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我搜了半天在Scientific American上搜到的，有关红毛猩猩的用树皮剥壳~有中英的对照~希望有帮助！！ Technology in the Swamp We were initially attracted to the swamp because it sheltered disproportionately high numbers of orangutans—unlike the islands' dryland forests, the moist swamp habitat supplies abundant food for the apes year-round and can thus support a large population. We worked in an area near Suaq Balimbing in the Kluet swamp [see map at left], which may have been paradise for orangutans but, with its sticky mud, profusion of biting insects, and oppressive heat and humidity, was hell for researchers.
One of our first finds in this unlikely setting astonished us: the Suaq orangutans created and wielded a variety of tools. Although captive red apes are avid tool users, the most striking feature of tool use among the wild orangutans observed until then was its absence. The animals at Suaq ply their tools for two major purposes. First, they hunt for ants, termites and, especially, honey (mainly that of stingless bees)—more so than all their fellow orangutans elsewhere. They often cast discerning glances at tree trunks, looking for air traffic in and out of small holes. Once discovered, the holes become the focus of visual and then manual inspection by a poking and picking finger. Usually the finger is not long enough, and the orangutan prepares a stick tool. After carefully inserting the tool, the ape delicately moves it back and forth, and then withdraws it, licks it off and sticks it back in. Most of this “manipulation” is done with the tool clenched between the teeth; only the largest tools, used primarily to hammer chunks off termite nests, are handled.
The second context in which the Suaq apes employ tools involves the fruit of the Neesia. This tree produces woody, five-angled capsules up to 10 inches long and four inches wide. The capsules are filled with brown seeds the size of lima beans, which, because they contain nearly 50 percent fat, are highly nutritious—a rare and sought-after treat in a natural habitat without fast food. The tree protects its seeds by growing a very tough husk. When the seeds are ripe, however, the husk begins to split open; the cracks gradually widen, exposing neat rows of seeds, which have grown nice red attachments (arils) that contain some 80 percent fat. To discourage seed predators further, a mass of razor-sharp needles fills the husk. The orangutans at Suaq strip the bark off short, straight twigs, which they then hold in their mouths and insert into the cracks. By moving the tool up and down inside the crack, the animal detaches the seeds from their stalks. After this maneuver, it can drop the seeds straight into its mouth. Late in the season, the orangutans eat only the red arils, deploying the same technique to get at them without injury.
Both these methods of fashioning sticks for foraging are ubiquitous at Suaq. In general, “fishing” in tree holes is occasional and lasts only a few minutes, but when Neesia fruits ripen, the apes devote most of their waking hours to ferreting out the seeds or arils, and we see them grow fatter and sleeker day by day. Why the Tool Use Is Cultural What explains this curious concentration of tool use when wild orangutans elsewhere show so little propensity? We doubt that the animals at Suaq are intrinsically smarter: the observation that most captive members of this species can learn to use tools suggests that the basic brain capacity to do so is present.
So we reasoned that their environment might hold the answer. The orangutans studied before mostly live in dry forest, and the swamp furnishes a uniquely lush habitat. More insects make their nests in the tree holes there than in forests on dry land, and Neesia grows only in wet places, usually near flowing water. Tempting as the environmental explanation sounds, however, it does not explain why orangutans in several populations outside Suaq ignore altogether these same rich food sources. Nor does it explain why some populations that do eat the seeds harvest them without tools (which results, of course, in their eating much less than the orangutans at Suaq do). The same holds for tree-hole tools. Occasionally, when the nearby hills—which have dryland forests—show massive fruiting, the Suaq orangutans go there to indulge, and while they are gathering fruit they use tools to exploit the contents of tree holes. The hill habitat is a dime a dozen through out the orangutan's geographic range, so if tools can be used on the hillsides above Suaq, why not everywhere?
