哺乳動物并不像我們想象的那么獨特

鳥類和復雜社會的發(fā)現表明：哺乳動物并不像我們想象的那么獨特

It has long been thought that one of the reasons we humans developed large brains was to allow us to maintain complex social structures. But the social system of a small-headed guineafowl now suggests that large brains are not necessarily a requirement for complex multi-levelled societies.

長期以來，人們一直認為，我們人類發(fā)展大大腦的原因之一是讓我們能夠維持復雜的社會結構。但是現在，一只小腦袋禿鷲的社會系統(tǒng)表明，對于復雜的多層次社會來說，大腦袋并不一定是必需的。

Even amongst a crowd, vulturine guineafowl (Acryllium vulturinum) can find their friends, and keep track of their social status with hundreds of other individuals - a feat previously only known in mammals.

即使是在鳥群中，禿鷲也能找到自己的朋友，并與數百個其他個體保持聯(lián)系，這是一項以前只有哺乳動物才知道的壯舉。

Named for their bare head and neck, these strikingly red-eyed and blue-breasted social birds are found in Northeast Africa. They are often observed hanging out in groups, which in itself isn't unusual for birds. What's different here is that these groups also have consistent associations with other groups, adding an entire social tier to their bird society.

這些赤裸的頭和脖子、被命名為紅眼睛和藍胸的群居鳥分布在非洲東北部。它們經常成群結隊地出沒，這對鳥類來說并不罕見。不同的是，這些群體也與其他群體有著一致的聯(lián)系，為他們的鳥類社會增加了一個完整的社會層次。

Researchers from the Max Planck Institute and University of Konstanz in Germany tracked the social interactions of a population of over 440 adult vulturine guineafowl in Kenya for several years. They discovered that this large population was made up of 18 social groups, with 13 to 65 individuals in each.

德國馬克斯普朗克研究所和康斯坦茨大學的研究人員，數年來跟蹤了肯尼亞440多只成年禿鷲的社會互動，他們發(fā)現，這個龐大的群體由18個社會群體組成，每個群體有13到65個成員。

The groups consist of multiple males and females, including breeding pairs and non-breeders, and remain stable across the seasons. They intermingle with other groups during communal roosting at night and during daytime activities: For example, certain groups choose to roost with each other at night, even if they do not share the same territory or hang out together during the day.

這些群體由多個雄性和雌性組成，包括繁殖對和非繁殖者，并在整個季節(jié)保持穩(wěn)定。它們在夜間和白天的公共棲息活動中與其他群體混合：例如，某些群體選擇在夜間相互棲息，即使它們在白天不共享同一領土或一起閑逛。

After mingling, individual birds consistently split back into their original groups, meaning they understand who is part of their group and who isn't. The researchers even suspect the birds have something akin to smaller clusters of friends within these groups.

在混合之后，每一只鳥都會重新回到原來的群，這意味著它們知道誰是它們群的一部分，誰不是。研究人員甚至懷疑這些鳥有一些類似于這些群中較小的朋友群的東西。

"To our knowledge, this is the first time a social structure like this has been described for birds," said ethologist Danai Papageorgiou from the Max Planck Institute.

“據我們所知，這是首次對鳥類的社會結構進行這樣的描述，”馬克斯·普朗克研究所的動物行為學家達納伊·帕佩佐羅說。

By following 58 of the birds with solar GPS devices, the researchers were able to analyse these group interactions and show that groups were associating with specific other groups by choice, rather than chance.

通過追蹤58只帶有太陽能GPS設備的鳥類，研究人員能夠分析這些群體之間的相互作用，并表明這些群體是通過選擇而非偶然地與特定的其他群體聯(lián)系在一起的。

So, it seems vulturine guineafowl maintain complex, multi-levelled social circles despite possessing rather tiny brains.

因此，盡管禿鷲的大腦相當小，但它似乎維持著復雜的、多層次的社交圈。

"This discovery raises a lot of questions about the mechanisms underlying complex societies and has opened up exciting possibilities of exploring what is it about this bird that has made them evolve a social system that is in many ways more comparable to a primate than to other birds," says ethologist Damien Farine from the Max Planck Institute.

馬克斯·普朗克研究所的動物動物學家達米恩·法林說：“這一發(fā)現提出了許多關于復雜社會的機制的問題，并為探索這種鳥類，到底是如何進化成一種在多方面優(yōu)于其他鳥類，并能與靈長類動物相媲美的社會系統(tǒng)的問題，開辟了令人興奮的可能性。”。

This research was published in Current Biology.

這項研究發(fā)表在《當代生物學》雜志上。