Researcher’s at Canada’s Wilfrid Laurier University have stated that they have created a generation of fruit flies that can “count.” Populations were exposed to two, three or four flashes of light, with their container being shaken at Flash 2 and 4. Soon after, they were put into the same situation. 39 generations showed no response to the flashes, but the 40th had a number of flies who braced themselves after Flash 2 in expectation of a shake.
A fascinating study, one demonstrating the ancient roots of numbering. The fact that it only took 40 generations (an astonishingly small number for such a specific ability) to find flies capable of recognizing numbers implies that it might not be terribly uncommon an occurrence.
It should be noted that while it is possibly evolution (the changing of genetic material over time), it is not a case of natural selection. The scientists did not take out flies from previous generations who might have had some counting ability and breed specifically from them.