Big Brother Effect - The big brother effect 29 March 2003...

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Enlarge image 1 more image LITTLE brothers owe a lot to their older male siblings. Historically, the eldest have been saddled with the ageing family farm - not to mention the ageing family - leaving younger boys free to pursue serious commerce or adventure. Even today, younger brothers enjoy expert skateboarding instruction, tips on how to use the family car undetected and more generous curfews. Long before the younger ones appear, older boys have broken their parents in, making life less miserable for those who come after. But can boys really also credit their older brothers with determining their sexual orientation? The debate about whether homosexual men are born or made is hotly contested. Puritans still insist that homosexuality is a "lifestyle choice" (and a wrong one at that). Many gay men will tell you they have been sexually attracted to other men since they first noticed the difference between the sexes. Meanwhile, biologists have been fascinated by the question, not least because the observation that 2 per cent of men are attracted to members of their own sex contradicts everything that Darwin would have us believe. Science is not threatening to resolve this particular debate any time soon. But the idea that sexual orientation is fixed before birth has been strengthened with the intriguing finding that the more male babies a woman has borne, the greater the likelihood that any subsequent sons will be homosexual. Over the decades, scientists have found evidence to support both sides of the nature versus nurture argument (New Scientist, 28 September 1996, p 32 , and 28 November 1992 , supplement). Twin studies suggest that homosexuality isn't all down to the genes, but they also show that there must be a genetic component, as many more identical twins than fraternal twins share sexual orientation. In 1993, Dean Hamer at the National Institutes of Health in Bethesda, Maryland, even claimed to have found a region on the X chromosome where a male gay gene might reside. Several researchers have pointed to anatomical differences between gay and straight men. In 1991, Simon LeVay, then at the Salk Institute in San Diego, California, published evidence that a part of the brain known to vary in size between men and women was unusually small in homosexual men. In fact, in his post-mortem study, LeVay found that the region, known as the third interstitial nucleus of the anterior hypothalamus, or INAH3, was almost identical in size in women and gay men. LeVay argued it was evidence that gay men are born, not made. "It's much more than lifestyle or family processes," he insists. For years, LeVay's findings went unreplicated. Then, at last year's meeting of the Society for Neuroscience in Orlando, Florida, Charles Roselli at the Oregon Health and Science University in Portland presented supporting evidence from work in animals. He and his colleagues studied 27 sheep - 10 ewes, 8 normal rams and 9 rams that exhibited homosexual behaviour. In nature, about 8
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This note was uploaded on 10/14/2010 for the course ZOO 4125 taught by Professor Flanigan during the Fall '10 term at Univeristy of Wyoming- Laramie.

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Big Brother Effect - The big brother effect 29 March 2003...

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