為什么黑猩猩喜歡向樹(shù)扔石頭?

為什么黑猩猩喜歡向樹(shù)扔石頭?

Researchers recently discovered some unusual behavior in chimps living in the forests of West Africa. An adult male in the wild would pick up a rock, throw it at a tree while yelling, and then run away.

研究人員最近在生活在西非森林中的黑猩猩身上發(fā)現(xiàn)了一些不尋常的行為。野外的成年雄性會(huì)撿起一塊石頭，一邊大喊大叫一邊扔向一棵樹(shù)，然后逃跑。

Photo: Abeselom Zerit/Shutterstock

Although researchers aren't certain why the chimps fling the rocks, they have a hint: The chimps seem to prefer trees that create longer-lasting, more resonant sounds when struck.

雖然研究人員還不確定為什么黑猩猩會(huì)扔石頭，但他們有一個(gè)提示:黑猩猩似乎更喜歡在受到撞擊時(shí)發(fā)出更持久、更共振的聲音的樹(shù)。

A team of researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, first uncovered this behavior three years ago. Because the actions appeared to be localized, the researchers suggested the purpose was a local tradition and was likely part of some sort of ritual, Phys.org reports. But they weren't sure what purpose the ritual served.

德國(guó)萊比錫馬克斯·普朗克進(jìn)化人類(lèi)學(xué)研究所的一組研究人員三年前首次發(fā)現(xiàn)了這種行為。因?yàn)檫@些行為似乎是局部的，研究人員認(rèn)為這是當(dāng)?shù)氐囊环N傳統(tǒng)，可能是某種儀式的一部分，Phys.org報(bào)道。但他們不確定這種儀式的目的是什么。

So the group devised more experiments to determine why the chimps were so interested in lobbing rocks at trees. This time around, they went to the same areas but set up microphones to capture the sounds of the stones as they were thrown. While waiting for the chimps to hurl the rocks, the researchers threw the stones at 13 different kinds of trees in various situations.

因此，研究小組設(shè)計(jì)了更多的實(shí)驗(yàn)來(lái)確定為什么黑猩猩對(duì)用石頭砸樹(shù)如此感興趣。這一次，他們?nèi)チ送瑯拥牡胤?，但設(shè)置了麥克風(fēng)來(lái)捕捉扔石頭的聲音。在等待黑猩猩投擲石塊時(shí)，研究人員在不同的情況下向13種不同的樹(shù)木投擲石塊。

"It was quite fun, I have to say," coauthor and primatologist Ammie Kalan tells Science.

“我不得不說(shuō)，這很有趣，”合著者兼靈長(zhǎng)類(lèi)動(dòng)物學(xué)家阿莫米卡蘭告訴《科學(xué)》雜志。

Researchers analyzed all the recordings and found that the chimps tended to prefer throwing rocks at trees that made lower, longer-lasting sounds. Often these were trees that had exposed roots.

研究人員分析了所有的錄音，發(fā)現(xiàn)黑猩猩更喜歡向發(fā)出低而持久聲音的樹(shù)扔石頭。這些樹(shù)的根常常暴露在外。

In their findings, published in Biology Letters, the researchers write that "low-frequency sounds travel further in the environment and are better suited for long-distance communication." In addition, more resonant sounds will last longer in the environment.

在他們發(fā)表在《生物學(xué)快報(bào)》上的研究結(jié)果中，研究人員寫(xiě)道:“低頻聲音在環(huán)境中傳播得更遠(yuǎn)，更適合遠(yuǎn)距離交流。”此外，更有共鳴的聲音在環(huán)境中會(huì)持續(xù)更長(zhǎng)的時(shí)間。

But if chimps were looking to communicate, it would be more effective for them to drum on the trees or choose the ones that made the loudest noises when struck.

但是，如果黑猩猩想要交流，對(duì)它們來(lái)說(shuō)，在樹(shù)上敲鼓或者選擇那些在被擊打時(shí)發(fā)出最大聲音的聲音會(huì)更有效。

Because the researchers saw chimps stick to the same trees and never choose new ones, location could be a factor. Kalan tells Science that maybe the locations of the trees have something to do with nearby resources like food and water, and the sound is a signal to others where to find them.

因?yàn)檠芯咳藛T發(fā)現(xiàn)黑猩猩們總是呆在同一棵樹(shù)上，從不選擇新的樹(shù)，所以位置可能是一個(gè)因素?？ㄌm告訴《科學(xué)》雜志說(shuō)，也許這些樹(shù)的位置與附近的資源有關(guān)，比如食物和水，而這些聲音是給其他人找到它們的信號(hào)。