科学美国人60秒 SSS Adult Daughter Orcas May Trigger Moms' Menopause
时间：2018-12-24 作者：英语课 分类：2017年Scientific American(一)月
Menopause marks the end of a female’s babymaking era. And not just for humans. Female killer 1 whales go through menopause, too. And a new study finds that they might get pushed into menopause by their up-and-coming daughters. Those findings are floated in the journal Current Biology. [Darren P. Croft et al., Reproductive Conflict and the Evolution of Menopause in Killer Whales]
Female orcas usually quit popping out calves 2 between the ages of 30 and 40. Yet they can live to be more than 90 years old. One granny orca, who recently dropped from researchers’ radar 3 and is (sadly) presumed to have passed, was thought to be 105.
But why would a female whale stick around for so long after she’s done adding to the gene 4 pool? One theory is that it pays to keep nanna around so she can help care for the younger members of her family group. Indeed, matriarchal orcas do spend a lot of time nurturing 5 their descendants.
But that doesn’t explain why the old gals 6 should stop having babies of their own. To dive deeper into that issue, researchers examined 43 years’ worth of demographic data on two populations of killer whales in the Pacific Northwest. The records tracked the ages and genealogical relationships of the resident orcas, including 525 calves.
Turns out that when mothers and daughters breed at the same time, the calves of the elder females—for reasons yet unclear—are almost twice as likely to die by the age of 15 than those of the younger moms. Which the researchers say could account for why the grande dames 7 ultimately give up on reproduction and coast through their golden years doting 8 on the gargantuan 9 grandkids.
—Karen Hopkin
- Heart attacks have become Britain's No.1 killer disease.心脏病已成为英国的头号致命疾病。
- The bulk of the evidence points to him as her killer.大量证据证明是他杀死她的。
- a cow suckling her calves 给小牛吃奶的母牛
- The calves are grazed intensively during their first season. 小牛在生长的第一季里集中喂养。 来自《简明英汉词典》
- They are following the flight of an aircraft by radar.他们正在用雷达追踪一架飞机的飞行。
- Enemy ships were detected on the radar.敌舰的影像已显现在雷达上。
- A single gene may have many effects.单一基因可能具有很多种效应。
- The targeting of gene therapy has been paid close attention.其中基因治疗的靶向性是值得密切关注的问题之一。
- These delicate plants need careful nurturing. 这些幼嫩的植物需要精心培育。
- The modern conservatory is not an environment for nurturing plants. 这个现代化温室的环境不适合培育植物。
- Jim came skipping out at the gate with a tin pail, and singing Buffalo Gals. 这时，吉姆手里提着一个锡皮桶，嘴中唱着“布法罗的女娃们”蹦蹦跳跳地从大门口跑出来。 来自英汉文学 - 汤姆历险
- An' dey thinks dey wants mousy lil gals wid bird's tastes an' no sense at all. 他们想要的是耗子般的小姑娘，胃口小得像雀子，一点儿见识也没有。 来自飘（部分）
- Dames would not comment any further. Dames将不再更多的评论。 来自互联网
- Flowers, candy, jewelry, seemed the principal things in which the elegant dames were interested. 鲜花、糖果和珠宝看来是那些贵妇人的主要兴趣所在。 来自英汉文学 - 嘉莉妹妹
- His doting parents bought him his first racing bike at 13.宠爱他的父母在他13岁时就给他买了第一辆竞速自行车。
- The doting husband catered to his wife's every wish.这位宠爱妻子的丈夫总是高度满足太太的各项要求。
- My gargantuan,pristine machine was good for writing papers and playing solitaire,and that was all.我那庞大的、早期的计算机只适合写文章和玩纸牌游戏，就这些。
- Right away,I realized this was a mistake of gargantuan proportions.我立刻意识到这是一个巨大的错误。