Non-Human Intelligence
(Top Posts - Science - 022009)

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Monkeys Can Subtract, Study Finds
Christine Dell'Amore in Chicago
National Geographic News

February 18, 2009
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Add this to the growing list of reasons humans
aren't so special, after all: Monkeys can subtract.

The discovery marks the first time a nonhuman
species has been seen having "widespread suc-
cess" with subtraction, scientists announced last

Rhesus macaques placed in front of touch screens
in a Duke University laboratory were able to sub-
tract dots-not by counting them individually but
by using a more instantaneous ability researchers
call number sense.

In each session a monkey was presented with a
number of dots.

Next, a large square would hide all the dots.

Then some of the dots would glide off the screen
from "behind" the shape.

Only the big square, with the remaining dots "hid-
den" behind it, would be left on screen, as seen in
this two-second video:

[see article for video]

Finally, decision time: Two groups of dots would
appear on screen-one of them the correct number
of remaining dots-and the monkey would indicate
its answer to the math problem by touching one of
the groups (see picture of monkey making selec-

Each correct answer was worth a serving of Kool-Aid.

(Related: "Lemur Logic May Provide Clues to Primate
Intellect Evolution.")

Monkeys Subtract as Well as College Students?

In the vast majority of trials, the monkeys chose the
right answer without counting, said psychologist
Jessica Cantlon, who co-led the studies at Duke.

In fact, college students used as controls in the study
had the same success rate as the macaques-each
group choosing the correct answer in as little as a
second ...

A 2007 study co-authored by Cantlon proved mon-
keys' success with addition-again on par with col-
lege students performing the same tasks.

Wild Subtraction

Animals' knack for numbers can boost survival in
the wild, Cantlon told National Geographic News.

For instance, research has shown that apes can
determine at a glance roughly how much food is
present in an area and decide whether to stay and
eat or to move on, she said.

On the 200th anniversary of Charles Darwin's birth,
"these studies suggest we humans should keep our
egos in check," said Edward Wasserman, an exper-
imental psychologist at the University of Iowa.

"We are certainly not the only intelligent animals on

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VIDEO: Chimp Memory Beats Humans'

Watch young chimpanzees beat Japanese
college students in a short-term-memory
test by a wide margin-raising questions
about primate intelligence and evolution.
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Some other articles of interest regarding non-
human intelligence:

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July 3, 2003

Deep thinkers

The more we study dolphins, the brighter they
turn out to be.

by Anuschka de Rohan
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June 6, 2006

Crows Have Human-Like
Intelligence, Author Says

by John Roach
for National Geographic News
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Aug 14th 2008

Primate intelligence

Out of the mist

From The Economist print edition

Is Rollie an exception, or are
all gorillas as clever?
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Primate Intelligence

Primate Communication

The Origins of Primates

Humans and Other Primates
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June 05, 2008

Elephant Intelligence: Why Elephants
Might Be as Smart as Humans

by Esther November
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Elephant Intelligence
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October 8, 2008

The Intelligence of Animals
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July 21, 2006. 3:07pm (AEST)

Parrots 'as intelligent' as young children

by Kirsten Veness for The World Today
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