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:

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 non-hierarchal 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/stress.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%20Acacus%20Cave%20paintings%203-756757.JPG

Consequences 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 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 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