If a weak piglet positions itself next to a strong sibling while feeding, it may get some extra nutrition from inadvertently stimulated mammary glands. 

如果一个虚弱的小猪在喂食时呆着强壮兄弟身边，它可能会从不经意刺激的乳腺中得到额外营养。

撰文/播音：杰森·戈尔德曼(Jason G. Goldman)

翻译：郭鑫鹏

审校：丁可含

Human parents usually have one or sometimes two offspring at a time, and when babies get delivered we pour all out energy into child rearing. 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.

人类双亲通常只有一个或两个子女，当生下婴儿后，我们倾注我们全部的精力在抚养孩子上。但是其他动物在同一时间会抚养很多宝宝。相对虚弱的个体会处于很大的不利地位。如果没有足够的食物，例如，一只鸟妈妈可能会向那些看起来更有可能存活下去的小鸟提供更多食物。自然界是残酷的。

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 stimulate the mammary gland while they suckle, so they eventually starve from a lack of nutrition.

但是像猪一样的哺乳动物不会像鸟一样选择性养育他们的后代，因为所有的宝宝都在同一时间喂养。但是最强壮的小猪依然具有优势。一个假说指出弱小小猪在被喂奶时没有充足的能力去刺激乳腺，所以它们最后可能会因为营养缺失而挨饿。

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

但是结果发现对某个乳腺有力的刺激可以增加附近乳腺的血液流动。所以，如果一个弱小的个体精明地靠近一个强壮的兄弟，它可以比在其他位置得到更多的母乳。

“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.”

“我从对小猪的观察中得到这个推论，当然，因为我有一个感觉，弱小的个体可以在强壮兄弟的帮助下做得更好。”

Biologist Janko Skok from Slovenia’s University of Maribor.

马里博尔斯洛文尼亚大学生物学家扬科·斯科克。

To see if his hunch 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 differentiated the weaklings that survived from those that died.

为了验证他的直觉是否正确，斯科克观察了18窝幼崽，包括150个小猪。其中23个被归为弱小个体，这表明它们出生时体重低于1千克或者在断奶前死亡。然后他观察那些存活的弱小个体与死亡个体之间的区别。

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 implemented by their heavier siblings, who in turn do not suffer any cost from this activity.”

正如我们所料，那些存活的弱小个体更倾向于在它们强壮的兄弟姐妹身边接受喂养。“弱小个体由于不能很好地刺激乳腺，确实利用了它们强壮兄弟的强力刺激，相应的，其他强壮个体也不会因此受到什么损失。”

The research were published in the journal Behavioural Processes. [Janko Skok, Being a weakling and surviving: Keep the fittest siblings close-by when eating.]

研究发表在期刊《行为过程》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 result 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.

斯科克说猪饲养者通常会把小猪分入不同重量组中，所以一个猪妈妈喂养一群强壮的宝宝的同时，另一个猪妈妈喂养一群弱小的宝宝。但是以上结果表明，如果饲养者把不同体型的小猪混合，让弱小的小猪利用它们强壮同伴的优势，可以有更多的小猪存活。

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.

这项研究没有解释的是为什么我弟弟，在小的时候总是偷不到我的甜点，现在却比我还强壮。

-Jason G. Goldman