Transcript How Are Humans Adapting in the Face of Globalization?

Chapter 13
Human Adaptation
to a Changing World
Chapter Preview

How Have Humans Adapted
Biologically to Naturally Occurring
Environmental Stressors?

What Is Evolutionary Medicine?

How Are Humans Adapting in the
Face of Globalization?
How Have Humans
Adapted Biologically to
Naturally Occurring
Environmental Stressors?
The Ethics of Human
Biological Research
When examining seemingly biological phenomenon
such as disease, cultural factors must be
considered at every level—from how that
phenomenon is represented in each social group to
how biological research is conducted.
The Ethics of Human
Biological Research: The
Tuskegee Syphilis Study

This study denied medical
therapy to African American
men in order to study
supposed differences in the
disease in this population.

Public outcry about the study
led to regulations that protect
human subjects in biomedical
research.
Types of Human
Adaptation
Humans have biological mechanisms for adapting:

Genetic adaptation


Developmental adaptation


Described by Darwin’s theory of natural
selection.
Permanent phenotypic variation from
interaction between genes and the
environment during development.
Physiological adaptation

Short-term physiological change in response
to a specific environmental stimulus.
Human Growth Curve
Franz Boas defined the features of the human growth
curve. The graph on the left depicts distance, or the
amount of growth attained over time, while the graph on
the right shows the velocity, or rate of growth over time.
Human Growth Curve
Boas found that immigrant children
had different growth curves than their
genetically similar parents.
 This is an example of a secular trend
= a physical difference among related
people from distinct generations that
allows anthropologists to make
inferences about environmental
effects on growth and development.

Acclimatization
Long-term physiological adjustments
made in order to attain an equilibrium
with a specific environmental stimulus.
High Altitude Acclimatization
(above 5000 ft.)
• It takes between 2 weeks and 2 months for your body to
adapt to living at higher altitude. Most of it happens
without an individual even being aware of the changes.
• In children, lungs naturally grow larger to accommodate
the need for increased oxygen. At very high altitudes, this
results in a more "barrel chest" appearance.
• In adults, lungs may have difficulty in high altitudes with
low oxygen and air pressure so, the body produces
additional red blood cells to carry oxygen more efficiently
• You also require more water at higher altitudes.
High Altitude Acclimatization
(above 5000 ft.)
High Altitude
Acclimatization

Observing that Kenyan
runners have won most
of the major marathon
competitions over the
past several decades,
coaches have emulated
the Kenyan approach.

Adaptation to the hot, dry
yet mountainous region
leads to a long lean build
and increased oxygencarrying capacity.
Adaptation to Heat and Cold:
Bergmann’s Rule
From biology, it states that warm-blooded animals from colder
climates usually have larger body masses than the equivalent
animals from warmer climates.
Adaptation to Heat and Cold:
Allen’s Rule
Also from biology, it states that warm-blooded animals from
colder climates usually have shorter limbs than the equivalent
animals from warmer climates.
Human Biological
Diversity: For Class
Discussion


Why would the stocky body and short limbs characteristic of
populations adapted to the cold of the Arctic or high altitude, as in
this person from the Andean highlands of Peru (left)?
Why would a tall, thin body, as seen in the Maasai of Kenya (right),
be well adapted to the heat?
The Hunting Response

In extreme cold, the limbs need enough heat to
prevent frostbite, but giving up heat to the periphery
takes it away from the body core.

Humans balance this through the hunting response:



When exposed to cold blood vessels
constrict.
Initial alternations between the open (warm)
and shut (cold) and the temperature of the
skin range dramatically.
Oscillations become smaller and more rapid,
allowing a hunter to maintain manual
dexterity required for tying knots or sewing.
Physiological Adaptation
to Heat

The human body’s primary physiological
mechanism for coping with extreme heat is
sweating or perspiring.

Sweating is a process through which water
released from sweat glands gives up body
heat as the sweat evaporates.

Without replacing sweat through drinking
water, exposure to heat can be fatal.
What Is Evolutionary
Medicine?
Medical Anthropology

A specialization that brings theoretical
and applied approaches from cultural
and biological anthropology to the
study of human health and disease.

A medical system is a patterned set
of ideas and practices relating to
illness.
Disease and Illness
A disease is a specific pathology; a
physical or biological abnormality.
 An illness refers to the meanings and
elaborations given to a particular
physical state.
 The term endemic is used to describe
a disease that is widespread in a
population.

