Human Sexuality NOTES

Human Sexuality NOTES - Human Sexuality 07/01/2008 15:02:00...

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Unformatted text preview: Human Sexuality 07/01/2008 15:02:00 January 7, 2008 Why do people have sex? Evolution and sex The evolution of Sex Nothing in biology makes sense except in the light of evolution Why does anything have sex? The two fold cost of sex (the cost of males) New Mexico whiptails: an all female species of parthenogenetic lizards There is a cost of sexual reproduction Males cant give birth so when they are born they are only as good as their sperm. Parthenogenetic reproduction goes twice as fast because everyone can bear offspring. What are the benefits of sex? 1. Recombination of genes o Getting rid of harmful mutations. Getting rid of the mistakes. o In parthenogenetic reproduction there is degredation of the genome. There is no way to get rid of the harmful mutations so MULLERs RATCHET. The clones keep the harmful mutations and potentially gain more! o Think a photocopy of a photocopy of a photocopy etc 2. Producing genetic variety to elude parasites o Viruses, bacteria, worms, etc. that have been a main foe to evolution. o In 1970 a single genotype of hybrid corn was planted throughout the southeastern US. Along came a new strain of southern corn blight. Because of the uniform genome of the corn, most of the corn crop in the southeast was destroyed! Some individuals in a host population must have GENES for RESISTANCE if the host population is to survive. Genetic diversity is good! Monoculture is risky! o Why are parasites and diseases so effective at overcoming host resistance? Parasites can evolve ways to overcome resistance faster than hosts can evolve new types of resistance. o Sexual reproduction and the Red Queen hypothesis (Alice in Wonderland) Genetic recombination allows for genetic diversity among offspring which helps hosts keep up with parasites. Evolution Genetic variety o In order for the species to evolve there has to be variety and different codes. Some varieties are better than others Best varieties survive and prosper Adaptation Adaptations are solutions to evolutionary problems ie. Human eye Emotions are adaptations to evolutionary problems. Types of Natural Selection Survival/Mortality Selection Sexual Selection Kin Selection The Evolution of Maternal Care Pick the winning gene!...
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This note was uploaded on 04/17/2008 for the course PSYCH 320 taught by Professor Bailey during the Fall '08 term at Northwestern.

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Human Sexuality NOTES - Human Sexuality 07/01/2008 15:02:00...

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