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Evolutionary Impact of Resources, Behavior, and Disease on Human Population

Explore the historical perspective of how resources, behavior, and disease have shaped the human population. Discuss the impact of diseases, adaptations, tool-making, and the evolution of language.

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Evolutionary Impact of Resources, Behavior, and Disease on Human Population

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  1. Role of Resources, Behavior and Disease in Shaping the Human Population A Historical Perspective

  2. 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

  3. 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.

  4. James V. Neel Source: http://www.scielo.br/img/fbpe/gmb/v23n3/4349f1.jpg

  5. Behavior • The behavior of our ancestors can also be a factor in explaining the modern human populace.

  6. 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

  7. Depression • Depression: social technique dating back to the ancient environment. http://www.drjoecarver.com/clients/49355/1053332_org.jpg

  8. 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.

  9. 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

  10. 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

  11. 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.

  12. 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.

  13. 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

  14. 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

  15. 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

  16. 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.

  17. 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

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