aseymayo, this article, portions of which are quoted below, appeared in the Globe & Mail on 10/23/98:
Monkeys can count up to nine and can discriminate between groups of objects in ascending order.
Two researchers at Columbia University in New York report in the journal Science today that two rhesus monkeys called Rosencrantz and Macduff have proved that animals can think, even though they have no formal language.
. . .Elizabeth Brannon, said: “Though monkeys do not recognize the word ‘two’ or the numeral 2, they share with humans the ability to master simple arithmetic on at least the level of a two-year-old child. We don’t have direct evidence yet, but it seems likely that these monkeys, and other non-human primates, can count.”
Chimpanzees are humans’ closest animal relatives. Rosencrantz and Macduff are distant cousins. Yet when presented with 35 sets of images on a touch-sensitive screen, they learned to handle them in an ascending order.
They touched one square, two trees, three ovals and four flowers in that order – and were rewarded with a banana-flavoured delicacy. If they got the order wrong, the screen went black and the game began again. But they carried on playing with their touch-screen fruit machine and ended up performing what researchers described as “cognitive serial tasks” without any more instruction from the scientists.
“It’s like using your password to get money from a cash machine, but it is actually much harder for the monkeys,” Mr. Terrace said. “The pictures, and their position on the screen, change each time they try for another pellet of food. When you go to a cash machine, you don’t have to deal with the numbers being in strange positions each time. We ask a lot, cognitively speaking, of our non-human primate subjects.”
Having gotten the hang of one to four, the newly numerate monkeys were then tested on a different set of images, showing objects from five to nine. They did just as well. They could only have done this, the researchers say, if they had learned some numerical rule for ordering the contents of the pictures.
The examiners got tougher. They showed Rosencrantz and Macduff pictures with five and seven objects in them and asked them to touch them in ascending order. They did. “It shows that monkeys know things about numbers that we haven’t taught them,” Ms. Brannon said.
The latest research focused on a problem first raised by French philosopher Rene Descartes more than 300 years ago. He argued that “abstract thinking” required language, which made humans different from all other living things. Biologists have never been sure of that: Animals may not have conversations, but they quite clearly communicate with each other.
For a while anthropologists argued that humans were different because they used tools. But zoologists pointed out that tool-using, too, was quite common in the animal world. Since then the debate has focused on difficult-to-define ideas such as “consciousness” and on particular social behaviour using symbols or sounds.
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