assessments tend to bear out the earlier observations
of Schaller, Goodall, and others that wild animals are often infected
with disease-causing organisms (pathogens) without showing any
symptoms. Repeatedly, animals appear to be in good condition when
blood and fecal tests show infection with pathogens or parasites. We
have to conclude that it is normal—natural—to be infected with low
levels of pathogens and parasites in the wild, but that somehow these
are kept below symptomatic levels. Benjamin Hart, a veterinary
research scientist at the University of California, Davis, concludes
that "wild animals generally are often immune to vector-borne
diseases and show few clinical signs of illness from parasite
infections."
Whether you consider such animals to be healthy or not
depends on whether you think the presence of the pathogen is the same
as the presence of the disease. In my view, it is not necessarily the
same: to carry pathogens without showing symptoms might be considered
a sign of extremely good health. Nor does it matter that these
animals are only the survivors—that the unhealthy ones simply failed
to make it. It is because they are survivors that they are of
interest to us. How is that they have survived and maintained their
health while others have not? They are not merely survivors; they are
doing very well. We should be interested in any behavior that has
contributed to this condition.
My unsurprising conclusion is that when wild animals are free
to range over undisturbed habitat, not exposed to high levels of
pollutants and not exposed to extremes of environmental change, they
are generally in good health. They live within an ecosystem to which
their physiology and behavior are, by virtue of their very survival,
well adapted. They have been exposed to local pathogens from an early
age, so that their immune system is primed (as it would be by
vaccinations) for resistance to them. They may get sick; but when
they do, the reason is primarily a strong disruption in their
environmental conditions (drought, pollution, lack of food,
overcrowding, or invasion by a novel pathogen).
Of course, the immune system plays an enormous role in
maintaining health, but it is by no means the only line of defense an
animal has—and it is certainly not independent of behavior.
Scientists at Stanford University captured healthy wild African green
monkeys and caged them separately to monitor the effects of stress on
their immune systems. The monkeys rapidly succumbed to infectious
diseases, and some even died despite being given all the nutrients
they were thought to need. This is not an isolated case. It is well
documented that healthy wild animals do not take readily to
captivity. Immune collapse is common. It is notoriously difficult to
maintain the health of wild-born gorillas in captivity even if the
animals were healthy when caught. White sharks cannot be held captive
at all; they die within weeks.12 The health of the immune system is
demonstrably interlocked with the animal"s behavior in its
environment.
Good health is therefore a balance between the opposing
survival instincts of the individual animal and all the other
organisms with which it shares its habitat. The ubiquitous nature of
pathogens means that constant attention is needed in order to remain
healthy. Animals cannot simply rely on their immune systems to keep
them well under constantly changing conditions. They must take an
active role in maintaining their own health. Incredibly, although the
physiology and immunology of disease are well researched, the
behavioral aspects of health maintenance have not received a great
deal of attention. (Benjamin Hart has published the only recent
reviews on this subject.)
Paradoxically, animal health research programs rarely study
health. Like human health research, animal health research
concentrates on sickness and disease rather than on how or why
certain individuals remain healthy in their natural surroundings.
Disease processes are usually studied in domesticated species and
under sterile laboratory conditions in which the animal is unable to
influence the course of the disease. In other words, the study
animals are observed passively enduring disease rather than actively
managing their own health. Until recently, scientists have not
focused on whether animals have any successful strategies for dealing
with disease.
To a layman the terms "health" and "fitness" may be
synonymous, but to a biologist they are very different. For
biologists, fitness is measured by the number of offspring an animal
has (that survive to reproduce themselves) compared to other
individuals in its population. An individual animal could, therefore,
be considered fitter than another if it successfully reared more
offspring—even if it was coughing up blood and dragging itself along
on paralyzed limbs! Of course, the fittest animal in a population is
often (although certainly not always) strong and healthy as well, but
the term "survival of the fittest" is frequently misused to refer to
strength or health. Even biologists pay little attention to health,
considering fitness a far more relevant attribute. However, the ways
animals maximize their health is clearly a pivotal mechanism by which
they increase fitness. Survival includes the important aspect of
quality. Merely surviving is not enough. A wild animal has to survive
in as healthy a condition as possible in order to compete
successfully with others and reproduce. If behaving in certain ways
enhances the health of certain individuals, it will give them an
adaptive advantage over others that do not behave in those ways.
There need be no conscious, deliberate, or intentional basis to these
behaviors.
What aspects of animal behavior are we looking for?
Basically, any action that quantitatively prevents or treats ill
health. There are several possible approaches. An important aspect of
all living organisms is that they manage to keep their insides in a
fairly steady state with respect to what is on the outside. It was
back in 1857 that the French physiologist Claude Bernard discovered
that organisms actively strive to maintain their internal state
within a narrow range. This phenomenon, called homeostasis, allows
the organism a degree of independence from exterior conditions. Many
homeostatic mechanisms are physiological: that is, they involve the
processes and functioning of the body. As external temperature
increases slightly, for example, a mammal might start to sweat; the
capillaries near the surface of its skin dilate so that the blood is
cooled near the outside of the body and internal temperature is
stabilized. But if these physiological changes do not successfully
rebalance body temperature, the animal may change its behavior by
seeking shade or lying in cool water.
With this vastly oversimplified example, it is easy to see
how physiology and behavior interact to keep the internal
state "balanced" and thereby maintain health. Many aspects of health
maintenance behavior can be described as homeostatic. Other behaviors
such as grooming, resting, or even fasting are best described as self-
maintenance. Some actions, though, are only taken in response to a
health disruption and are called (unsurprisingly) illness response
behaviors. Some involve the animal"s use of a substance not made by
itself, in such a way as to rectify malaise, and are therefore called
self-medication. Collectively, these health maintenance behaviors are
the focus of this book.

Copyright © 2002 by Cindy Engel. Reprinted by permission of Houghton
Mifflin Company



Continues...

Excerpted from Wild Healthby Cindy Engel Copyright © 2003 by Cindy Engel. Excerpted by permission.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.

Edition details

• Publisher: Houghton Mifflin
• Publication date: 2003
• Language: English
• ISBN 10: 0618340688
• ISBN 13: 9780618340682
• Binding: Paperback
• Number of pages: 288