這些鳥證明了你不需要一個(gè)大腦袋來(lái)適應(yīng)復(fù)雜的社交生活

這些鳥證明了你不需要一個(gè)大腦袋來(lái)適應(yīng)復(fù)雜的社交生活

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.

一項(xiàng)新的研究發(fā)現(xiàn)，鳥類可以形成復(fù)雜的、多層次的社會(huì)，這是一項(xiàng)以前只在人類和某些其它腦容量大的哺乳動(dòng)物身上才知道的壯舉，包括我們的一些靈長(zhǎng)類同胞，以及大象、海豚和長(zhǎng)頸鹿。

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.

這也進(jìn)一步證明，盡管鳥類的大腦相對(duì)較小，但它們比我們通常認(rèn)為的更聰明、更復(fù)雜。

Leveling up

升級(jí)

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.

這項(xiàng)研究的對(duì)象是禿鷲幾內(nèi)亞貓頭鷹，一種身體沉重的地面食性物種，原產(chǎn)于非洲東北部的灌木叢和草原。這些鳥是一個(gè)令人印象深刻的景象，有一個(gè)生動(dòng)的藍(lán)色胸部和長(zhǎng)有光澤的頸部羽毛，導(dǎo)致一個(gè)裸露的“禿鷹”的頭與強(qiáng)烈的紅色眼睛。現(xiàn)在，正如研究人員在《當(dāng)代生物學(xué)》雜志上報(bào)告的那樣，我們知道它們也生活在令人印象深刻的社會(huì)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.

生活在一個(gè)多層次的社會(huì)可以提供巨大的利益，社會(huì)的不同層次服務(wù)于特定的適應(yīng)性目的，以適應(yīng)不同的成本效益權(quán)衡。這包括最低層級(jí)的繁殖和社會(huì)支持，以及更高層級(jí)的合作狩獵和防御等額外福利。

Birds of a feather

物以類聚

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，根據(jù)馬克斯·普朗克動(dòng)物行為研究所的一份聲明，在這項(xiàng)新研究中，研究人員發(fā)現(xiàn)，禿鷹豚鼠是一個(gè)“引人注目的例外”。該研究的作者報(bào)告說(shuō)，這些鳥把自己組織成高度團(tuán)結(jié)的社會(huì)群體，但沒有群居鳥類中常見的“典型的群體間攻擊”。他們用一個(gè)相對(duì)較小的大腦實(shí)現(xiàn)了這一點(diǎn)，據(jù)報(bào)道，即使以鳥類的標(biāo)準(zhǔn)來(lái)衡量，大腦也很小。

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.

研究人員說(shuō)，結(jié)果顯示，不同群體的禿鷹豚鼠會(huì)根據(jù)喜好而相互聯(lián)系，而不是隨機(jī)相遇。研究還發(fā)現(xiàn)，群體間的聯(lián)系更有可能發(fā)生在特定的季節(jié)和景觀的特定地點(diǎn)。

Secret society

秘密社團(tuán)

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.

我們已經(jīng)知道鳥類并不像它們大腦大小所顯示的那樣簡(jiǎn)單。許多鳥類不僅表現(xiàn)出令人印象深刻的認(rèn)知能力——比如使用甚至制造工具——對(duì)它們來(lái)說(shuō)似乎太過(guò)先進(jìn)，而且研究表明，許多鳥類的大腦中比同樣體積的哺乳動(dòng)物甚至靈長(zhǎng)類動(dòng)物有更多的神經(jīng)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.

現(xiàn)在，根據(jù)這項(xiàng)新研究的作者所說(shuō)，這些小腦袋的鳥類正在挑戰(zhàn)我們對(duì)多級(jí)社會(huì)進(jìn)化的認(rèn)知。禿鷹豚鼠不僅實(shí)現(xiàn)了一種曾被認(rèn)為是人類獨(dú)有的社會(huì)組織形式，而且它們長(zhǎng)期被忽視的社會(huì)表明，這種現(xiàn)象在自然界可能比我們意識(shí)到的更為普遍。