source Economist.com
THE last time Irene Pepperberg saw Alex she said goodnight as usual.
“You be good,” said Alex. “I love you.” “I love you, too.” “You'll be
in tomorrow?” “Yes, I'll be in tomorrow.” But Alex (his name supposedly
an acronym of Avian Learning Experiment) died in his cage that night,
bringing to an end a life spent learning complex tasks that, it had
been originally thought, only primates could master.
In science as in most fields of endeavour, it is important to have
the right tool for the job. Early studies of linguistic ability in apes
concluded it was virtually non-existent. But researchers had made the
elementary error of trying to teach their anthropoid subjects to speak.
Chimpanzee vocal cords are simply not up to this—and it was not until
someone had the idea of teaching chimps sign language that any progress
was made.
Even then, the researchers remained human-centric. Their assumption
was that chimps might be able to understand and use human sign language
because they are humanity's nearest living relatives. It took a
brilliant insight to turn this human-centricity on its head and look at
the capabilities of a species only distantly related to humanity, but
which can, nevertheless, speak the words people speak: a parrot.
The insight in question came to Dr Pepperberg, then a 28-year-old
theoretical chemist, in 1977. To follow it up, she bought a
one-year-old African Grey parrot at random from a pet shop. Thus began
one of the best-known double acts in the field of animal-behaviour
science.
Dr Pepperberg and Alex last shared a common ancestor more than 300m
years ago. But Alex, unlike any chimpanzee (with whom Dr Pepperberg's
most recent common ancestor lived a mere 4m years ago), learned to
speak words easily. The question was, was Alex merely parroting Dr
Pepperberg? Or would that pejorative term have to be redefined? Do
parrots actually understand what they are saying?
Bird brained
Dr Pepperberg's reason for suspecting that they might—and thus her
second reason for picking a parrot—was that in the mid-1970s
evolutionary explanations for behaviour were coming back into vogue. A
British researcher called Nicholas Humphrey had proposed that
intelligence evolves in response to the social environment rather than
the natural one. The more complex the society an animal lives in, the
more wits it needs to prosper.
The reason why primates are intelligent, according to Dr Humphrey,
is that they generally live in groups. And, just as group living
promotes intelligence, so intelligence allows larger groups to
function, providing a spur for the evolution of yet more intelligence.
If Dr Humphrey is right, only social animals can be intelligent—and so
far he has been borne out.
Flocks of, say, starlings or herds of wildebeest do not count as
real societies. They are just protective agglomerations in which
individuals do not have complex social relations with each other. But
parrots such as Alex live in societies in the wild, in the way that
monkeys and apes do, and thus Dr Pepperberg reasoned, Alex might have
evolved advanced cognitive abilities. Also like primates, parrots live
long enough to make the time-consuming process of learning worthwhile.
Combined with his ability to speak (or at least “vocalise”) words, Alex
looked a promising experimental subject.
And so it proved. Using a training technique now employed on
children with learning difficulties, in which two adults handle and
discuss an object, sometimes making deliberate mistakes, Dr Pepperberg
and her collaborators at the University of Arizona began teaching Alex
how to describe things, how to make his desires known and even how to
ask questions.
By the end, said Dr Pepperberg, Alex had the intelligence of a
five-year-old child and had not reached his full potential. He had a
vocabulary of 150 words. He knew the names of 50 objects and could, in
addition, describe their colours, shapes and the materials they were
made from. He could answer questions about objects' properties, even
when he had not seen that particular combination of properties before.
He could ask for things—and would reject a proffered item and ask again
if it was not what he wanted. He understood, and could discuss, the
concepts of “bigger”, “smaller”, “same” and “different”. And he could
count up to six, including the number zero (and was grappling with the
concept of “seven” when he died). He even knew when and how to
apologise if he annoyed Dr Pepperberg or her collaborators.
And the fact that there were a lot of collaborators, even strangers,
involved in the project was crucial. Researchers in this area live in
perpetual fear of the “Clever Hans” effect. This is named after a horse
that seemed to count, but was actually reacting to unconscious cues
from his trainer. Alex would talk to and perform for anyone, not just
Dr Pepperberg.
There are still a few researchers who think Alex's skills were the
result of rote learning rather than abstract thought. Alex, though,
convinced most in the field that birds as well as mammals can evolve
complex and sophisticated cognition, and communicate the results to
others. A shame, then, that he is now, in the words of Monty Python, an
ex-parrot.
Alex the African Drey - Science's best known parrot died on September 6th, aged 31
source Economist.com
Sep 20th 2007
HemuZ Nature
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