Boys may delay their sisters from becoming women and from having sex, new findings from Australia suggest.
The presence of older brothers seemed to delay the onset of menstruation of girls by nearly a year on average, and having younger brothers seemed to postpone the beginning of sexual activity in women by slightly more than a year, scientists found after interviewing 273 Australians.
To learn whether they also had an effect on their sisters' reproductive success, researchers investigated 197 women and 76 men. They ranged in age from 18 to 75, and all but 10 - seven of them women - had siblings.
“This research helps us to better understand how family dynamics influence development,” said researcher Fritha Milne, a behavioral ecologist at the University of Western Australia.
In attempting to explain the delayed starts of menstruation and sexual activity, the researchers ruled out factors such as socioeconomic class. Instead, they conjectured that older brothers may have delayed the physiological maturation of sisters by absorbing more parental resources or by applying psychological stresses. Meanwhile, younger brothers may have delayed girls' behavioral maturation by demanding that their older sisters assume care-taking roles.
據(jù)美國“趣味科學(xué)”網(wǎng)站8月17日?qǐng)?bào)道，男孩的存在可能會(huì)推遲自己姐妹變成女人以及發(fā)生性關(guān)系的時(shí)間，澳大利亞科學(xué)家的最新研究表明。
科學(xué)家在調(diào)查訪問了273名澳大利亞人后發(fā)現(xiàn)，哥哥的存在會(huì)讓女孩子們的月經(jīng)初潮平均晚來一年，而弟弟的存在則會(huì)使女孩初次發(fā)生性行為的時(shí)間推遲一年以上。
為了了解兄弟的存在是否會(huì)影響女孩子的生殖情況，研究人員調(diào)查訪問了197位女性和76位男性。他們年齡在18歲到75歲之間，除了10人沒有兄弟姐妹外(10人中有7位是女性)，其他人都不是獨(dú)生子女。
“該項(xiàng)研究有助于我們更好地理解家庭動(dòng)態(tài)如何影響生殖發(fā)育，”西澳大學(xué)行為生態(tài)學(xué)家弗利沙-米爾恩說道。
為了更好地解釋為何女孩初潮以及第一次性關(guān)系發(fā)生時(shí)間會(huì)因兄弟的存在而推遲，研究人員排除了某些因素如社會(huì)經(jīng)濟(jì)等級(jí)因素。相反地，他們推測兄長吸取了更多的父親元素且能夠施加心理壓力，故而使得女孩子月經(jīng)初潮推遲。而弟弟希望姐姐承擔(dān)起照顧自己的責(zé)任，從而延遲了女孩們行為的成熟。