Another suggestion we considered, captured in the old adage that necessity is the mother of invention, is that the Suaq animals, living at such high density, have much more competition for provisions. Consequently, many would be left without food unless they could get at the hard-to-reach supplies—that is, they need tools in order to eat. The strongest argument against this possibility is that the sweet or fat foods that the tools make accessible sit very high on the orangutan preference list and should therefore be sought by these animals everywhere. For instance, red apes in all locations are willing to be stung many times by honeybees to get at their honey. So the necessity idea does not hold much water either.
A different possibility is that these behaviors are innovative techniques a couple of clever orangutans invented, which then spread and persisted in the population because other individuals learned by observing these experts. In other words, the tool use is cultural. A major obstacle to studying culture in nature is that, barring experimental introductions, we can never demonstrate convincingly that an animal we observe invents some new trick rather than simply applying a well-remembered but rarely practiced habit. Neither can we prove that one individual learned a new skill from another group member rather than figuring out what to do on its own. Although we can show that orangutans in the lab are capable of observing and learning socially, such studies tell us nothing about culture in nature—neither what it is generally about nor how much of it exists. So field-workers have had to develop a system of criteria to demonstrate that a certain behavior has a cultural basis.
First, the behavior must vary geographically, showing that it was invented somewhere, and it must be common where it is found, showing that it spread and persisted in a population. The tool uses at Suaq easily pass these first two tests. The second step is to eliminate simpler explanations that produce the same spatial pattern but without involving social learning. We have already excluded an ecological explanation, in which individuals exposed to a particular habitat independently converge on the same skill. We can also eliminate genetics because of the fact that most captive orangutans can learn to use tools.
