May 18, 2006
Some apes, birds can think ahead, studies show
By Maggie Fox, Health and Science Correspondent
WASHINGTON (Reuters) - Apes that remember to carry the
right tools to retrieve treats and scrub jays that hide food a
second time when they think a rival is watching prove animals
can think ahead -- a trait once believed to be uniquely human,
scientists have found.
on Friday in the journal Science show intelligent birds and
great apes can plan into the future in a way that transcends
simple food caching, as squirrels, foxes and other animals do.
"Planning for future needs is not uniquely human," Thomas
Suddendorf of the University of Queensland in Brisbane,
Australia, wrote in a commentary.
"Apes and jays can also anticipate future needs by
remembering past events, contradicting the notion that such
cognitive behavior only emerged in hominids."
In one experiment, Nicholas Mulcahy and Josep Call of the
Max Planck Institute for Evolutionary Anthropology in Leipzig,
Germany, tested bonobos, close relatives of chimpanzees, and
orangutans at the local zoo.
They set up several experiments that required the apes to
remember a complex way to retrieve a treat and offered them the
opportunity to use tools to do so.
So far, observations of tool use and planning have involved
only immediate hunger on the part of the animals, which does
not involve long-term thinking, Mulcahy and Call argued.
"Thus, when chimpanzees transport stones to use them to
crack open nuts, or New Caledonian crows make hook-shaped tools
to fish for insects, they do so in an attempt to satisfy their
current hunger state, not some future one," they wrote.
In one experiment, they rigged up a metal cylinder with a
piece of uncooked spaghetti holding two bunches of grapes.
"To obtain the reward subjects had to break the spaghetti
by inserting a plastic tube through the top hole over the
cylinder. That caused the grapes to fall down and hang in front
of the bottom holes thus allowing subjects access to them," the
In another test, the apes had to use a metal hook to fish
out a bottle of grape juice.
To pass the tests, the apes had to remember to bring the
right tool out of the room with them, and bring it back with
them some time later. Both orangutans and bonobos passed the
tests several times, the researchers said.
'NOT A UNIQUELY HUMAN ABILITY'
"Together with recent evidence from scrub jays, our results
suggest that future planning is not a uniquely human ability,
thus contradicting the notion that it emerged in hominids only
within the past 2.5 to 1.6 million years," Mulcahy and Call
Joanna Dally of the University of Cambridge in Britain and
colleagues tested captive scrub jays, and saw the birds could
remember which other birds were watching them when they first
hid some treats.
If a bird dominant to the jays saw them store their food,
the jays would move the cache later when the dominant bird was
But if the bird allowed to watch the treat being hidden was
subordinate, or a mate, the jays did not later re-cache their
food -- presumably because they could fight off subordinates
that try to steal their food, the researchers wrote.
"These results suggest scrub-jays remember who observed
them make specific caches," Dally's team wrote.
Jays are members of a group of birds called corvids, which
include crows, jays and ravens and which biologists consider to
be the most intelligent species of bird.