Tenants who don't pay the rent are a bane of landlords everywhere.
不付房租的房客让世界各地的房东头疼。
And landlords who use heavy tactics to enforce payment are similarly a bane of tenants.
而使用高压手段强制要求付款的房东同样让租户痛苦。
Nor are these problems confined to human beings.
这些问题并不局限于人类。
Property-owning cichlid fish seem as ruthless about receiving what they are owed
和19世纪纽约下东区任何廉租房业主一样，
as any 19th-century tenement holder in the Lower East Side of New York.
拥有房产的鲷鱼似乎也会为了得到应得的东西而变得冷酷。
The fish in question, Neolamprologus pulcher, inhabit Lake Tanganyika in east Africa.
这种名为美新亮丽鲷的鱼生活在东非的坦噶尼喀湖。
They are co-operative breeders, meaning that dominant individuals do the breeding and subordinates assist in various ways,
它们是合作繁殖者，也就是说，占优势的个体负责繁殖，而从属的个体则以各种方式提供帮助，
in exchange for immediate survival-enhancing benefits that may lead to the ultimate prize of becoming dominant themselves.
作为交换，它们可以立即获得提高生存能力的好处，而这些好处最终可能导致它们成为支配者。
In the case of N. pulcher the main benefit is having somewhere to live.
对于美新亮丽鲷而言，主要的好处就是拥有居住地。
Dwellings, in the form of shelters dug out from sand under rocks, are controlled by dominant pairs.
在岩石下用沙子挖出的庇护所形式的住所，是由支配者控制的。
These dominants permit subordinates to share their accommodation,
这些支配者允许从属分享它们的住处，
and those subordinates pay for the privilege by keeping the property in good repair
这些从属通过保持财产的良好维修和保护支配者的鱼卵
and defending the dominants' eggs and fry against predators.
和鱼苗免受捕食者的侵害来支付自己所能享有的特权。
Though co-operative breeding by vertebrates has evolved several times
尽管脊椎动物的合作繁殖已经进化了好几次
(famous examples include the meerkat mongooses of southern Africa and the scrub jays of Florida),
（著名的例子包括非洲南部的猫鼬猫鼬和佛罗里达的灌丛鸦），
the question of how rental payments are enforced has never been definitively settled.
但如何执行租金支付的问题从未得到最终解决。
The presumption is that dominants punish subordinate defaulters.
有种假设是支配者会惩罚下级违反者。
But it is hard to prove, by observing wild animals, that this is what is happening.
但是通过观察野生动物，很难证明这种假设。

What was needed to clear the point up was an experiment. And fish are easier to experiment on than mongooses or jays.

需要进行一次实验来弄清楚这一点。与猫鼬或松鸦相比，用鱼做实验更容易。
Jan Naef and Michael Taborsky of the University of Bern, in Switzerland,
瑞士伯恩大学的Jan Naef 和Michael Taborsky因此捕获了
therefore acquired 96 specimens of N. pulcher and created menages of a pair of dominant landlords
96个美新亮丽鲷试样，并在沙底水族馆创造了支配者房东
and a subordinate tenant in sand-bottomed aquaria.
和从属租客的模式。
Left alone, the fish behaved much as they would have done in the wild,
如果不去管它，这些鱼的行为和它们在野外的行为差不多，
with the tenant doing the grunt work of maintaining the hollows in the sand, and good relations pertaining between all.
而租客则干着维护沙坑的粗活，它们之间的关系也很好。
However, if a tenant was prevented for a time from fulfilling its duties,
但如果一名租客被困在插入鱼缸的隔板后面，
by trapping it behind a partition inserted into the aquarium for that purpose, things changed.
并且在一段时间内无法履行其职责，那么情况就会发生变化。
When the partition was removed, the landlords attacked it,
当隔离墙被拆除后，房东们就开始攻击它，
and it showed a big increase in submissive behaviour for several minutes before things returned to normal.
并且在事情恢复正常之前的几分钟内，它的服从行为会大幅增加。
Whether similar treatment would be meted out for a failure to defend the landlords' eggs has yet to be determined.
如果租户们没能保护好房东们的卵，房东们是否会采取类似的措施还有待确定。
When prevented by a partition from driving away predators,
当由于被隔离而无法赶走捕食者时，
tenants were not subsequently on the receiving end of aggression from landlords—
租客就不会受到房东的攻击—
but since there were no eggs to defend at the time, that may not have been part of the contract.
由于实验中没有需要保护的卵子，所以保护卵子不在合约当中。
The predators in question, a species called Telmatochromis vittatus,
上述提到的捕食者是一个被称为饰圈沼丽鱼的鱼种，
are not a threat to adult specimens of N. pulcher, only to eggs and fry.
对美新亮丽鲷试样没有威胁，只对卵和鱼苗有威胁。
It is nevertheless clear from Dr Naef's and Dr Taborsky's experiment that, for cichlids at least,
但从Naef博士和Taborsky博士的实验中，我们可以清楚地看到，至少对于美新亮丽鲷来说，
the rent must be paid in a timely fashion, or punishment will be faced.
房租必须及时交纳，否则就要受到处罚。

来源：经济学人