Stephen CWLL asked:
How well can animals tell each other apart?
We put Steven's question to Naked Scientist Georgia Mills.
Georgia - With animals, it really depends on the animal. There are so many of them, but if there is a need for an animal to tell individuals apart then itís likely that this will evolve. So, for example, animals that work together in groups. I think itís been shown that wasps actually have really good facial recognition.
Chris - As in for humans.
Georgia - No, of other wasps. I guess thatís a study to come of whether wasps can tell people apart. But another example is in cooperative breeding. So, that's when a male and a female team up to bring up their young. It really helps if you can remember who your partner is in this kind of situation. So, birds have calls to recognise each other. For example, penguins, when they meet up. When it comes to telling humans apart, thatís less useful for most animals. I think dogs, theyíve been selected over many years to live among humans. So, they're actually quite good at telling us apart by our smell and also by our faces. But for most animals, itís not really beneficial to be able to tell different people apart.
Chris - I did read a study a few years ago now. There were some researchers who did some experiments on mocking birds. They found that if they went to these mocking bird nests and aggravated the birds just to annoy them a little bit, the first time they did it, the birds werenít terribly alarmed. The second time the person did it, the birds knew what was coming and they mounted a sort of response to sort of frighten the person away from their nest. The third time they did, they nearly attack the guy. Then as an experiment, the researchers sent in another member of the research group who hadnít been near the nest and hadnít been seen by the birds before. She approached the nest and got the same reaction that the guy did the first time he went in, proving that they can tell people apart. So, they obviously do have quite a good ability to discriminate between individuals and I suppose they are very seeing creatures arenít they I mean Max, they're very good at seeing, the birds have excellent vision, donít they?
Max - Yeah, they do. They have much better eyesight than we do. Instead of the three cones that we have, most birds have four and can see all the way into the UV spectrum as well, into ultraviolet light.
Chris - When you say the cones, these are the cells at the back of the eye that convert light into brain activity.
Max - Exactly that.