Every year my research group take a trip together, and this year we decided to travel to the Cleveland Metroparks Zoo. I hadn’t visited this zoo since I was a teenager, so I was really looking forward to it.
The Cleveland Zoo has been in its current location for over 100 years, and boasts one of the most diverse collections of primates in North America. Fortunately, I work in Kent State’s Anthropology Department, and many of the people I was traveling with are primate experts. This meant, of course, that the primate exhibits ranked #1 on our list of things to see.
It was strikingly apparent, however, that despite the enthusiasm of the other visitors, most of them had real trouble identifying even the most basic differences among primates.
For example, I saw one child watching an animal climb a tree and heard him ask if it was a squirrel. This was a forgivable mistake, since he was around 4 years old, and the animal in question was about the size of a large squirrel. However, what really struck me was his mother’s reply. “No, it’s just a monkey,” she said dismissively, despite the fact that display was clearly labeled Mongoose Lemur (Lemur mongoz).
I understand that the average person is not an expert in primate taxonomy. But this mother would have never told her child that a that a lion was a cheetah, or even a tiger. Despite their superficial similarities, it is obvious that these animals are fundamentally distinct. Parents know that even young children are capable of telling them apart. People don’t use their names interchangeably simply because they are both big cats. So why is it acceptable to use the name “monkey” for all primates?
Lets take a look at when these examples actually diverged from each other. Lions, cheetahs, and tigers all belong to the family Felidae, which first arose about 25 million years ago. According to the Time Tree of Life, a website that gives approximate divergence times for various groups of organisms, lions (Panthera leo) and cheetahs (Acinonyx jubatus) diverged about 9.4 million years ago. Lions and tigers (Panthera tigris) are actually two species in the same genus, and only diverged about 3.7 million years ago. In fact, lions and tigers are so closely related that they can even form hybrids, know as a liger (if the male is a lion) or tigon (if the male is a tiger). Yet these two species of cat are almost never confused.
Lemurs, on the other hand, are drastically different from other primates. They are classified as a suborder of primates called strepsirrhini, which forms its own branch of the primate family tree. Lemurs diverged from other primates around 77.4 million years ago, and began evolving separately when they became geographically isolated on the island of Madagascar. The other major lineage of primates is the haplorhines, which includes platyrrhines (New World Monkeys) and catarrhines (Old World Monkeys and Apes).
As you can see in the figure above, the word “monkey” doesn’t refer to a single group of animals. All monkeys share a common ancestor, but that ancestor gave rise to more than just monkeys. Evolutionary biologists describe this type of pattern as being “paraphyletic.”
Later that day, I was taking this photograph of a flanged adult male orangutan when I overheard a child ask if these were the chimpanzees. “No,” her dad replied, “chimps are monkeys.”
Now, I know that lemurs are not the most well-known primates. In fact, the only famous lemur I can think of is King Julien XIII, the ring-tailed lemur voiced by Sacha Baron Cohen in the Dreamworks movie Madagascar. But that excuse goes right out the window when you begin talking about apes. Apes are by far the most well-known primate group – you literally see them every day!
I’m not the only one that feels this way. Anthropologist Holly Dunsworth recently recounted some of her negative experiences attempting to educate zoo visitors on the differences between apes and monkeys:
Apes are gibbons, siamangs, orangutans, gorillas, chimps, and people. We apes don’t have tails and we have big brains and advanced cognitive skills among other traits. Monkeys have tails (even ones that look tailless have little stubs) and most have much smaller brains (an exception being the capuchin).
Apes and monkeys are separate categories of animals. This is why calling an ape a monkey sounds absolutely crazy and that is why some people just can’t help themselves and morph into prickish pedants around ignorant zoo visitors.
So the next time you visit a zoo, please remember: not all primates are monkeys!