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Human parents usually have one or sometimes two offspring at a time, and when babies get delivered we pour all our energy into childrearing. But other animals raise lots of babies at once. And the weaker individuals can be at a big disadvantage. If there's not enough food, for example, a mother bird might offer more to those chicks who are more likely to survive. Nature's a rough place.

人类的父母通常有一个或两个后代，当孩子出生后，我们将所有精力投入到养育孩子中去。但是其他动物会同时养育很多后代，而弱一点的后代则处于生长劣势中。例如，如果没有足够的食物，一只母鸟可能会提供更多食物给那些需要生存下来的小鸟。大自然是一个艰难生活的地方。

But mammals like pigs can't selectively provision their offspring the way birds do, because all the babies nurse at the same time. And yet the strongest piglets still seem to have an edge. One hypothesis goes that the weaklings might not have sufficient energy to stimulate¹ the mammary gland² while they suckle, so they eventually starve from a lack of nutrition.

但是，像猪这样的哺乳动物不能像鸟那样选择自己的后代，因为所有的猪崽都要同时看护养育。然而，最强壮的小猪似乎仍然有优势。一种假说认为，弱猪崽可能没有足够的能量得到哺乳，所以他们最终会缺乏营养。

But it turns out that vigorous stimulation³ of one mammary gland can increase blood flow in neighboring glands⁴. So if a weakling was canny⁵ enough to position himself next to one of his strongest siblings⁶, he might get more milk than positioned elsewhere.

但事实证明，强烈刺激乳腺会增加邻近腺体的血流量。所以如果弱崽足够精明找到位于壮崽旁边的位置，他可能会得到更多的奶。

"I got this idea during observations of piglets, of course, because I had a feeling that weaklings are doing better in the company of [the] strongest siblings."Biologist Janko Skok from Slovenia's University of Maribor.

“我在观察小猪时有了这个想法，当然，因为我有一种感觉，弱崽与最强壮猪崽为伴时会更好。” 斯洛文尼亚马里博尔大学生物学家Janko Skok说。

To see if his hunch⁷ was right, Skok observed 18 litters, including 150 piglets. Twenty-three of them were classified as weaklings, which meant they weighed less than one kilogram at birth or they died before weaning. Then he looked to see what differentiated⁸ the weaklings that survived from those that died.

为了验证自己的预感是否正确，Skok观察了18窝仔猪其中包括150头小猪，有23头被归类为弱崽，这意味着它们出生时的重量小于一公斤或他们会在断奶前死亡。然后他检验了那些存活下来的弱崽有什么不同之处。

And indeed, those weaklings that survived were more likely to nurse next to their strongest brothers and sisters. "Weaklings, which are limited in terms of mammary gland stimulation, actually take advantage of strong stimulation implemented⁹ by their heavier siblings, who in turn do not suffer any costs from this activity." The research were published in the journal Behavioural Processes.

事实上，那些存活下来的弱崽更容易呵护他们旁边的最强壮的猪崽。“弱崽刺激乳腺分泌的条件有限，竟能占到强壮猪崽刺激乳腺分泌乳汁的便宜，这些强壮猪崽也不会损失什么。”研究结果发表在《行为过程》杂志上。

Skok says that pig breeders commonly sort piglets into different weight classes, so the heaviest babies nurse together with one mother while a different mother raises the weaker babies. But his results might mean that more piglets could survive if breeders instead mixed piglets of different sizes, so that the smaller ones could take advantage of their larger counterparts.

Skok说，养猪人一般会根据仔猪分成不同的级别，所以强壮崽由母猪喂养的同时，也会分配不同的母猪喂养弱崽。但他的研究结果可能意味着，如果饲养者选择不同规模的仔猪，那么更多小猪可以存活下来，这样较小的仔猪就可以利用大猪崽而存活下来。

What this finding does not explain is why my younger brother, who as a kid always and failed to steal my dessert, is now stronger than I am.

这一发现并不能解释的是，为什么总是偷不到我的甜点的小弟弟，现在却比我强壮。