AR-News: Matematical ability of animals (highlights)

[Andrew Gach]

Number of the beasts

New Scientist vol 181 issue 2431 - 24 January 2004, page 38

More and more animals are revealing unsuspected mathematical talents. And
they're teaching us a thing or two about how our own brains deal with
numbers, says Emily Sohn

MATHEMATICS often ranks alongside language and opposable thumbs as one of
those things that separate man from beast. But again and again, the beasts
are proving us wrong. "Every time people say animals can't do X," says Irene
Pepperberg, who has spent years studying the skills of an African grey
parrot named Alex, "we find yes, they can. They can do X + 1."

>From birds that count, to chimpanzees that add, to salamanders that know the
difference between two and three, it looks as though an inborn sense of
number is one of the most basic cognitive abilities around. And a range of
studies show that animals and people deal with numbers in some remarkably
similar ways.

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That numeracy skills are found throughout the animal world makes a lot of
sense. Figuring out which tree has more berries on it, or determining
whether there are more friends than enemies in an area, are matters of life
and death. "If you know there are six lions in the pride and you only see
four," says behavioural neuroscientist Randy Gallistel of Rutgers University
in New Jersey, "there is probably some survival value to wondering where the
other two are."

Not surprisingly, some animals are more gifted than others (see Graphic).
"You go from the very simplest perceptual recognition of bigger versus
smaller to the absolute be-all, end-all of being able to understand
complicated mathematical equations," says Pepperberg, who works at the
University of Arizona in Tucson and is also a visiting professor at the
Massachusetts Institute of Technology.
Alex, a 27-year-old parrot in Pepperberg's lab, for example, can count and
distinguish between more and less, among other skills. He can look at a
collection of blue and red blocks and tell how many blue blocks there are.
Pepperberg also believes that Alex is learning not only that the symbol "3"
represents "threeness", but also that the symbol "4" represents something
bigger. Chimpanzees can do similar tasks. Pigeons appear to be less numerate
but can distinguish between different numbers of objects, however big the
objects are or however much space they take up. Rats don't seem to grasp
abstract concepts of number at all, but can learn to press a lever close to
a specified number of times.

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For now, scientists are still trying to figure out just what animals can and
can't do in order to delve deeper into our mathematical heritage. In a study
published in Nature last April, for example, behavioural ecologist Bruce
Lyon at the University of California, Santa Cruz, found that wild coots can
count the eggs in their nests (vol 422, p 495). They then eject foreign eggs
laid by other birds trying to offload their parenting responsibilities and
add more of their own to compensate. "This was one of the very few studies
showing counting in a wild animal as opposed to a laboratory setting," says
Lyon. "So it connects counting back to the reason why they would be
counting."

And Uller's next plan is to do her salamander study with shrimp and food
pellets, to see if crustaceans will spontaneously go for more, just as
babies, primates and salamanders do."I'm going down the line here," she
says. "We are not in the insect domain yet. A colleague suggested we try
roaches - two breadcrumbs on the left, three on the right." She laughs.
"We're not there yet."

Full story
http://archive.newscientist.com/secure/article/article.jsp?id=mg18124315.600
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The power of one
The loner mathematician is a popular, if exaggerated, image. But new studies
suggest that in nature, mathematical skills and social skills are indeed a
rare combination.
"Orang-utans approach solving problems very, very differently from
chimpanzees and humans or even salamanders," says Robert Shumaker from the
Iowa Primate Learning Sanctuary in Des Moines. He thinks that social
pressures might explain why different species have evolved subtle
differences in their number skills.
One of the most telling examples involves self-restraint. Say you present an
animal with two piles of hard-to-resist food, such as gumdrops. If the
animal picks the lesser of two piles of gumdrops, it earns a larger reward.
Going for this delayed gratification requires a huge amount of self-control.
Orang-utans can do it. Chimpanzees can't.
Primatologist Sally Boysen of Ohio State University in Columbus has trained
chimpanzees to do almost everything else imaginable involving numbers. But
picking less food is something the animals just cannot do. "If, instead of
candy, I put Arabic numerals down, they didn't have any problem pointing to
the number "2" instead of the number "5" immediately," Boysen says. "They
knew the rules but they could just not inhibit going for the actual things.
It's as if the number symbol freed them from this biological dictate."
Chimpanzees are extremely social animals, constantly competing for
resources. They may just be hard-wired to pick more when it comes to food,
regardless of what the trainers says. Rhesus monkeys and capuchins have the
same problem, Boysen says, as do salamanders and pigeons.
Orang-utans, on the other hand, can pick the smaller of two quantities
without any problem at all, says Shumaker. Unlike chimps, orang-utans tend
to spend lots of time alone. Without pressure to compete, Shumaker says,
they may have better control over their minds and actions.





Emily Sohn
Emily Sohn is a science writer based in Minneapolis







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