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Contrary to popular belief, humans aren’t the only creatures with opposed thumbs. Rather, it is as if we are in an exclusive club with several other animals that possess this rare trait. Driving, eating, playing and more – you use your thumbs every day, but you might be wondering: what is the opposed thumb? How is it different from other numbers? And what makes it so special?
Having an opposing thumb means you can rotate and bend your thumb so that it “touches” or touches the tips of other fingers, from fingerprint to fingerprint. This may not sound like much, but it is – most animals have their toes or toes only bend in one direction. Imagine that you only do everything with your fingers, if you did not have a thumb. The rotating thumb allows us to grasp, hold and use objects.
What other animals have sparse opposed thumbs? Many primates do this. These include the great apes, Old World apes, and the primates of Madagascar. Some other mammals and at least one frog species also have opposing thumbs.
Why are opposed thumbs so rare? The reason is simple, most animals don’t need them to survive. For example, most mammals use their front legs for walking, climbing, or defending. In such cases, the opposed thumb can get in the way or be easily injured. These animals do just fine without them.
Even some animals with human hands do not have fire-fighting thumbs. Raccoons, for example, collect and wash their food with their hands. Sometimes they also manipulate other objects. Their arms have sensitive nerve endings that allow them to recognize objects by touch, but their arms do not have the same maneuverability as primates. And some monkeys don’t have thumbs at all!
Check out our following list of 10 favorite animals with opposed thumbs.
1. People
As humans, we rely heavily on our opposing fingers for many of our daily activities. Try this – take a few minutes and try simple tasks without using your thumb. Fold it across your arm so it doesn’t get in the way. Is it difficult to brush your teeth? Hold your fork? Open the door? Use a video game controller?
Not only do humans have opposing thumbs, but we can use our thumbs and hands in ways that animals cannot. Slide your thumb across your palm to touch the base of your ring and pinky fingers. Then, use the tip of each of these fingers to touch the base of your thumb. Animals with opposed thumbs cannot do this. Humans have an increased dexterity, which allows us to easily manipulate tools.
We may not be the only mammals with opposed thumbs, but we have many other characteristics that make us unique in the natural world. For example, we have an unusually large brain for our size, and we can think in abstract terms such as time and spirituality. We have a lowered voice box and a bone under the tongue that is not attached to other bones – together they allow us to speak words. We, of course, walk on two legs. And we make up for the lack of hair with clothes. People are pretty strange animals!
Learn more about humanity’s place in the natural world.
2. Monkeys
Large apes, including gorillas, chimpanzees, bonobos, and orangutans, as well as smaller monkeys called gibbons, have opposing thumbs. In fact, they’ve taken a step forward with opposing toes – the big toe can also be opposed!
Human and monkey DNA are 97% similar. We each have genetic information that codes for a hand with four fingers and an opposing thumb. But how do monkeys use their opposing fingers?
They use their thumbs to climb trees, grab branches, and hold tools – for example, using a small stick to pick up ants or termites from the nest. Some monkeys can build leaf shelters to protect themselves from rain. They groom each other by pinching annoying insects with their thumb and forefinger. They also use their thumbs when gathering food, such as picking fruit or peeling a banana – a task that would be nearly impossible without the opposing thumb.
3. Monkeys of the Old World
Old World monkeys are species found in Asia and Africa, as opposed to New World monkeys in the Americas. There are twenty-three species of Old World monkeys, and most of them, including grivnas, baboons, and macaques, use their opposite fingers to grasp tree branches and other objects.
However, not all monkeys in the Old World have fire fingers. In fact, the colobus monkey has no thumbs!
Learn more about monkeys.
4. Lemurs
Lemurs are primates that live only on the island of Madagascar and several other islands off the coast of Africa. The smallest of about 100 species of lemur is only 3 inches long, while the others are several feet high. Some researchers refer to lemur thumbs as “pseudo-opposite thumbs,” which means they are almost opposite, but not quite. Like other primates, they use their thumbs to grab onto branches and manipulate food. Other primates of the lemur family – the potto and the loris – also have pseudo-opposite thumbs.
Learn more about lemurs.
5. Chameleons
Chameleons use a special thumb-like arrangement of toes to grab onto branches and branches as they climb. Three toes form a “medial bundle” extending from the midfoot. Two fingers form a “lateral tuft” that goes to the side. On the hind feet, this arrangement is reversed, with two toes in the medial position and three to the sides.
Learn more about chameleons.
6. Koalas
The koala, Australia’s famous marsupial, is unlike any other animal in that it actually has two fire fingers. These thumbs are angled to three fingers. The koala uses these two parts of its hand – thumbs and fingers – to securely climb and climb tree branches.
Koalas also have opposed toes on each foot. This brings them a world record for the most six opposite numbers!
Learn more about koalas.
7. Giant pandas
Giant pandas have an opposed thumb, which is called a false thumb. The panda’s false thumb is not composed of the distal and proximal phalanx bones, but an enlarged carpal bone, one of the many bones that together form the wrist. However, the false thumb functions as an opposed thumb against the five fingers, allowing the panda to grasp bamboo shoots and bring them effectively to the mouth.
Learn more about giant pandas.
8. Possums and possums
Virginia opossums have a number of unique characteristics. They are the only marsupials in North America to carry babies in a pouch like a kangaroo. They have prehensile, grasping tails and opposed thumbs (actually the fifth toe) on their hind legs. Together, their tails and thumbs help them climb trees to hunt or avoid danger. Interestingly, the opposite thumb of the possum has neither a nail nor a claw.
Australia’s marsupial possums also have fire fingers. All but two possums have first and second toes on their front paws, which are opposed to the other three toes. Without claws, the first toe of the back of the foot can also be contrasted.
Learn more about possums.
9. Wax frogs made from monkey leaves
The tree or tree frogs of the Phyllomedusa family are one of two non-mammals to make our list. Like monkeys and other animals, frogs use their opposing fingers to grab onto tree branches as they move through the crown. From here they got their common names: waxy monkey leaves or tree frogs.
Learn more about tree frogs.
10. Monkeys of the New World
Some of the New World monkeys — those that live in America — have opposite fingers. These include saki, ukari, tamarin, woolly monkey, night monkey, owl monkey, capuchin, and squirrel monkey. Like lemurs and lorises, some of these monkeys are classified as having pseudo-opposite thumbs.
Animals with the opposite thumb list
Next: New Research: Another Ancient Sloth Revealed!
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