Transcript Role of Resources and Disease in Shaping the Human Population

Role of Resources, Behavior and
Disease in Shaping the Human
Population
A Historical Perspective
Disease

Defects that cause
disease now might have
just been simple
variations.

May have been harmless
or useful but are harmful
now.
http://www.daviddarling.info/images/DNA.jpg
Disease
James Neel: In the ancient environment
humans needed a “thrifty gene.”
 In modern times however, in the Western
World, humans don’t require reserves of
glucose.
 Explanation for obesity and diabetes.

James V. Neel
Source: http://www.scielo.br/img/fbpe/gmb/v23n3/4349f1.jpg
Behavior

The behavior of our ancestors can also be a
factor in explaining the modern human populace.
Bipedalism


Resources forced our
ancestors to turn to
bipedalism.
Bipedalism causes some
problems:

Examples: Prenatal &
Birthing problems, back
aches, knee problems.
Source: http://www.crystalinks.com/lucypaleon2.jpg
Depression

Depression: social
technique dating back
to the ancient
environment.
http://www.drjoecarver.com/clients/49355/1053332_org.jpg
Theories about Depression

Various theories:

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Nesse: Depression a strategy to conserve
energy and resources.
Allen and Badcock: Signaled to dominant
individuals that the depressed individual was
not a threat and needed support.
Depression in the Modern World

In the modern world
depression may no longer
be useful because
humans live in a nonhierarchal environment
that is much more
isolated.
http://upload.wikimedia.org/wikipedia/commons/d/
db/NYC-Skyline-1.jpg
Stress


Stress may also have
been beneficial to
ancient humans,
explaining why it still
exists.
Stress prepares the
body to overcome a
threat and to then
recover from an
experience.
http://www.worksafesask.ca/files/ont_wsib/certmanual/stres
s.jpg
Stress in the Modern World

Stress, beneficial to our ancestors may
now be harmful to modern humans.


The body secretes adrenaline and cortisol
which mobilizes fatty acids and glucose.
Now this is not as necessary and can cause
much more harm by contributing to certain
disease.
Tool Making

Tools allowed our
ancestors to do a lot
of things they couldn’t
previously do:


Examples: scavenging
marrow from bones,
extracting termites.
This invention had
consequence that
have been extremely
helpful to the modern
human populace.
Adaptations necessary for tool-making

Needed to evolve mobile
thumb joints, powerful
muscles and large
fingertips.

These adaptations allow
humans to do things that
other animals and even
other primates cannot do.
http://www.southpalmorthopedics.com/
portals/2/MedicalLibraryAssets/Medical/
CMCArthroFINAL_small.jpg
Consquences



Humans could vary their
diet. Allowed the evolution
of a much larger brain,
which requires a great deal
of nutrients on a daily
basis.
Larger brain has benefits
such as the ability to
reason, the evolution of
language and so on.
Natural selection favored
those ancient humans with
the abilities to make tools.
http://www.h4ppy.com/blog/uploaded_images/Jebel%20Acac
us%20Cave%20paintings%203-756757.JPG
Consequences


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
A larger brain itself is
helpful to humans.
Debate as to how the brain
evolved to become so
large.
Bruce Lahn: As society
developed, the greater
cognitive abilities that a
large brain provided were
beneficial.
Larger brains could
manipulate the social
structure and their
environment.
http://psyweb.com/Brain/Bimages/BW_brain.jpg
Evolution of Language

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The ability to speak language for our ancestors
provided great advantages.
Communicate ideas, express your needs and
even convince others.
Group survival capabilities would be much higher
as well.
Noam Chomsky: Those who could use language
would be isolated from other groups, result a
“new language-based species.”
Evolution of larynx itself shows its importance.


Position of larynx makes humans susceptible to choking.
Variation would not be passed on to another generation,
unless a selective advantage such as language existed.
Sources
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Barbujani, Guido, and Laurent Excoffier. "The History and
Geography of Human Genetic Diversity." Evolution in Health and
Disease. Ed. Stephen Stearns. New York: Oxford UP, 1998. 27-40.
Feachem, Richard, and Oliver Sabot. "Surviving disease." Survival
: The Survival of the Human Race. Ed. Emily Shuckburgh. New
York: Cambridge UP, 2007. 99-122.
Nesse, Randolph M., and George C. Williams. "Research Designs."
Evolution in Health and Disease. Ed. Stephen Stearns. New York:
Oxford UP, 1998. 16-22.
Pollard, Tessa. Western Diseases: an Evolutionary Perspective.
New York: Cambridge UP, 2008.
Richards, Graham. Human Evolution : An Introduction for the
Behavioral Sciences. New York: Routledge, 1987.
Strassman, Beverly L., and Robin Dunbar. "Putting the Stone Age
in Perspective." Evolution in Health and Disease. Ed. Stephen
Stearns. New York: Oxford UP, 1998. 91-101