[Paleopsych] World Science: Bees can recognize human faces, study finds
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Mon Jan 2 20:57:45 UTC 2006
Bees can recognize human faces, study finds
Honeybees may look pretty much all alike to us.
But it seems we may not look all alike to them. A
study has found that they can learn to recognize
human faces in photos, and remember them for at least two days.
The findings toss new uncertainty into a
long-studied question that some scientists
considered largely settled, the researchers say:
how humans themselves recognize faces.
The results also may help lead to better
face-recognition software, developed through
study of the insect brain, the scientists added.
Many researchers traditionally believed facial
recognition required a large brain, and possibly
a specialized area of that organ dedicated to
processing face information. The bee finding
casts doubt on that, said Adrian G. Dyer, the lead researcher in the study.
He recalls that when he made the discovery, it
startled him so much that he called out to a
colleague, telling her to come quickly because
?no one?s going to believe it?and bring a camera!?
Dyer said that to his knowledge, the finding is
the first time an invertebrate has shown ability
to recognize faces of other species. But not all
bees were up to the task: some flunked it, he
said, although this seemed due more to a failure
to grasp how the experiment worked than to poor
facial recognition specifically.
In any cases, some humans also can?t recognize
faces, Dyer noted; the condition is called prosopagnosia.
In the bee study, reported in the Dec. 15 issue
of the Journal of Experimental Biology, Dyer and
two colleagues presented honeybees with photos of
human faces taken from a standard human
psychology test. The photos had similar lighting,
background colors and sizes and included only the
face and neck to avoid having the insects make
judgments based on the clothing. In some cases,
the people in the pictures themselves looked similar.
The researchers, with Johannes Gutenberg
University in Mainz, Germany, tried to train the
bees to realize that a photo of one man had a
drop of a sugary liquid next to it. Different
photos came with a drop of bitter liquid instead.
A few bees apparently failed to realize that they
should pay attention to the photos at all. But
five bees learned to fly toward the photo
horizontally in such a way that they could get a
good look at it, Dyer reported. In fact, these
bees tended to hover a few centimeters in front
of the image for a while before deciding where to land.
The bees learned to distinguish the correct face
from the wrong one with better than 80 percent
accuracy, even when the faces were similar, and
regardless of where the photos were placed, the
researchers found. Also, just like humans, the
bees performed worse when the faces were flipped upside-down.
?This is evidence that face recognition requires
neither a specialised neuronal [brain] circuitry
nor a fundamentally advanced nervous system,? the
researchers wrote, noting that the test they used
was one for which even humans have some difficulty.
Moreover, ?Two bees tested two days after the
initial training retained the information in
long-term memory,? they wrote. One scored about
94 percent on the first day and 79 percent two
days later; the second bee?s score dropped from
about 87 to 76 percent during the same time frame.
The researchers also checked whether bees
performed better for faces that humans judged as
being more different. This seemed to be the case,
they found, but the result didn?t reach statistical significance.
The bees probably don?t understand what a human
face is, Dyer said in an email. ?To the bees the
faces were spatial patterns (or strange looking flowers),? he added.
Bees are famous for their pattern-recognition
abilities, which scientists believe evolved in
order to discriminate among flowers. As social
insects, they can also tell apart their
hivemates. But the new study shows that they can
recognize human faces better than some humans
can?with one-ten thousandth of the brain cells.
This raises the question of how bees recognize
faces, and if so, whether they do it differently
from the way we do it, Dyer and colleagues wrote.
Studies suggest small children recognize faces by
picking out specific features that are easy to
recognize, whereas adults see the
interrelationships among facial features. Bees
seem to show aspects of both strategies depending
on the study, the researchers added.
The findings cast doubt on the belief among some
researchers that the human brain has a
specialized area for face recognition, Dyer and colleagues said.
Neuroscientists point to an area called the
fusiform gyrus, which tends to show increased
activity during face-viewing, as serving this
purpose. But the bee finding suggests ?the human
brain may not need to have a visual area specific
for the recognition of faces,? Dyer and colleagues wrote.
That may be helpful to researchers who develop
face-recognition technologies to be used for
security at airports and other locations, Dyer
noted. The United States is investing heavily in
such systems, but they still make many mistakes.
Already, the way that bees navigate is being used
to design ?autonomous aircraft that can fly in
remote areas without the need for radio contact
or satellite navigation,? Dyer wrote in the
email. ?We show that the miniature brain can
definitely recognize faces, and if in the future
we can work out the mechanisms by which this is
achieved,? this might suggest ideas for improved face recognition technologies.
Dyer said that if bees can learn to recognize
humans in photos, then they reasonably might also
be able to recognize real-life faces. On the
other hand, he remarked, this probably isn?t the
explanation for an adage popular in some parts of
the world?that you shouldn?t kill a bee because
its nestmates will remember and come after you.
Francis Ratnieks of Sheffield University in
Sheffield, U.K., says that apparent bee revenge
attacks of this sort actually occur because a
torn-off stinger releases chemicals that signal
alarm to nearby hivemates. Says Dyer, ?bees don?t
normally go around looking at faces.?
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