It's always a pleasure to pick a friendly face out of a sea of strangers. In fact the ability to recognise a face was believed to single out mammals,with their advanced brains, from other simpler species. How we recognise faces has been hotly debated for at least three decades. Adrian Dyer explains it has been thought that we have specialised brain regions dedicated to facial recognition, but there is currently no conclusive evidence to support this idea. However, a big brain does seem to be the most important asset for facial recognition. Or is it...? It occurred to Dyer that he could test whether a big brain was a prerequisite for facial recognition by trying to find out if insects with tiny brains could also recognise human faces. While working in Christa Neumeyer's lab in Johannes Gutenberg Universität, Germany, Dyer decided to put bee's legendary pattern recognition skills to the test to see whether they could learn to recognise a human face(p. 4709).

Training bees to do such an experiment is far from straight forward. First,you have to focus the bees' attention on the task in hand. Dyer explains that he started out offering the bees a tasty sugar reward whenever they visited the picture of a face they were learning to recognise. But after days of training, Dyer was beginning to despair that the bees would ever get the point; they were still flying in fast and visiting face pictures at random,until he thought of attracting the bees to a spoonful of sugar solution and taking them directly to the picture he wanted them to commit to memory. The bees finally got the point and began studying their subject more closely,flying in slowly and considering the pictures before homing in on their subject and retrieving the reward.

Having caught the insect's eye Dyer was ready to start the painstaking training process, but bees are wily creatures; Dyer knew he had to be sure that the bees had learned to recognise a face rather than using other cues to direct them to their sweet treat. By rearranging the faces on the board Dyer convinced himself that the bees weren't using positional cues. Finally he removed the sugar reward, and offered the bees a choice between two faces; the one they'd been trained to recognise and another face they'd been trained to avoid. The bees continued returning to visit the face they had been trained to recognise. Dyer remembers that it was the end of a long day when he finally realised that bees had learned to distinguish a human face from other faces and that he was so amazed that he called Neumeyer telling her to come quickly because `no one's going to believe it; and bring a camera!'

Once he was sure the bees could distinguish between faces, Dyer needed to go a step further; could the bees pick out a familiar face from a crowd of strangers? Dyer presented the bees with a choice; the familiar face they had been trained to recognise and a stranger's face they had never seen before. If the bees went straight to the familiar face it must recognise it. Amazingly,the bees kept returning to the familiar face. Even though they have less than 1 million neurons in their brains, bees can still recognize human faces.

References

References
Dyer, A. G., Neumeyer, C. and Chittka, L.(
2005
). Honeybee (Apis mellifera) vision can discriminate between and recognise images of human faces.
J. Exp. Biol.
208
,
4709
-4714.