The #1 source for news about monkeys and apes

[Natasha Matza <natasha_primatesanctuary AT yahoo.com>]

Gorillas take stab at mind games
Lincoln Park Zoo tests primates' use of tools and
finds that history of cognitive power may be longer
than believed

By William Mullen
Tribune staff reporter
Published October 30, 2005

When reports came out of Africa in recent weeks that
researchers for the first time in history were seeing
wild gorillas using sticks and rocks as tools, keepers
at Lincoln Park Zoo weren't exactly surprised.

Earlier this year, zoo researchers watched two female
gorillas figure out how to use sticks to retrieve two
of their favorite snack foods--ketchup and
mustard--from holes in a fake termite mound. It took
weeks, but the apes finally learned that if they
inserted a stick of the right length into the holes,
the stick would come out coated with a slurpable
treat.

Already they had watched as zoo gorillas tackled "food
puzzles," or lengths of PVC pipe sealed at each end,
pierced with holes and stuffed with raisins or peanut
butter. Sometimes the apes shook treats out of the
holes, but other times they seemed to use sticks to
dig at the food, a behavior that could be construed as
tool use.

"We had seen our gorillas do this, as had keepers at
other zoos, but because gorillas aren't known to be
tool users in the wild, it was thought this knowledge
of captive gorillas using them was not applicable,"
said Elizabeth Lonsdorf, the zoo's director of
conservation resources.

But in late September, field researchers in the
Republic of Congo reported they had seen a female
lowland gorilla use long sticks to gauge water depth
while walking through a swamp pond. A different female
selected and laid down a dead tree trunk to cross a
deep swamp patch.

Other researchers at a lowland gorilla sanctuary in
Congo reported earlier this month on an orphaned, 2
1/2-year-old female gorilla who smashes palm nuts
between rocks to extract oil--an even more complex
behavior known as the "hammer and anvil" technique.

This proof that tool use is a natural behavior for
gorillas represents a surprisingly profound discovery.
Previously it was thought humans and chimpanzees were
the only primates that have the cognitive powers
needed to fashion and use tools to accomplish certain
tasks. Seeing gorillas use tools indicates that
cognitive power probably occurred far earlier in
history than previously thought, when all the great
apes had a common ancestor.

It also points up the irony, said Lonsdorf that only
in the recent past has science begun to study man's
closest genetic relatives--gorillas, chimps and
orangutans--just when human activity has wild apes on
a fast path to extinction.

"Before we really get to know and understand their
lives in the wilderness, they could be gone," Lonsdorf
said.

Lonsdorf said it doesn't surprise her that scientists
are only now observing tool use by gorillas in the
wild.

"Most of what we know about wild gorillas is from a
very small population of mountain gorillas, who live
in an atypical environment for their species,"
Lonsdorf said. "Mountain gorillas live in a salad
bowl, feeding on a relatively narrow selection of
easily obtainable fruits and leaves that they have no
trouble finding or eating."

For that reason, they have little incentive to develop
tools.

With fewer than 700 mountain gorillas left, zoos keep
and breed only lowland gorillas. Though more numerous
than their mountain cousins, far less is known about
lowland gorillas in the wild because they live in
heavily forested, swampy terrain where it is difficult
to find them and even harder to follow them for
observation.

As big logging companies have begun clear-cutting
their forests in recent years, however, scientists
have increased efforts to get in the swamps and learn
about them in hopes of slowing the wholesale
destruction of their world. The discovery of the two
females using tools in the swamp in the Republic of
Congo grew out of those efforts.

Soon after Lincoln Park moved its resident troops of
lowland gorillas and chimpanzees into the zoo's new
apehouse in July 2004, Lonsdorf and her colleagues
started a comparative study of tool use between
gorillas and chimps.

One of the ape habitats in the building is equipped
with a fake termite mound. Because it is built flush
to a viewing window, the public can see into the
mound's hollow interior.

That is where keepers can attach tubes filled with
mustard or ketchup to small holes that are open to the
apes and allow them to smell the treats.

Keepers leave sticks and straw of varying lengths near
the mound, but it is up to the apes to decide to pick
up a stick or stem and try to insert it into a hole.
If the stick is long enough, it will come out coated
with the condiment.

Quick learners

The experiment started with a troop of chimps known as
Hank's group after one of its male leaders. In the
wild, chimps learn from their mothers to "fish" for
termites to eat by carefully poking sticks and straw
into termite mound holes.

"The chimps caught on the very first day," said
Lonsdorf, "at least the female chimps did. From then
on ... they would get so excited when they heard
keepers inside the termite mound, they were sticking
their sticks through the hole before the mustard tubes
were attached. It got so I worried they'd poke a
keeper's eye out."

The male chimps weren't so quick to pick up on the
technique, she said, which also is the case in the
wild.

"One little male in Hank's group tried it
unsuccessfully," she said, and other young males
didn't try at all. "It took Hank four weeks to catch
on."

Last January, keepers moved Hank's group out and
brought in a gorilla group headed by JoJo, a
silverback. Unlike the chimps, JoJo's family had
frequently played with the PVC pipe food puzzles in
the past.

"We baited our termite holes at random times between
11 a.m. and 2 p.m., sometimes two days a week,
sometimes three," said Lonsdorf. "We don't want them
to become accustomed to it through routine."

The gorillas, especially the adult females, quickly
noticed something was happening when they heard the
keepers inside the mound after two weeks of no treats.
Ignoring the sticks under their feet, they'd spend 15
or 20 minutes trying fruitlessly to stick their
fingers into the holes before losing interest.

"It took almost two months before any of the gorillas
figured it out," Lonsdorf said. The two adult females,
Makari, 18, and Bahati, 15, were the ones who
succeeded.

No other gorillas ever learned to use the sticks.

Early in September, keepers switched Hank's group back
in. As the research continues, JoJo's family likely
will be returned to the habitat at some point next
year to see if more gorillas learn how to use the
sticks.

"It's a good situation for comparative studies in
which the chimps and gorillas are given the
opportunity to do the same tasks in the same
environment," Lonsdorf said.

New experiment

She and the zoo's chief animal behaviorist, Steve
Ross, already are trying to devise a second tool
experiment, providing hard-shelled nuts to the apes
and a hammer-like object to break them open.

The trick for the scientists is to figure out how they
can add a big rock to the exhibit that is anchored
with an unbreakable chain or cable so it can't be
carried away by the animals.

"Obviously we can't leave a big boulder in there,"
said Lonsdorf, "because JoJo or Hank might try tossing
it through a window."

natasha_primatesanctuary AT yahoo.com
www.primatesanctuary.blogspot.com
www.primatesanctuary.org


                
__________________________________ 
Yahoo! FareChase: Search multiple travel sites in one
click.
http://farechase.yahoo.com


                
__________________________________ 
Yahoo! FareChase: Search multiple travel sites in one click.
http://farechase.yahoo.com