AEAS阅读训练 – Hyena Society Stability Has Last Laugh

Hyena Society Stability Has Last Laugh 

Turns out that for hyenas, it’s not what you know, but who you know.

Spotted hyenas live in large, mixed-sex clans, with fairly stable social hierarchies—and the females are in charge.

“The matrilineal hierarchies that we see in spotted hyenas are also found in a lot of Old World monkeys.”

Michigan State University biologist Eli Strauss.

“It’s been perplexing for a long time to a number of people: what forces maintain this system? Because it is somewhat unusual in the animal kingdom.”

In some kinds of animal societies, your place in the dominance hierarchy can be explained by physical attributes, like body size. But in other animals, dominance rank can be acquired through things like age or nepotism.

Strauss and colleagues collected data about five generations of four groups of wild spotted hyenas in Kenya that they observed over a 27-year period. And the researchers saw multiple instances in which a smaller hyena came to dominate a larger one. They’ve even seen severely wounded hyenas become dominant to healthy ones. The results are in the journal Proceedings of the National Academy of Sciences.

Given those examples, it would seem that rank in spotted hyenas is fairly arbitrary. But it turns out that what researchers call “rank reversals” happen only rarely in this species: just fourteen percent of the time. So how does it stay so stable over time?

“They’re systematically related to the coalitionary support that we observed…So females who had stronger coalitions with their top allies were more likely to increase their social rank.”

Spotted hyenas could only climb the social ladder if they were able to maintain a strong alliance.

“The social bonds of these animals are really very fundamental in establishing the structure of their societies

In other words, the strength its relationships is what puts one hyena in its group’s spotlight.

土狼社会等级

事实证明,对于土狼来说,重要的不是你知道什么,而是你认识谁。

斑点鬣狗(土狼的一种)生活在一个大型的混合性别的氏族中,拥有相当稳定的社会等级,而且由雌性负责。

“我们在斑点鬣狗身上看到的母系等级制度,在许多东半球的猴子身上也发现了此种等级。”

密歇根州立大学生物学家Eli Strauss说道.

“长期以来,很多人都感到困惑:是什么力量维持了这个体系?因为这在动物界有些不寻常。”

在某些动物社会中,你在统治阶层中的地位可以用身体特征来解释,比如体型。但在其他动物中,统治地位可以通过年龄或裙带关系获得。

Strauss和他的同事收集了肯尼亚四组野生斑点鬣狗的五代数据,他们观察了27年。研究人员还发现了许多小鬣狗主导大鬣狗的例子。他们甚至看到严重受伤的土狼成为健康土狼的主宰。研究结果发表在《美国国家科学院院刊》上。

考虑到这些例子,斑点鬣狗的排名似乎是相当随意的。但事实证明,研究人员所说的“等级颠倒”在这个物种中很少发生:只有14%的几率。它是如何保持稳定的呢?

“它们与我们观察到的联盟支持有系统的联系……因此,与高层盟友有更强联盟的女性更有可能提升自己的社会地位。”

斑点鬣狗只有在能够维持强大的联盟关系的情况下才能爬上社会的阶梯。

这些动物的社会关系对于建立它们的社会结构是非常重要的

换句话说,正是这种强大的关系让一只土狼成为了团队的焦点。