A new study of corvid birds underscores how biology, environment, and social life allow young birds and humans to learn difficult skills that improve survival
一項鴉科鳥類的新研究強調了，生活方式與現象、環境及社交生活，如何使幼鳥及人類得以學習，提升生存能力的困難技能。
The current study analyzes social and life-history data from several thousand songbirds, including 127 corvids, the family that includes jays, crows, ravens, and magpies. Results show that corvids are unusual in having larger brains and “extended childhoods,” where parents provide the young with a safe haven to learn and practice skills they need to survive as adults. These findings shed light on how extended parenting in humans facilitated the evolution of our extraordinarily large brains.
當前的該項研究分析了，來自包括松鴉、烏鴉、渡鴉及喜鵲等，127種鴉科，數千隻鳴禽的社交及生活史數據。結果顯示，鴉科具有異常大的大腦，及“長時間的幼年時期”。在此期間，父母提供了，雛鳥學習及練習成鳥時，生存所需技能的安全庇護所。此些研究發現闡明了，長時間的養育，在人類中，如何促進咱們特大大腦的演化。
Humans are unusual, even among primates, in the length of our "extended childhood." Scientists think that this period of childhood and adolescence, which gives us lots of time to explore, create, and learn, is a key reason why we are smart enough to learn skills that take years to master.
即使在靈長類動物中，人類在 “長時間之幼年時期”的長度上，也是不尋常的。科學家們認為，該賦予人類大量進行探索、創造及學習時間的幼年及青少年時期，是為何人類聰明足以學習，需要數年來學會之技能的一種原因。
But humans are not the only species with an extended childhood. Elephants, some bats, whales, dolphins, and some birds - especially corvids - also have them. But does an extended childhood make other species smart too, and if so, what is the role of parenting?
不過，人類並非具有長時間，幼年時期的唯一物種。大象、某些蝙蝠、鯨魚、海豚及某些鳥類(特別是鴉科)也有。不過，長時間的幼年時期，也使得其他物種變聰明？如果是的話，什麼是餵養的角色？
圖1. 野生西伯利亞松鴉的父母(左)與其繼續餵養的後代(右)一起覓食。 (圖援用自原文)
A team of scientists from the Max Planck Institute for the Science of Human History, the University of Konstanz and the UK tackled these questions by combining the results of their own fieldwork on two corvid species - Siberian jays and New Caledonian crows - with published data from 127 corvid species and several thousand species in the passerine (songbird) order.
一支來自德國馬克斯普朗克人類史科學研究所、康斯坦茨大學及英國的科學家團隊，藉由結合其針對，西伯利亞松鴉與新喀里多尼亞烏鴉，這兩種鴉科物種的野外考察研究結果，及來自127種鴉科物種與雀形目鳥類(鳴禽)中，數千物種經公佈的數據，解決了此些問題。
The study, published in Philosophical Transactions of the Royal Society B, offers a groundbreaking new view on the evolution of intelligence, where parenting takes center stage.
該項發表於英國《皇家學會哲學學報B刊》的研究提供了，有關餵養進入智力發展，主要階段之新見解的一項突破。
Researchers spent years observing two bird species in the wild to understand how young birds' learning is related to parenting received during adolescence and survival in adulthood. At a study site in Sweden, researchers used field experiments to test the ability of young Siberian jays to learn crucial life skills: recognizing a dangerous predator and opening a puzzle box to access food.
研究人員們，花了數年時間，觀察於野地中的兩種鳥類物種，來瞭解幼鳥的學習，如何與青年期獲得的餵養及成年期的生存有所關聯。在瑞典的一處研究場所，研究人員們使用了諸多野外實驗，來測試西伯利亞幼松鴉，學習關鍵生活技能的能力：也就是，識別危險捕食者及打開智力玩具盒，來獲取食物。
Across the northern Palearctic, Siberian jays live in family groups which can include not only the young of a breeding pair, but also young that were born in other groups. These young can stay with the family group for up to four years. Young that stayed with their parents longer benefitted from being with their parents. They learned faster by watching their parents and received more food from their parents. As a consequence, they were more likely to live longer and to start their own family.
在整個古北區(地球八個生物地理領域之一，該區是最大的，橫跨喜馬拉雅山山麓以北的整個歐亞大陸及北非)北方，西伯利亞松鴉以不僅能包括，能繁殖的年輕松鴉對，而且也能包括出生於，其他群體之年輕松鴉的家式群體方式生活。此些年輕松鴉能逗留於這種家式群體中，長達四年。與其父母待在一起的年輕松鴉，從其父母獲益的時期較長。藉由觀察其父母及從其父母接受更多食物，此些年輕松鴉學習得更快。結果，它們更可能以此方式過活得更久，才開始自己的家庭。
At a study site in New Caledonia, researchers followed New Caledonian crows to track how juveniles learn a key survival skill: making tools for food retrieval. It takes about a year to learn this skill - a costly time investment for the parents who still have to feed the young. Surprisingly, these crows can stay with their parents for up to three years, allowing for a much longer “childhood” than most other crows.
