这些鸟证明了你不需要一个大脑袋来适应复杂的社交生活

这些鸟证明了你不需要一个大脑袋来适应复杂的社交生活

Birds can form complex, multilevel societies, a new study finds, a feat previously known only in humans and certain other big-brained mammals, including some of our fellow primates as well as elephants, dolphins and giraffes.

一项新的研究发现，鸟类可以形成复杂的、多层次的社会，这是一项以前只在人类和某些其它脑容量大的哺乳动物身上才知道的壮举，包括我们的一些灵长类同胞，以及大象、海豚和长颈鹿。

Vulturine guineafowl may be the first non-mammal species known to create multilevel societies. (Photo: Martin Mecnarowski/Shutterstock)

It's also further evidence that birds — despite their relatively small brains — are much smarter and more sophisticated than we tend to assume.

这也进一步证明，尽管鸟类的大脑相对较小，但它们比我们通常认为的更聪明、更复杂。

Leveling up

升级

A group of vulturine guineafowl trots through Tsavo East National Park in Kenya. (Photo: Marius Dobilas/Shutterstock)

The subjects of this study are vulturine guineafowl, a heavy-bodied, ground-feeding species native to scrublands and grasslands in northeast Africa. These birds are an impressive sight, with a vivid blue breast and long, glossy neck feathers leading up to a bare, "vulturine" head with intense red eyes. And now, as researchers report in the journal Current Biology, we know they live in impressive societies, too.

这项研究的对象是秃鹫几内亚猫头鹰，一种身体沉重的地面食性物种，原产于非洲东北部的灌木丛和草原。这些鸟是一个令人印象深刻的景象，有一个生动的蓝色胸部和长有光泽的颈部羽毛，导致一个裸露的“秃鹰”的头与强烈的红色眼睛。现在，正如研究人员在《当代生物学》杂志上报告的那样，我们知道它们也生活在令人印象深刻的社会中。

Living in a multilevel society can offer big benefits, with different levels of the society serving specific adaptive purposes that evolved in response to different cost-benefit trade-offs. This includes reproduction and social support at the lowest tier, for instance, as well as perks like cooperative hunting and defense at higher tiers.

生活在一个多层次的社会可以提供巨大的利益，社会的不同层次服务于特定的适应性目的，以适应不同的成本效益权衡。这包括最低层级的繁殖和社会支持，以及更高层级的合作狩猎和防御等额外福利。

Birds of a feather

物以类聚

A social group of vulturine guineafowl may include several breeding pairs along with other birds. (Photo: Martin Mecnarowski/Shutterstock)

In the new study, however, researchers reveal vulturine guineafowl to be a "striking exception," according to a statement from the Max Planck Institute of Animal Behavior. The birds organize themselves into highly cohesive social groups, the study's authors report, but without the "signature intergroup aggression" common among other birds that live in groups. And they achieve this with a relatively small brain, which is reportedly small even by avian standards.

然而，根据马克斯·普朗克动物行为研究所的一份声明，在这项新研究中，研究人员发现，秃鹰豚鼠是一个“引人注目的例外”。该研究的作者报告说，这些鸟把自己组织成高度团结的社会群体，但没有群居鸟类中常见的“典型的群体间攻击”。他们用一个相对较小的大脑实现了这一点，据报道，即使以鸟类的标准来衡量，大脑也很小。

The results showed groups of vulturine guineafowl were associating with each other based on preference, the researchers say, as opposed to random encounters. The study also found that intergroup associations were more likely during specific seasons and around specific locations in the landscape.

研究人员说，结果显示，不同群体的秃鹰豚鼠会根据喜好而相互联系，而不是随机相遇。研究还发现，群体间的联系更有可能发生在特定的季节和景观的特定地点。

Secret society

秘密社团

The discovery of a multilevel society in vulturine guineafowl suggests this form of social organization might be more common than we thought, researchers say. (Photo: Sumeet Moghe [CC BY-SA 4.0]/Wikimedia Commons)

We already know birds aren't as simple as their brain sizes might suggest. Not only do many birds perform impressive cognitive feats — like using or even making tools — that seem too advanced for them, but research suggests many birds have significantly more neurons packed into their brains than do mammalian or even primate brains of the same mass.

我们已经知道鸟类并不像它们大脑大小所显示的那样简单。许多鸟类不仅表现出令人印象深刻的认知能力——比如使用甚至制造工具——对它们来说似乎太过先进，而且研究表明，许多鸟类的大脑中比同样体积的哺乳动物甚至灵长类动物有更多的神经元。

And now, according to the authors of the new study, these small-brained birds are challenging what we thought we knew about the evolution of multilevel societies. Not only have vulturine guineafowl achieved a format of social organization once thought to be uniquely human, but their long-overlooked society suggests this kind of phenomenon may be more common in nature than we realized.

现在，根据这项新研究的作者所说，这些小脑袋的鸟类正在挑战我们对多级社会进化的认知。秃鹰豚鼠不仅实现了一种曾被认为是人类独有的社会组织形式，而且它们长期被忽视的社会表明，这种现象在自然界可能比我们意识到的更为普遍。