From the New York Times 鴿子獼猴大作戰!

 

圖片William van der Vliet

圖片說明

一隻鴿子正在作算術題。

當牠啄一個圖像時(右圖)，圖像四周會出現一個正方形框(左圖)

圖片Damian Scarf
圖片說明
本圖顯示出鴿子會分辨不同圖形與數量
並作出正確的排序與簡單的算術

別看鴿子天生小頭一粒
牠們其實跟猴子一樣聰明
(這邊的聰明指的是簡單的算術
跟發明火箭與探測外太空無關)

紐約時報日前有一篇報導
顯示鴿子其實還蠻聰明的
雖說這些鳥兒要訓練一年才會做簡單算術題
不過結果已經讓科學家大感驚異

How Smart Is This Bird? Let It Count the Ways

By JAMES GORMAN

Published: December 22, 2011

By now, the intelligence of birds is well known. Alex the African gray parrot非洲灰鸚鵡 had great verbal skills. Scrub jays叢鴉(一種藍色的鳥), which hide caches of seeds儲存/囤積種子 and other food, have remarkable memories. And New Caledonian crows新克里多尼亞烏鴉make and use tools in ways that would put the average home plumber指自己DIY修理家裡水管的人 to shame.

Pigeons, it turns out, are no slouches絕非等閒之輩(也就是跟上述這些聰明的動物相比)此字本義指懶散或是無精打采 either. It was known that they could count.(鴿子會數數字) But all sorts of animals, including bees, can count. Pigeons have now shown that they can learn abstract rules about numbers, an ability that until now had been demonstrated only in primates靈長類. In the 1990s scientists trained rhesus monkeys印度產的猴恆河獼猴 to look at groups of items on a screen and to rank them from the lowest number of items to the highest.(這類猴子能夠觀察板子上列出的不同數量與類別物件，然後按照大小排列，從數量最少的依序排到數量最多的)

They learned to rank groups of one, two and three items in various sizes and shapes.(這些猴子還會按照三種不同物件，根據大小與形狀排列整理) When tested, they were able to do the task even when unfamiliar numbers of things were introduced. 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. (測試過程中，研究人員會加入新的物件形狀與數量，這些猴子依舊能夠分辨並且按照類別與數字大小排序。這些猴子也曉得2比1大，3比2多，5也比2多的道理)

Damian Scarf, a postdoctoral博士後研究 fellow at the University of Otago紐西蘭奧塔哥大學(歷史最悠久的大學), in New Zealand, tried the same experiment with pigeons, and he and two colleagues report in the current issue of the journal Science 科學期刊that the pigeons did just as well as the monkeys.

Elizabeth Brannon, a professor of psychology and neuroscience心理學與神經科學 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.

Score one for the birds.(鴿子與猴子的智商戰爭中，這邊鳥類得一分) The pigeons had learned an abstract rule抽象規則: peck啄 images on a screen in order, lower numbers to higher. 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.

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.

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對於數字的能力是個別進化的結果, or of both pigeons and primates using an ability that was already present in their last common ancestor又或者這種能力在鴿子與靈長類兩者本身的共同祖先裡就存在.

That would really be something, because the common ancestor of pigeons and primates would have been alive around 300 million years ago靈長類與鴿子的共同祖先早在三億年前就存在, before dinosaurs恐龍 and mammals哺乳類動物. 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數字能力 he tested evolved separately.研究學者猜測數字能力可能是個別進化的結果 “I can definitely see why both monkeys and pigeons could profit from this ability,” he said.

No testing has been done with numbers greater than nine, so whether a pigeon can count large numbers of bread crumbs麵包屑 or popcorn kernels爆米花還沒爆開之前的玉米粒 is a question still open to investigation.