在新喀里多尼亞的一處研究場所，研究人員們追蹤了新喀里多尼亞烏鴉，來追蹤該種年輕烏鴉，如何學習關鍵的生存技能：也就是，製作取得可能之食物的工具。學習此技能大約需要一年，就仍然必須餵養年輕烏鴉的父母來說，這是一項代價高的時間投資。令人訝異的是，此些烏鴉會與父母待在一起達三年。這為比大多數其他烏鴉，更長很多的“幼年時期”留出餘地。
Parents and other adults are extremely tolerant to young crows. While adults are using a tool to get food, they feed the juveniles, let them watch closely, and even tolerate tool theft and physical contact by juveniles. As a result of this tolerant learning environment, New Caledonian crows have the largest brain size for their body size of all corvids.
父母及其他成年烏鴉極度寬容年輕烏鴉，當成年烏鴉使用工具來取得食物的同時，它們也餵食年輕烏鴉，讓它們仔細觀察，甚至容忍年輕烏鴉偷竊工具，及遭年輕烏鴉身體接觸。由於這種寬容的學習環境，就所有鴉科的身軀尺寸而言，新喀里多尼亞烏鴉，具有最大的大腦尺寸。
The authors argue that the key role of parenting on the evolution of cognition has been overlooked so far. Often thought of as merely an inevitable chore, parental care is the reason children can spend their childhood learning and making mistakes.
此些撰文人認為，迄今為止，餵養在認知發展上的關鍵角色，一直遭忽略。經常被認為，只是一種必然的事務，父母的照顧是孩子們，度過其學習及犯錯誤之幼年時期的原因。
"Extended parenting has profound consequences for learning and intelligence," explains Michael Griesser of the University of Konstanz. "Learning opportunities arise from the interplay between extended childhood and extended parenting. The safe haven provided by extended parenting is critical for learning opportunities. It creates extended developmental periods that feed back into the extended childhood."
康斯坦茨大學的Michael Griesser解釋：「對學習及智力而言，長時間的餵養，具有深遠的影響。學習機會源自，長時間的幼年時期與長時間餵養之間的交互作用。對學習機會而言，這種由長時間餵養提供的安全庇護所，是至關重要的。這創造了，回饋到長時間之幼年時期的長時間發育時期。」
In addition to benefitting young learners, extended parenting helps pay for the costs of an extended childhood. Having to feed extra mouths is costly, but when there is enough food available in the environment, parents can afford to keep on feeding the young for longer.
除了使年輕學習者受益，長時間的餵養也有助於報償長時間之幼年時期的代價。必需多餵養數個月的代價是高的，不過當環境中有足夠食物可資取用時，父母負擔得起繼續餵養幼鳥達更長的時間。
With a safe haven, young birds have the time to grow a larger brain, learn difficult skills, and access vital food resources. These acquired skills lead to better survival, and possibly also allow the species to expand into new environments.
在獲得一種安全庇護所的情況下，幼鳥有時間生長較大的大腦、學習困難的技能及取得重要食物資源。此些後天技能帶來更佳的生存能力，且也可能使該物種擴展到新環境中。
The researchers used phylogenetic comparative methods to analyze the differences between corvids and all other passerines. Corvids have much larger brains relative to their body size, like humans. They also have prolonged developmental periods, both in the nest and after they leave - another characteristic of humans.
此些研究人員使用了種系發生的比較方法，來分析鴉科與所有其他雀形目鳥類之間的差異。如同人類，鴉科具有相對於其身軀尺寸，較大很多的大腦。於巢中及離巢後，它們也有拉長的發育期間。這是人類的另一種特性。
"Both humans and corvids spend their youth learning vital skills, surrounded by tolerant adults which support their long learning process,” explains Natalie Uomini of the Max Planck Institute. “Moreover, corvids and humans have the ability for lifelong learning - a flexible kind of intelligence which allows individuals to adapt to changing environments throughout their lifetime."
馬克斯普朗克人類史科學研究所的Natalie Uomini解釋：「人類及鴉科皆在青年時期學習重要技能，周遭有寬容的成人，支持其長時間的學習過程。此外，鴉科及人類皆有終身學習的能力。這是使個體得以適應一生中，變化之環境的一種適應性智力。」
In the light of this study, the importance of parenting comes into even greater focus. Parents have a vital role in helping young brains grow smarter. Children, like young birds, cannot learn skills in isolation. Instead they need a nurturing, supportive environment that allows the full potential of their large brains to develop.
鑒於該項研究，餵養的重要性成為更大焦點。在協助年輕人的大腦變得更聰明上，父母具有一種角色。如同幼鳥，兒童無法孤立地學習技能。而是，需要一種使其大腦得以發展充分潛能之養育、有支持作用的環境。
原文網址：https://www.shh.mpg.de/1715551/extended-parenting?c=1606725
翻譯：許東榮
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