[自然百科] 鳥界愛因斯坦鴿子能從1排到9

鳥界愛因斯坦鴿子能從1排到9

鴿子不僅認得路，它們還懂得數數字！過去認為只有靈長類動物才具有識別抽象數字概念的能力，但紐西蘭科學家發現，鴿子其實也擁有類似的識數才能，而且不比猩猩、獼猴差；據目前實驗證明，它們能正確由小至大排出數字1到9。

鴿子也懂得數數字？

紐西蘭奧塔葛大學(University of Otago)研究人員在實驗初始時，設置了共35組圖片，每組圖片有1至3個形狀、大小及顏色不同的物體，但研究團隊只要鴿子辨識出物體的“數量”；只要它們能從小到大的順序啄點圖片，就能獲得小麥當獎勵。

鴿子很容易就啄出1至3個物體的圖片，接下來辨識範圍擴大到1至9個物體，鴿子依然能夠正確排出順序。此外，若圖片中物體數量的差距越大，鴿子就越能夠快速、正確排序，例如3和8，就比7和8容易辨識。

國外媒體疑惑鴿子是否為“鳥界愛因斯坦”？研究主持人史卡夫(Damian Scarf)表示，鳥類的腦部結構與人不同，因此鴿子識數的過程與人類也不盡相同；然而鳥類之間，很可能共享這一套複雜的思維能力，現在也以紐西蘭的食肉鸚鵡進行類似實驗，希望找出其中關聯。

How Smart Is This Bird? Let It Count the Ways

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.

Pigeons, it turns out, are no slouches either. It was known that they could count. 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. 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.

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. 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.

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.

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.

Score one for the birds. The pigeons had learned an abstract rule: peck 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, or of both pigeons and primates using an ability that was already present in their last common ancestor.
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.

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.