鴿子竟是數學高手?

By now, the intelligence of birds is well known. Alex the African gray parrot had great verbal skills. Scrub jays, which hide caches of seeds and other food, have remarkable memories. And New Caledonian crows make and use tools in ways that would put the average home plumber to shame。

衆所周知，鳥類極爲聰明。一隻名叫阿歷克斯的非洲灰鸚鵡有不同尋常的口語能力；灌叢鴉能祕密隱藏種子和其他食物，有很強的記憶力；新喀里多尼亞鴉製作和使用工具的方式能讓普通的家庭管道工自愧弗如。

Pigeons, it turns out, are no slouches either. It was known that they could count. But all sorts of animals, including bees, can count。

事實證明，鴿子的智力也不賴。它們會數數，這是盡人皆知的事實。但很多種動物，包括蜜峯，也會數數。

Pigeons have now shown that they can learn abstract rules about numbers, an ability that until now had been demonstrated only in primates。

近來人們研究發現，鴿子能學習抽象的數字規則，而這項能力目前爲止僅在靈長目動物身上得以證實。

In the 1990s scientists trained rhesus monkeys to look at groups of items on a screen and to rank them from the lowest number of items to the highest。

在20世紀90年代，科學家們訓練恆河猴，讓它們看屏幕上的幾組物品，並按物品數量從少到多的順序進行排列。

They learned to rank groups of one, two and three items in various sizes and shapes. When tested, they were able to do the task even when unfamiliar numbers of things were introduced。

它們學會了按數量多少對幾組物品進行排列， 每組都包含了一個、兩個或三個不同形狀和大小的物品 。在測試時，即使物品的數量它們不熟悉，也能完成任務。

In other words, having learned that two was more than one and three more than two, they could also figure out that five was more than two, or eight more than six。

也就是說，學會了兩個比一個多，三個比兩個多後，它們能夠推理出五個比兩個多，或八個比六個多。

Damian Scarf, a postdoctoral fellow at the University of Otago, in New Zealand, tried the same experiment with pigeons, and he and two colleagues report in the current issue of the journal Science that the pigeons did just as well as the monkeys。

達米安·斯卡夫是新西蘭奧塔戈大學的博士後研究員，他對鴿子做了同樣的實驗。他和兩個同事在本期的《科學》期刊上稱鴿子在這方面的表現和猴子一樣好。

Elizabeth Brannon, a professor of psychology and neuroscience at Duke University, and one of the scientists who did the original experiments with monkeys, was impressed by the new results. “Their performance looks just like the monkeys’,” she said。

杜克大學心理學和神經科學教授伊利莎白·布蘭農，是最初給猴子做這種實驗的科學家之一，對結果感到非常驚訝。“它們的表現竟和猴子一樣。” 她說。

Score one for the birds. The pigeons had learned an abstract rule: peck images on a screen in order, lower numbers to higher。

給鳥類記上一分吧。鴿子已學會了一條抽象規則：按照數量從少到多的順序輕啄屏幕上的圖像。

It may have taken a year of training, with different shapes, sizes and colors of items, always in groups of one, two or three, but all that work paid off when it was time for higher math。

訓練時每組圖像都包含一個、兩個或三個形狀、大小、顏色各異的物品。這樣的訓練可能需要一年，但是等它們學習複雜點兒的數學時，就會發現這些付出是值得的。

Given groups of six and nine, they could pick, or peck, the images in the right order. This is one more bit of evidence of how smart birds really are, and it is intriguing because the pigeons’ performance was so similar to the monkeys’. “I was surprised,” Dr. Scarf said。

給它們幾組包含六個和九個物品的圖像，它們也能按正確順序挑選或輕啄圖像，證明了鳥類的確很聰明。這很耐人尋味，因爲鴿子的表現和猴子的表現不相上下。“我很吃驚。”斯卡夫博士說。

He and his colleagues wrote that the common ability to learn rules about numbers is an example either of different groups — birds and primates, in this case — evolving these abilities separately, or of both pigeons and primates using an ability that was already present in their last common ancestor。

他和同事寫道：鴿子和猴子都具有學習數字規則的能力，這表明不同的羣組—這個案例中是鳥類和靈長類—要麼是分別進化出這些功能，要麼是遺傳上一個共同祖先的能力。

That would really be something, because the common ancestor of pigeons and primates would have been alive around 300 million years ago, before dinosaurs and mammals. It may be that counting was already important, but Dr. Scarf said that if he had to guess, he would lean toward the idea that the numerical ability he tested evolved separately. “I can definitely see why both monkeys and pigeons could profit from this ability,” he said。

如果這項能力來自共同的祖先，那會意義非凡，因爲鴿子和靈長類的共同祖先離現在已有三億年了，那時恐龍和哺乳動物還沒出現呢，很可能在當時數數已是很重要的能力了。但斯卡夫博士表示，如果讓他進行猜測，他更傾向於這種能力是分別演化的這一觀點。“我非常清楚爲什麼猴子和鴿子都能從這項能力中受益。”他說。

No testing has been done with numbers greater than nine, so whether a pigeon can count large numbers of bread crumbs or popcorn kernels is a question still open to investigation。

目前還沒有大於9的數字測驗，所以鴿子會不會數更多的麪包屑或爆米花還有待進一步研究。