1. Sheep Can Remember Faces for a Long Time
In 2001, researchers at a laboratory in Cambridge, England, including Keith Kendrick, published a study titled "Sheep don't forget a face." [1] They taught 20 sheep to choose between photos of other sheep, rewarding them with food for correct choices. The sheep continued to choose correctly not only from frontal views but also from side profiles. [1]
Can they recognize famous people? The study found that sheep could remember the faces of up to 50 other sheep and one familiar human for at least 2 years. [1] In 2017, researchers from the same university conducted an experiment with 8 sheep. They showed the sheep photos of four celebrities they had never seen before. The sheep selected the correct frontal face photos with an accuracy rate of about 80%. [2]
2. Archerfish Can Tell Human Faces Apart
It might seem surprising to hear that fish can distinguish human faces. In 2016, a research team from the UK and Australia tested archerfish, a species known for spitting water to knock insects off leaves. [3] The experiment aimed to see if these fish could recognize human faces.
After teaching a fish to recognize one specific face photo, researchers presented it with that face alongside photos of 44 unfamiliar people. The archerfish chose the memorized face by spitting water at it with an average accuracy rate of 81%. [3] This discovery is significant because fish lack the neocortex, the part of the brain that is said to be used by humans and mammals when distinguishing faces. Yet, through learning, they were still able to tell faces apart. [3]
3. Paper Wasps Recognize the Faces of Other Wasps
Recognizing faces is not limited to animals with backbones. In 2002, American biologist Elizabeth Tibbetts discovered that a species of paper wasp identifies individual members by the patterns on their faces. [4] These wasps have yellow facial markings that can differ from one individual to another.
Tibbetts painted over the facial patterns of a familiar wasp and returned it to the nest. The other wasps attacked the individual with the changed appearance more aggressively than before. [4] These wasps form a society where food and work are decided by a hierarchy of strength. [4]
4. Why Different Animals Can All Recognize Faces
Sheep, archerfish, and paper wasps belong to completely different groups of living things. However, they share a common trait: they are social creatures that form groups with their kind or maintain relationships with specific partners.
Being able to distinguish faces (or face-like marks) allows them to make judgments like "I have met this individual before" or "I should be careful with this one." It is thought that the ability to distinguish faces developed separately in these creatures, despite their vastly different brain sizes and evolutionary paths.
5. How to Test Face Recognition in Animals Near You
If you are interested, try observing animals close to you. If you have a pet, observe whether it distinguishes the faces of family members. Compare how its vocalizations or tail wagging changes depending on the person. In a park, watch how pigeons or sparrows flee from people. Quietly observe if their escape behavior differs between those who always feed them and those who do not.
It is helpful to write down something that caught your attention. This serves as an entry point for further research. For example, asking "How does an archerfish spit water?" is enough to start looking into the details. [3]