The third and most stringent test is that we must be able to find geographic distributions of behavior that can be explained by culture and are not easily explained any other way. One key pattern would be the presence of a behavior in one place and its absence beyond some natural barrier to dispersal. In the case of the tool users at Suaq, the geographic distribution of Neesia gave us decisive clues. Neesia trees (and orangutans) occur on both sides of the wide Alas River. In the Singkil swamp, however, just south of Suaq and on the same side of the Alas River [see map on opposite page], tools littered the floor, whereas in Batu-Batu swamp across the river they were conspicuously absent, despite our numerous visits in different years. In Batu-Batu, we did find that many of the fruits were ripped apart, showing that these orangutans ate Neesia seeds in the same way as their colleagues did at a site called Gunung Palung in distant Borneo but in a way completely different from their cousins right across the river in Singkil.
Batu-Batu is a small swamp area, and it does not contain much of the best swamp forest; thus, it supports a limited number of orangutans. We do not know whether tool use was never invented there or whether it could not be maintained in the smaller population, but we do know that migrants from across the river never brought it in because the Alas is so wide there that it is absolutely impassable for an orangutan. Where it is passable, farther upriver, Neesia occasionally grows, but the orangutans in that area ignore it altogether, apparently unaware of its rich offerings. A cultural interpretation, then, most parsimoniously explains the unexpected juxtaposition of knowledgeable tool users and brute-force foragers living practically next door to one another, as well as the presence of ignoramuses farther upriver. 沼澤裡的技術 我們決定到沼澤區去研究紅毛猩猩，一開始是因為那裡的紅毛猩猩特別多。潮濕的沼澤棲境與乾地的森林不同，整年都有豐富的食物供猩猩食用，因此能夠供養大量的紅毛猩猩在那裡生活。我們在庫魯依特沼澤區（Kluet swamp），接近斯瓦克楊桃園（Suaq Balimbing）的地方（見左圖），從事田野觀察。那兒也許是紅毛猩猩的天堂，對研究者可是地獄：地面黏黏的泥巴教人行動不便，昆蟲叮著人咬教人無所逃遁，空氣悶熱潮濕教人透不過氣。
在這個特別的環境中，我們最初的發現就令人驚訝：斯瓦克的紅毛猩猩會製造、使用許多不同的工具。雖然在人工環境中生活的紅毛猩猩很會使用工具，然而學者觀察野生紅毛猩猩的共同印象都是：牠們不使用工具。斯瓦克的紅毛猩猩使用工具，主要目的有二。第一，牠們較常捕食螞蟻、白蟻，並特別喜愛蜂蜜（主要是無刺蜜蜂的產品），其他地方的同胞比不上。牠們常常盯著樹幹看，尋找昆蟲在小洞飛進飛出的動靜。一旦發現了，那些洞就成為牠們視覺的焦點，接著就以手指插入探索。通常手指都不夠長，紅毛猩猩就會以樹的枝條製造工具。牠們小心插入工具後，靈巧地移進移出，再抽出將枝條舔過，然後再度插入。這種操作大部份是以牙齒咬住工具進行；只有最大的工具才以手操作，主要用來敲擊白蟻巢，敲碎了找白蟻吃。
