Chapter Thirteen: The Study of Living Peoples - McGraw

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Chapter Thirteen: The Study
of Living Peoples
McGraw-Hill
© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved
The Study of Living Peoples
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How do we recognize evolutionary
changes in populations and identify
and study their causes?
What basic data do we gather in
order to describe human
populations?
What sorts of trends can we see in
populations within our species?
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In what ways have we humans adapted
to the varying environments in which we
live?
How have diseases influenced human
populations?
What are the results of our species’
evolution on the life histories-- the
“personal evolution”-- of the human
individual?
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Evolution within Populations
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Today we are able to characterize populations
and study their evolution at the most basic
genetic level of the individual letters (the four
bases) of the genetic code.
A variation in these letters is known as a single
nucleotide polymorphism. Because SNPs
reflect past mutations, we can use them to
estimate evolutionary relationships among
individuals and populations.
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definitions
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Single Nucleotide
Polymorphism (SNP)
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A single base pair of the genetic code that
displays variable expressions among
individuals.
Dermatoglyphics
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The study of the parallel ridges and furrows
on the fingers, palms, toes, and soles of the
feet.
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Describing Populations
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Populations are the units of
evolutionary change, and so the
nature of the groups we study cannot
be separated from the evolutionary
processes that affect those groups.
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What can we say from demographic
statistics about the human species in
general?
One thing is certain--our total population is
going to increase.
Since the beginning of farming and animal
domestication some 12,000 ya, the rate of
increase of the human population has
accelerated, jumping sharply with the
Industrial Revolution of the eighteenth
century.
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Definitions
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Demography
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The study of the size and makeup of
populations.
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Human Adaptations
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Humans have to deal with nearly every
imaginable set of environmental
circumstances the earth presents, and we
have been doing this for just about as long
as modern Homo sapiens has existed.
One would expect, therefore, that different
populations of our species would be
differently adapted to those various
environments.
Obviously, most of our adaptations are
cultural.
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Species Adaptations
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As member of the same species, all
humans certainly share many
adaptations to variable conditions.
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One important environmental variable is
temperature.
Similarly, we are all exposed to ultraviolet
radiation from the sun.
Humans are also exposed to varying
levels of oxygen.
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Variation in Adaptations
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Populations that inhabit hot climates
tend to be linear in build, and those in
cold areas tend to be stockier.
Populations closet to the equator have
darker skin, and those farther away
from the equator have lighter skin.
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Fig 13.1
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definitions
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Polymorphisms
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Melanocytes
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Variations in the genetic code within a
species.
Specialized skin cells that produce the
pigment melanin.
Melanin
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The pigment largely responsible for human
skin color.
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Are all Polymorphisms Adaptively
Important?
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The distribution of blood types in the ABO
system is a perfect example of a
polymorphism with no obvious relationship
to the environment.
There seem to be no rhyme or reason to how
the various frequencies of the phenotypes
are dispersed around the world.
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Fig 13.12
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definitions
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Antigens
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Substances, such as proteins, that
can trigger an immune response, for
example, the production of an
antibody.
Antibodies
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Proteins in the immune system that
react to foreign antigens.
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Disease and Human Populations
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We tend to think of diseases as
abnormalities, but diseases are as
much a part of life as any other aspect
of our biological world.
Since many diseases are caused by
other living organisms- viruses,
bacteria, and protozoa- and are carried
by other species, they are really
perfectly natural.
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Disease and Human Populations
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Disease-causing species have adapted
to the biology of their hosts, and the
hosts at least attempt to adapt to the
disease-causing species.
Diseases are thus excellent examples of
evolutionary processes.
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Fig 13.13
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definitions
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Epidemiological
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Pertaining to the study of disease outbreaks
and epidemics.
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Bioanthropology of Individuals
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Individuals don’t evolve, at least not in
the sense that we are using the term
here.
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And yet bioanthropologists are interested
in growth rates, developmental rates, and
the timing of important events in the lives
of individual members of our species.
Why is this information important to
bioanthropology?
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definitions
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Distance Curve
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A graph that compares some variable
at different points in time.
Velocity Curve
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A graph that compares the rate of
change in some variable at different
points in time.
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definitions
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Menarche
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Menopause
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A woman’s first menstrual period.
The end of a woman’s reproductive cycle.
Life History
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The study of the timing of life cycle events
such as fertility, growth, and death.
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Summary
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While a major focus of bioanthropology is on
the evolutionary history of the hominids, the
study of the current product of that
evolution-- modern Homo sapiens-- is also
important.
We study living populations of our species
from several different yet interrelated
approaches.
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Questions for further thought
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The AIDS epidemic (with over 25 million
deaths so far) could be compared to the
Black Death of the fourteenth century
(with an estimated 25 million deaths).
How do the two epidemics compare? In
what ways are they similar or different?
Do the effects of the plague of
fourteenth-century Europe give us any
indication of how the HIV/AIDS epidemic
might affect Africa or other regions
where its frequency is now on the rise?
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The population crisis is a
controversial topic.
 Do you think, as do some, that
overpopulation is a key problem
in the world today, precipitating
many other major problems?
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Or do you think that the world can
sustain the current population and
the even larger population hat will
surely inhabit the world in the
future?
If the latter, how will we deal with
such numbers of people in terms of
food, water, space, pollution, and
intercultural conflict?
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Chapter Thirteen: The Study of Living Peoples - McGraw

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