Constructive social interaction depends upon recognizing those one is interacting with. Not surprisingly, then, we have a section of our cortex devoted to facial recognition. But we're not the only ones.
Keith Kendrick has shown that "individual sheep can remember 50 other different sheep faces for over 2 years." He did this by training sheep to find food in Y-shaped passages containing pictures of other sheep.
Even common paper wasps (Polistes fuscatus) with miniscule brains can recognize the faces of fellow wasps. Closely related Polistes metricus wasps, however, show no such ability.
What's the difference?
Polistes fuscatus wasps live in colonies with multiple queens and a social hierarchy. However, with Polistes metricus wasps, there's only one queen per colony; since the wasps in such Polistes metricus colonies are all closely related, there's no inter-nest politics and therefore no need to distinguish one wasp from another.
All of which explains why politicians are said to never forget a face.
- "Face Smarts" by Susan Milius, Science News October 6, 2012
- "Sheep don't forget a face", by Keith M. Kendrick1, Ana P. da Costa1, Andrea E. Leigh1, Michael R. Hinton1 & Jon W. Peirce1, in Nature 414, 165-166 (8 November 2001)
- "Specialized Face Learning Is Associated with Individual Recognition in Paper Wasps", by Michael J. Sheehan & Elizabeth A. Tibbetts, Science 2 December 2011: Vol. 334 no. 6060 pages 1272-1275