Visual Counterpoint: For
Class Discussion
Shamans and biomedical doctors both rely upon
manipulation of symbols to heal their patients. The
physician’s white coat is a symbol of medical knowledge
and authority that communicates to patients just as clearly
as does the shaman’s drum.
Visual Counterpoint: For
Class Discussion

Both shamans and medical doctors also make use of
restricted knowledge to help their patients.

Can you think of other ways in which cultural values and
customs interact with disease and medical systems?
Problems with
Modernization


Building the Aswan Dam
in Egypt was a vital part
of modernization for that
country.
Unfortunately, the dam
increased the rates of
schistosomiasis in the
Nile River by creating a
massive artificial lake
upstream from the dam
that provides the ideal
environment for water
snails.
Evolutionary Medicine

Evolutionary medicine uses the
principles of evolutionary theory to
contribute to human health.

Basic to this approach is framing
health issues in terms of the
relationship between biological
change and cultural change.
Symptoms of Disease as
Defense Mechanisms
Evolutionary medicine proposes that
many of the symptoms – fever,
vomiting, coughing, and diarrhea -that biomedicine treats are
themselves part of the body’s defense
mechanism against infections.
Battling Disease: Culture
vs. Evolution

North American medical
anthropologist Emily Martin
has shown that scientific
depictions of infectious
disease draw upon military
imagery common to the culture
of the United States.

An evolutionary perspective
suggests that the quick life
cycle of microorganisms
makes this “battle” a losing
proposition for humans.
Evolution and Infectious
Disease

Viruses, bacteria, fungi, and parasites all have very
short life cycles compared to humans.

When competing on an evolutionary level, they will
continue to pose new threats to health, because any
new genetic variants appearing through a random
mutation will become incorporated in the population’s
genome more quickly.

While antibiotics will kill many bacteria, increasingly
resistant strains of bacteria are becoming more
common.
Prions

A prion is a protein lacking any
genetic material that behaves as an
infectious particle.

Prions are a kind of protein that can
cause the reorganization and
destruction of other proteins and
result in neurodegenerative disease
as brain tissue and the nervous
system are destroyed.
Mad Cow Disease and
Prions

The beef supply of several countries in Europe and
North America became tainted by prions introduced
through the cultural practice of grinding up sheep
carcasses and adding them to the commercial feed of
beef cattle.

Through the wide distribution of tainted feed, prion
disease spread from sheep to cows and then to
humans who consumed tainted beef.

Today countries without confirmed mad cow disease
ban the importation of beef from neighboring countries
with documented prion disease.
Medical Pluralism
The presence of multiple medical
systems, each with its own practices
and beliefs in a society.
 Most individuals can reconcile
different medical systems.
 Medical pluralism may become
increasingly necessary in areas of
public health.

How Are Humans Adapting
in the Face of
Globalization?
Globalization and Human
Adaptation

The term globalization refers to the increasing
interconnectedness of humans to one another and to
the environment.

Understanding globalization is critical for
understanding human adaptation and disease.

By examining the political ecology of disease, we can
reveal its social causes, bringing us closer to finding
long-lasting cures.
Structural Violence

Physical and/or psychological harm
(including repression, environmental
destruction, poverty, hunger, illness, and
premature death) caused by exploitative
and unjust social, political, and economic
systems.

A Health disparity is a difference in the
health status between the wealthy elite and
the poor in stratified societies.
Economic Disparity

After a natural disaster
such as Hurricane
Katrina, the ability to
recover is determined by
the relative wealth and
resources available to the
community.

In the hard-hit Lower 9th
Ward of New Orleans, for
example, a year after
water levels rose to
above the rooflines of
houses, much of the
neighborhood is still in
disarray.
Human Population Growth
Since the industrial revolution, human population size has been
doubling at an alarming rate. The earth’s natural resources will
not be able to accommodate ever-increasing human population
if the rates of consumption seen in Western industrialized
nations, particularly the United States, persist.
Diet and Health
The definition of malnutrition includes under nutrition as well as
excess consumption of unhealthy foods. Obesity is common
among poor working-class people in industrialized countries.
Starvation is more common in poor countries or in those that
have been beset by years of political turmoil, as evident in this
emaciated North Korean child.
Decline in Sperm Counts
A documented decline
in human male sperm
counts worldwide may
be related to
widespread exposure
to hormone-disrupting
chemicals.
Health Education

These Gambian children
are spending their Saturday
in the school library to make
up skits and songs about
health issues that they will
take out into their local
community.

They are a part of a peer
health educator group, a
tradition that stretches
throughout The Gambia and
beyond.