Curious baby monkeys in Lopburi, Thailand.
Curious baby monkeys in Lopburi, Thailand. (Photo: jeep2499 /Shutterstock)

Considering they're one of our closest cousins, you'd think we humans would know a thing or two about monkeys. However, there's a surprising number of misconceptions and myths that continue to circulate about these clever primates. Let's all take a moment to brush up on these 11 eye-opening facts about these fascinating creatures.

1. Apes and lemurs are not monkeys

A chimpanzee, a Javan lutung and a ring-tailed lemur.
A chimpanzee, a Javan lutung and a ring-tailed lemur. (Photo: Kjersti Joergensen/Marek Velechovsky/Eric Gevaert/Shutterstock)

The term "monkey" is sometimes used as a catch-all for every animal in the primate family, but the truth is that monkeys live on completely different branches of the evolutionary tree from both apes (i.e. chimpanzees, gorillas and humans) and prosimians (i.e. lemurs, tarsiers and lorises). If you're not sure if you're looking at a monkey or an ape, keep an eye out for these telltale traits.

2. Human industry threatens many of the world's monkeys

Gray-shanked douc langurs are one of the world's most critically endangered primates.
Gray-shanked douc langurs are one of the world's most critically endangered primates. (Photo: grass-lifeisgood/Shutterstock)

Some of the most fascinating monkey species are experiencing rapid declines in population due to a variety of factors based on their unique location. These factors include everything from habitat loss and fragmentation, live capture for the global pet trade, and hunting for bushmeat or traditional medicines.

Just a few of the monkeys that are on the IUCN's list of the 25 most endangered primates year after year include the grey-shanked douc langur (pictured above), the Tonkin snub-nosed monkey, the Delacour's langur and the golden-headed langur.

3. There's only one free-living species of wild monkey in Europe

A barbary macaque rests on a ledge in the British Overseas Territory of Gibraltar.
A barbary macaque rests on a ledge in the British Overseas Territory of Gibraltar. (Photo: Anilah/Shutterstock)

Nearly all of the Earth's wild monkeys are confined to just four parts of the world: New World species are found in South and Central America, while Old World species are found in Asia and Africa. There is one exception, though — the thriving population of wild Barbary macaques that roam free in the Iberian island of Gibraltar. DNA analysis shows that these macaques, which have been in Gibraltar for many centuries, originated from Northern Africa.

Although these Barbary macaques are the only wild monkeys currently living in Europe, it's important to note that it wasn't always that way. Prior to the Ice Age, macaques could be found as far north as Germany and the British Isles.

4. Pygmy marmosets are the world's smallest monkeys

Pygmy marmosets are not just tiny — they're downright adorable!
Pygmy marmosets are not just tiny — they're downright adorable! (Photo: bluedogroom/Shutterstock)

Native to the Amazon Basin of South America, this tiny New World monkey weighs in at about 3.5 ounces upon reaching adulthood. Although the pygmy marmoset is the tiniest monkey, the award for the smallest primate goes to the Madame Berthe's mouse lemur.

5. Mandrills are the world's largest monkeys

Mandrills are the world's largest non-ape primates.
Mandrills are the world's largest non-ape primates. (Photo: Abeselom Zerit/Shutterstock)

Mandrills are easily recognizable because of the vibrant coloration of their faces and behinds, but another fascinating aspect of their extreme sexual dimorphism that sets them apart from other monkeys is their immense size. While female mandrills weigh in at around 27 pounds on average, adult male mandrills can weigh up to 82 pounds!

6. The vibrancy of a bald uakari's red face is indicative of its health

A bald uakari with a vibrant red face enjoys a meal.
A bald uakari with a vibrant red face enjoys a meal. (Photo: Steve Cukrov/Shutterstock)

Scientist believe these peculiar New World monkeys evolved with bright red faces in response to malaria, which is prevalent in the Amazon rain forest where they live. Generally, the more vibrant the face, the healthier the individual.

According to Arkive, "monkeys who have contracted the disease are noticeably paler and are not chosen as sexual partners as they do not have the desired natural immunity to malaria."

7. Capuchins were the first non-ape primates observed using tools

Capuchin monkeys are widely considered to be one of the most intelligent monkey species.
Capuchin monkeys are widely considered to be one of the most intelligent monkey species. (Photo: orangecrush/Shutterstock)

Capuchins are widely considered to be the most intelligent and self-aware of all New World monkeys, and they were one of the first primates other than apes to be observed engaging in highly skilled tool use in the wild.

The most common example of their tool use is the way capuchin monkeys crack open nuts — by placing them on pitted stone "anvils" and then hitting them hard with another rock. Another remarkable example of their intelligence and tool use is the way they rub crushed up millipedes on their bodies during mosquito season. The millipede mush serves as a natural insect repellent.

8. Grooming is used to strengthen and repair relationships

A trio of macaque monkeys enjoy a grooming session.
A trio of macaque monkeys enjoy a grooming session. (Photo: tratong/Shutterstock)

For monkeys, picking bugs, dirt and other debris off their companions is far from an indictment of their personal hygiene — it's an expression of affection and love.

Of course, monkeys aren't the only ones to engage in this behavior. In addition to other primates (from gorillas to lemurs to, yes, even humans!), social grooming is an important part of life for cats, parrots, horses, bats and many other animals.

9. A howler monkey call can travel three miles through dense forest

A mantled howler monkey perches on a tree limb.
A mantled howler monkey perches on a tree limb. (Photo: MyImages - Micha/Shutterstock)

At a whopping 128 decibels, the booming guttural howls of these large New World monkeys are liable to give you a headache, but these sounds are an integral part of their highly social communication.

According to National Geographic, "When a number of howlers let loose their lungs in concert, often at dawn or dusk, the din can be heard up to three miles (five kilometers) away. Male monkeys have large throats and specialized, shell-like vocal chambers that help to turn up the volume on their distinctive call. The noise sends a clear message to other monkeys: This territory is already occupied by a troop."

10. Only New World monkeys have prehensile tails

A Geoffroy's spider monkey clings to a tree using its prehensile tail.
A Geoffroy's spider monkey clings to a tree using its prehensile tail. (Photo: Erni/Shutterstock)

When people think of monkeys, there's often a very Disney-fied mental picture that comes to mind. If you've ever read or seen "The Jungle Book," you might be familiar with the troop of mischievous monkeys that use their tails to artfully navigate and play tricks on Mowgli and the gang within the dense forests of India. But the truth is, any wild monkeys that live in Southeast Asia are Old World monkeys, and the only monkeys that boast prehensile tails are found in the New World, which is on the opposite end of the Earth.

11. Monkeys love a relaxing hot soak as much as anyone

A macaque relaxes in a snowy Japanese hot spring.
A macaque relaxes in a snowy Japanese hot spring. (Photo: Sean Pavone/Shutterstock)

Well, Japanese macaques do, at least. These "snow monkeys," as they are affectionately called, have evolved to thrive in climates ranging from subtropical to sub-Arctic, and one of their prime winter hangouts is the Jigokudani Monkey Park in Yamanouchi, Japan. Ever since they began regularly frequenting these traditional onsens in the 1950s, they've become an international sensation.

"Snow monkeys mainly bathe to warm up in winter, but they sometimes do it in other seasons, too," MNN's Russell McLendon explains. "The warm water doesn't play a role in survival — their thick fur is enough to endure the region's harsh winters — so bathing is apparently a luxury activity motivated by comfort, social connections and cultural tradition."