Honey Bees Can Recognize Human Faces!

A World Science news item dated December 9, 2005 reports Adrian Dyer's study published in Journal of Experimental Biology

Scientists used to believe that facial recognition required a large brain. Adrian G. Dyer of the Johannes Gutenberg University in Mainz, Germany, a leading scientist in the field feels that this may not be the case. He found in his study on honey bees that even with a smaller brain than that of the humans, they could recognize human faces. According to Dyer the finding is the first time an invertebrate has shown ability to recognize faces of other species.

In their study, Dyer and two colleagues presented honey bees 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. They tried to train the bees to realize that a photo of one man had a drop of sugary liquid next to it. Other photos had a drop of a bitter liquid. Five of the several bees trained in this way "learned to fly toward the photo horizontally in such a way that they could get a good look at it. In fact, these bees tended to hover a few centimeters in front of the image for a while before deciding where to land." Some "bees apparently failed to realize that they should pay attention to the photos at all."

The World Science report says that "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." “Two bees tested two days after the initial training retained the information in long-term memory,” the scientists 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 World Science report adds: "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). 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 hive mates. But the new study shows that they can recognize human faces better than some humans can—with one-ten thousandth of the brain cells."
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