Evolution psychologists such as Carl Sagan in his book Demon Haunted World have linked Pareidolia to a survival technique, an evolutionary advantage which benefited our ancestors. He wrote that infants who were unable able to recognise faces were less likely to be loved by their parents.
Assuming there are faces in your environment also meant that our ancestors were safer from predators. An example of this was given by Christopher French of the British Psychological Society. He said:
"A classic example is the Stone Age guy standing there, scratching his beard, wondering whether that rustling in the bushes really is a sabre-toothed tiger. You're much more likely to survive if you assume it's a sabre-toothed tiger and get the hell out of there - otherwise you may end up as lunch."
With facial recognition software, computers are now able to see faces too and often make mistakes. This can be seen to be similar to pareidolia.