斯瓦克的紅毛猩猩使用工具的第二種情況，涉及尼西亞樹（Neesia aquatica）的果實。這種果實是五角形的木質蒴果，25公分長，10公分寬。蒴果中藏有皇帝豆大小的褐色種子，那些種子將近50%是脂肪，非常營養；在沒有速食店的自然棲境中，那是希罕而搶手的美食。尼西亞樹以非常堅韌的果皮保護種子，為了嚇阻專門吃種子的動物，果皮上佈滿了尖銳的刺。不過，種子成熟後，果皮就會裂開；裂縫逐漸擴大，將排列整齊的種子暴露出來，種子表面還長出紅色鮮豔的假種皮，脂肪含量達80%。斯瓦克紅毛猩猩會找短而直的樹枝，剝去樹皮，含在嘴裡，插入果皮上的裂縫。牠們以工具在縫裡上下游移，使種子脫離周遭組織，然後就能將種子直接倒入嘴裡。到了季節晚期，紅毛猩猩只吃紅色的假種皮，牠們以同樣的技術取得假種皮而不受傷。
這兩種以修整過的樹枝覓食的方法，斯瓦克的紅毛猩猩都會。一般而言，釣樹洞中的蟲吃，牠們只是偶一為之，每次持續幾分鐘而已。但是尼西亞果成熟時，紅毛猩猩醒著的時間大多都在弄種子或假種皮吃，我們就眼看著牠們身體越來越肥，體毛越來越油亮。 為什麼使用工具是文化行為 為什麼只有斯瓦克的野生紅毛猩猩使用工具，其他地方的就缺乏這種意向？莫非斯瓦克的紅毛猩猩比較聰明？可是大多數生活在人工環境中的紅毛猩猩都能學會使用工具，可見牠們都有從事這種行為的基本腦力。
因此我們推測，斯瓦克的環境可能是關鍵。過去學者研究的野生紅毛猩猩大多生活在乾燥的森林中，而沼澤棲境鬱鬱蔥蔥，極為獨特。這裡在樹洞裡築巢的昆蟲，數量比乾燥森林中多得多；尼西亞樹只在濕地生長，通常在接近流水的地方。不過，環境理論固然誘人，卻不能解釋斯瓦克附近幾個紅毛猩猩族群，為什麼對這些營養豐富的食物資源統統都不在意；也無法解釋，為什麼有些食用尼西亞種子的族群不利用工具（牠們吃下的尼西亞種子，因而比斯瓦克的同胞少得太多了）。同樣的情形也發生在利用樹洞食物的工具上。偶爾，斯瓦克附近山丘的乾地森林中有大量果實成熟了，斯瓦克的紅毛猩猩會到那裡去大快朵頤，牠們不但採集水果，還會順便以工具探索樹洞。在紅毛猩猩生活的地理範圍內，處處都有山丘棲境，因此，要是斯瓦克附近的山丘上會出現工具，其他地方為什麼不會？
於是我們考慮了另一個理論：生活在斯瓦克的紅毛猩猩實在太多了，於是對食物的競爭更為激烈。俗話說得好，需求為發明之母。許多紅毛猩猩為了吃飽，非得開發本來難以利用的食物資源，不然只好坐以待斃。換言之，牠們得有工具，才能吃飽。反對這個理論的論點，以下面這一個最有力：糖份高、脂肪多的食物本來就是紅毛猩猩的最愛，無論牠們生活在哪裡，應該都會全力以赴，怎麼會只有斯瓦克的族群為取得美食而發明了工具呢？舉例來說，不論哪個地方的紅毛猩猩都愛吃蜂蜜，寧願冒蜂螫的風險，在所不惜。因此需求理論沒有什麼說服力。
另一個可能是，這些行為是幾頭聰明的紅毛猩猩發明的創新技術，其他個體透過觀察學會了，於是就在族群中散佈開來，並且傳遞到下一代。換言之，使用工具是文化行為。研究野生文化有個主要障礙，那就是：我們無法教人信服地證明，我們觀察的野生動物發明了一個新技術，而不只是展現早已記住卻很少實踐的習慣，除非我們設法將新技術教會牠們。我們也無法證明：某個個體從社群中的另一個成員學會了一個新技巧，而不是自己想出來的。雖然我們可以證明紅毛猩猩在實驗室中能夠彼此觀察與學習，這樣的研究並不能增進我們對野生文化的理解，無論是野生文化的一般性質或具體內容。因此，田野研究人員為了證明某個行為有文化基礎，就必須發展出一套判準。
首先，那個行為的分佈必須有地理變異，顯示它是在某地發明的；而在發現它的地方是共有的行為，表示它在族群中已散佈開，並且能代代相傳。斯瓦克的紅毛猩猩使用工具的行為，輕易就通過這兩個檢驗。其次，有些比較簡單的解釋，可以造成同樣的空間模式，但是與社會學習無關，研究者必須排除那些解釋。我們已經排除了生態解釋（生活在特定棲境中的個體會各自獨立發展出同一技術）。我們也排除了遺傳解釋，因為在人工環境中生活的紅毛猩猩大部份都能學會使用工具。
第三個也是最嚴格的檢驗是，我們必須找到能以文化解釋的地理分佈，而任何其他方式都不容易解釋。例如一個行為出現在某個地方，但是在某個自然的傳播障礙以外，它就消失了。這樣的分佈模式是關鍵證據。以斯瓦克的紅毛猩猩使用工具的行為來說，尼西亞樹的分佈是最重要的線索。阿拉斯河（Alas River，見下方地圖）是一條寬闊的河，兩側都有尼西亞樹與紅毛猩猩。辛及爾沼澤（Singkil swamp）位於斯瓦克的南方，與斯瓦克在河的同一側，那裡地面上可以見到猩猩丟棄的工具，與河對岸的巴圖巴圖沼澤（Batu-Batu swamp）形成強烈的對比；我們在好幾年內分別去了巴圖巴圖許多次，從來沒見過工具。在巴圖巴圖，我們的確發現有許多尼西亞果給撕開了，顯示這些紅毛猩猩食用尼西亞果的方法，與婆羅洲咕農巴龍（Gunung Palung）的遠親如出一轍，反而與對岸辛及爾的表親完全不同。
巴圖巴圖是一塊很小的沼澤地，那裡的森林資源算不上豐饒，因此能供養的紅毛猩猩並不多。我們無法確定那裡的紅毛猩猩究竟是從來沒有發明過工具，還是較小的族群中無法維持使用工具的行為；我們確實知道的是：阿拉斯河實在太寬，紅毛猩猩絕對無法渡過，於是從來沒有移民將這種行為傳播進去。在河的上游，牠們就能夠橫渡了，那裡偶爾有尼西亞樹生長，但是當地的紅毛猩猩完全不理會尼西亞果，顯然是不知道這種果子的價值。對同一種食物資源，相鄰的兩群中，一群懂得利用工具享用，另一群使用蠻力；而大河上游遠處還有一群暴殄天物的鄉巴佬。對這樣出人意料的發現，「文化」才能做最簡潔的解釋。 |
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发表于 2009-10-13 12:20:00
