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Published byAndrew Reeves Modified over 8 years ago
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A New Media Presentation by Daniel Gettler
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In 1859, Charles Darwin published On the Origin of Species In this book, Darwin introduces the idea of natural selection, which has since been adopted and accepted by modern day biologists Natural selection is now seen as a staple of biology and essential for the evolution of a species
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Natural selection is: “A process that causes helpful traits (those that increase the chance of survival and reproduction) to become more common in a population and causes harmful traits to become more rare”
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An Apparent Paradox: Assuming that homosexuality is at least in part due to genetic factors (recent research suggests that it is), natural selection appears to fail at explaining homosexuality…
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A common misconception
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“There are numerous evolutionary mechanisms that might explain homosexual behavior, which are common in many species of animals”
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The 4 Main theories:
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1. It’s non-exclusive! Homosexuality exists on a continuum and homosexual behavior is often non-exclusive “Among animals, homosexual behavior is usually non-exclusive. For instance, in some populations of Japanese macaques, females prefer female sexual partners to male ones but still mate with males”— (they are bisexual)
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2. Indirect Benefit Some research suggests that homosexuality can be beneficial to relatives that carry some of the same genes Is are they ‘homosexual genes’ or just genes that influence how attracted a male OR female is attracted to men?
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**The researchers stressed that there is no single gene accounting for sexual orientation
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3. Kin Selection Indirect reproductive success through altruism towards kin Androphilia = sexual attraction to mature males This study is based on a group of homosexual males in Independent Somoa and despite the findings, we cannot conclude that the same
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4. Hormone Exposure in utero This theory is based on ‘gene expression’ Gene expression: “The appearance in a phenotype of a characteristic or effect attributed to a particular gene.”
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Things to keep in mind: There is more evidence for a genetic basis of male homosexuality than female homosexuality, which might suggest a different mechanism It is quite unclear how much of male or female homosexuality is due to genetics
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Animal studies do not allow researchers to draw accurate conclusions when studying sexuality; it is likely that homosexuality is common in different species for different reasons Humans are a unique social species The concepts of ‘homosexuality’ and ‘gender’ are socially constructed ideas that have only become ‘relevant’ in the past 1,000 years
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Conclusion Genetic sterility guarantees 100% infertility from the moment a person is born. Genetic sterility has not been selected against throughout evolution. Do you think homosexuality ever will be? Probably not! *Because this is such a sensitive subject, I have to stress that this project was created from an inquisitive evolutionary and genetic approach and is in no way criticizing homosexuality
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Works Cited http://www.newscientist.com/article/dn13674-evolution- myths-natural-selection-cannot-explain- homosexuality.html#.U1cPWeZdVWY http://www.newscientist.com/article/dn13674-evolution- myths-natural-selection-cannot-explain- homosexuality.html#.U1cPWeZdVWY http://www.ehbonline.org/article/S1090-5138(06)00069- 9/abstract http://www.ehbonline.org/article/S1090-5138(06)00069- 9/abstract http://en.wikipedia.org/wiki/Homosexual_behavior_in_ani mals http://en.wikipedia.org/wiki/Homosexual_behavior_in_ani mals http://en.wikipedia.org/wiki/Sexual_selection http://en.wikipedia.org/wiki/Sexual_selection http://en.wikipedia.org/wiki/Natural_selection http://en.wikipedia.org/wiki/Natural_selection
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