But now, a relatively small study from University of Cambridge scientists shows that sheep might be joining that club.
Humans and monkeys can now extend a warm welcome to sheep for joining us in being able to recognize human faces from photographs.
Morton and her team are now studying sheep that have been genetically modified to carry the gene mutation that causes Huntington's disease.
As with some other animals such as dogs and monkeys, sheep are social animals and can recognise other sheep as well as familiar humans. The sheep were having two options in each step as a photo of celebrity face or another is of something else.
For the initial training, the sheep received a food reward for choosing the face versus a blank screen.
The sheep made the correct choice of celebrity or handler roughly 70 percent of the time on average.
The research isn't just a silly test, though. Then, during the trials, the sheep were released into a pen where they had to discern between the familiar faces and an object or an unfamiliar face.
The sheep were able to pick out the celebrities and earn the food reward 8 out of 10 times. On her first try, one sheep appeared taken aback by the new face in the mix.
To challenge the sheep even further, scientists showed them the same celebrities in photos captured from a different, tilted angle.
Brad Duchaine, a brain scientist at Dartmouth College, doesn't find the sheep's ability surprising.
The animals' success rate fell by around 15 per cent when presented with the faces at a new angle, an amount researchers said was comparable to that seen when humans perform the task.
In addition, they also say the study could help in the research into Huntington's disease, as well as other human brain disorders that affect mental processing.
Sheep are known for their sociability, but this showed - with some training - the sheep could not only recognize fellow sheep and humans they knew, but process images of faces.