Asia, track down the Discover magazine devoted to sex. Amazingly enough, you've got it rig

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> Asia, track down the Discover magazine devoted to sex. Amazingly >enough, you've got it right (not that I mean it's amazing _you_ got it >right, but that this is the amazing conclusion -- "cheating" improves >the female's general-offspring-viability.) Letting one male father >all of her offspring means there's a greater likelihood that any >"bad" genes he possesses are present in all of that female's offspring; >mixing it up seems a superior strategy. I initially misposted a response to this point. What follows is a paraphrase of the review I was basing my response on. I have retrieved the article on human reproductive strategies as evidenced by analysis of sperm counts. I was referring to an article previewing two papers to be published in _Animal Behaviour_ by Mark Bellis and Robin Baker of Manchester University. They used a survey of 3600 women and 35 couples to analyse the biological business of bringing sperm in contact with egg. The participants collected all sperm shed by the male in condoms. The scientists were testing a theory known as sperm competition. Their findings shed new light on human reproductive behaviour and on the nature versus nurture question. Their major findings were: 1. Men prefer larger, plumper women; they shed roughly twice as many sperm with a large woman than with a small woman. 2. Female orgasms have a role in controlling fertilisation. They can draw sperm higher up the reproductive tract at the crucial time. Conversely, they can prevent it. 3. Men who have been separated from their partner for some time shed more sperm. It is suggested that this is a strategy to swamp the competing sperm of other males. 4. 3/4 of the women had double mated at least once in their lives; i.e. had copulated with a male while viable sperm from a second male was still in their body. 5. Male masturbation "freshens up" sperm, increasing its prospects of successful fertilisation. 6. Female masturbation can be used to prevent fertilisation or to select between the sperm of competing males. 7. In periods of infidelity females altered their orgasm patterns, almost invariably to favour her lover over her regular partner. The studies showed far lower sperm retention after copulation with the regular partner compared to copulation with other men. The sperm competition theory suggests that that males are balancing competition with other males against the cost of producing sperm. As a result, the amount of sperm shed varied widely and correlated with circumstances. If the risk of competition was low, then the count was low. Conversely, if they had been away from their partner for a significant amount of time, then the count was much higher; 500 million compared to 100-200 million. Fascinating research. It shows that many of the physical events surrounding sex and the strategies adopted by males and females have evolved to give them reproductive advantage. Looks like a win for nature over nurture. ------------------------------------ Pat Dooley paraphrasing a preview of a research paper

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