2008年12月7日 星期日

Balls and brains


英研究:男性智商高 精子品質也較佳
【12/6 22:35】

〔中央社〕根據英國一項最新研究,智商高的男性不僅精子品質較佳,身體也較健康,高智商同時讓男性更有女人緣。

英國國王學院King’s College研究人員,對4462名曾在越戰服役的前美國士兵的智商測驗及健康檢查資料分析,其中425人並提供精子樣本。

研究人員再針對受訪者的智商、精子品質(包括精蟲數、精子活動力等 評 少每次射精之精子數)、年齡和生活習慣(使用身體質量指數body mass index、是否抽煙、喝酒、吸毒)等研究它們之間的關連性。

結果發現,智商較高的男性,精子的品質較佳,這個正相關性並非因為受訪者有較佳的生活習慣,如避免抽煙和飲酒。

負責這項研究的阿丹Rosalind Arden指出,研究也發現,高智商男性普遍較健康,主要是因為他們的基因所致,而非全因良好的生活習慣。

研究人員指出,如果夫婦有受孕困難,不能因此指責先生不夠聰明,或是試圖加強腦力,提高升格為父親的機率。

阿丹強調,我們不能就此下結論說,喜歡玩培樂多Play-Doh玩具的男性,精子品質就比愛看柏拉圖Plato的人差。研究結果支持理論上很重要的「健美因素fitness factor」觀念。 評這fitness是達爾文"適者生存"之觀念才對

她說,「健美因素」是影響許多包括智商等遺傳特質的重要因子,使部份人在孕育下一代時較其它人更成功。

這項研究結果刊登在「智商Intelligence」期刊。


Evolution

Balls and brains

Dec 4th 2008
From The Economist print edition

The quality of a man’s sperm depends on how intelligent he is, and vice versa


Illustration by Peter Schrank

THERE are few better ways of upsetting a certain sort of politically correct person than to suggest that intelligence (or, rather, the variation in intelligence between individuals) is under genetic control. That, however, is one implication of a paper about to be published in Intelligence by Rosalind Arden of King’s College, London, and her colleagues. Another is that brainy people are intrinsically healthier than those less intellectually endowed. And the third, a consequence of the second, is that intelligence is sexy. The most surprising thing of all, though, is that these results have emerged from an unrelated study of the quality of men’s sperm.

Ms Arden is one of a group of researchers looking into the connections between intelligence, genetics and health. General intelligence (the extent to which specific, measurable aspects of intelligence, such as linguistic facility, mathematical aptitude and spatial awareness, are correlated in a given individual) is measured by psychologists using a value called Spearman’s g. Recently, it has been discovered that an individual’s g value is correlated with many aspects of his health, up to and including his lifespan. One possible explanation for this is that intelligent people make better choices about how to conduct their lives. They may, for example, be less likely to smoke, more likely to eat healthy foods or to exercise, and so on.


Alternatively (or in addition) it may be that intelligence is one manifestation of an underlying, genetically based healthiness. That is a view held by many evolutionary biologists, and was propounded in its modern form by Geoffrey Miller of the University of New Mexico, who is one of Ms Arden’s co-authors (and, as it happens, her husband). These biologists believe intelligence, as manifested in things like artistic and musical ability, is such a reliable indicator of underlying genetic fitness that it has been chosen by members of the opposite sex over the millennia. In the ensuing arms race to show off and get a mate it has been exaggerated in the way that a peacock’s tail is. This process of sexual selection, Dr Miller and his followers believe, is the reason people have become so brainy.

Hitting the g spot

Ms Arden sought to test this idea in a way that excluded intelligent choice and got directly at any correlations between intelligence and health that operate at the physiological level. She chose sperm quality because it is both easily measured and about as far from intelligent choice as it is possible to imagine—and because the relevant data had already been collected.

Her retrospective “volunteers” were former American soldiers enrolled in what was known as the Vietnam Experience Study. In 1985 almost 4,500 veterans of that war volunteered for extensive medical and mental examinations. Some of them gave semen samples that were analysed for sperm concentration (ie, number of sperm per cubic centimetre), sperm count (ie, total number of sperm in the ejaculate) and sperm motility.

Ms Arden found 425 cases where samples had been collected and analysed from unvasectomised men who had managed to avoid spilling their seed during the collection process and had answered all the necessary questions for her to test her hypothesis, namely that their g values would correlate with all three measures of their sperm quality.

They did. Moreover, neither age nor any obvious confounding variable that might have been a consequence of intelligent decisions about health (obesity, smoking, drinking and drug use) had any effect on the result. Brainy men, it seems, do have better sperm.

By implication, therefore, they have fitter bodies over all, at least in the Darwinian sense of fitness, namely the ability to survive, to attract mates and to produce offspring. That is an important finding. Hitherto, biologists have tended to disaggregate the idea of fitness into a series of adaptations that are more or less independent of each other. This work adds to the idea of a general fitness factor, f, that is similar in concept to g—and of which g is one manifestation. To him that hath, in other words, shall be given. Unfortunately for the politically correct, Dr Miller’s hypothesis looks stronger by the day.

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