当奶奶在身边的时候，年轻的虎鲸吃得更好，活得更久

It's hard to measure how much we benefit from the influence of a grandmother.

很难衡量我们从祖母的影响中获益多少。

Grandmothers have a wealth of wisdom and experience — and that translates into all kinds of valuable life lessons.

祖母们拥有丰富的智慧和经验，这些都转化为各种宝贵的人生经验。

When it comes to keeping the little ones safe, grandmother may indeed know best. (Photo: Tory Kallman/Shutterstock)

We're hardly the only species to value them. In fact, their generational influence may play a critical role in orca society.

我们并不是唯一珍视它们的物种。事实上，它们的世代影响可能在虎鲸社会中扮演着重要的角色。

A study published this week in the Proceedings of the National Academy of Sciences suggests the elder whales are a key factor in keeping their grandkids alive, especially when food is scarce.

本周发表在《美国国家科学院院刊》杂志上的一项研究表明，年长的鲸鱼是维持孙辈生存的关键因素，尤其是在食物匮乏的情况下。

The survival rates of those young whales improve even more dramatically if the grandmother has already gone through menopause.

如果祖母已经经历了更年期，那么这些小鲸鱼的存活率会有更显著的提高。

That's particularly surprising since menopause among most animal species is typically associated with the tail end of life. Not so, however, with humans and some whales — including orcas, which can live decades beyond menopause.

这尤其令人惊讶，因为大多数动物物种的更年期通常与生命的结束有关。然而，人类和一些鲸鱼，包括逆戟鲸，却不是这样。逆戟鲸可以在更年期后存活几十年。

Now, it seems that added longevity has an evolutionary purpose. Grandmother whales live long after they've stopped being able to produce their own offspring, and their continued presence ensures the children of their children grow up strong and healthy.

现在看来，延长寿命有一个进化的目的。祖母鲸在停止繁殖后代后仍能活很长时间，它们的继续存在确保了它们孩子的健康成长。

It's possible that grandmother orcas simply have more time to spare. (Photo: Leonardo Gonzalez/Shutterstock)

For their research, scientists analyzed decades of census data on orca populations around Washington state and British Columbia. Orca calf mortality, they noted, rose sharply in the years following the death of a post-menopausal grandmother. But calves that still lived with their grandmas enjoyed a much higher rate of survivability.

在他们的研究中，科学家分析了华盛顿州和不列颠哥伦比亚省附近虎鲸种群数十年的普查数据。他们注意到，在一位绝经后的祖母去世后的几年里，逆戟鲸的幼鲸死亡率急剧上升。但是那些仍然和奶奶住在一起的小牛存活率要高得多。

The researchers suspect post-menopausal grandmothers simply have more time to dote on the young ones, caring for them as a kind of nanny and making sure they have enough food to eat.

研究人员猜测，绝经后的祖母们只是有更多的时间来溺爱年轻的孩子，把她们当作保姆一样照顾，并确保她们有足够的食物吃。

"The study suggests that breeding grandmothers are not able to provide the same level of support as grandmothers who no longer breed," lead author Dan Franks, a biologist at the U.K.'s University of York tells Agence France-Presse. "This means that the evolution of menopause has increased a grandmother's capacity to help her grand-offspring."

研究报告的主要撰写人、英国生物学家丹•弗兰克斯说:“研究表明，生育能力强的祖母无法提供与不生育能力强的祖母同样的支持。约克大学的教授告诉法新社。“这意味着更年期的进化提高了祖母帮助孙辈的能力。”

Humans may recognize this phenomenon as the "grandmother effect": Women who retain their strength after the decline of fertility have traditionally helped their daughters care for the children.

人们可能把这种现象称为“祖母效应”:在生育能力下降后仍然保持体力的女性传统上帮助女儿照顾孩子。

"This is the first non-human example of the grandmother effect in a menopausal species," Franks adds.

弗兰克斯补充说:“这是首次在更年期物种中发现祖母效应。”

"It has also been shown in elephants, but they are able to reproduce until the end of their lives. We currently know of only five species that go through menopause: the others are short-finned pilot whales, narwhals and beluga."

“这在大象身上也有体现，但它们能够繁殖直到生命结束。目前我们只知道有五种动物进入更年期:其他的是短鳍领航鲸、独角鲸和白鲸。”

Now, how exactly does one know when a post-menopausal orca granny is spreading her life-affirming cheer to the rest of the pod?

现在，我们如何确切地知道一个绝经后的虎鲸奶奶是什么时候把她的生命肯定的欢呼传播到豆荚的其余部分?

The researchers looked at 378 individual whales known to have a maternal grandmother. In the cases where a grandmother had died within the previous two years, the mortality rate for a young whale jumped by 4.5 times.

研究人员观察了378头已知有外祖母的鲸鱼个体。在前两年祖母去世的案例中，年轻鲸鱼的死亡率上升了4.5倍。

And in times of food scarcity, the "grandmother effect" was particularly pronounced.

在粮食短缺时期，“祖母效应”尤为明显。

"We have previously shown that post-reproductive grandmothers lead the group around foraging grounds, and that they are important in doing that in times of need, when the salmon are scarce," Franks explains to AFP.

弗兰克斯向法新社解释说:“我们之前的研究表明，繁殖后的祖母会带领这群鲑鱼四处觅食，而且在鲑鱼稀少的时候，她们在这方面很重要。”

"They are also known to directly share food with younger relatives. We also suspect babysitting."

他们还会直接与年轻的亲戚分享食物。我们还怀疑他们是保姆。”