Dumbest Mammals

Written by Abdulmumin Akinde
Published: September 20, 2022
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Mammals are top of the evolutionary ladder, meaning they’re expected to be among the most advanced groups of animals on the planet. Indeed, the success of most mammals shows just how superior they are over other animal species. However, there are exceptions to every rule. Not all mammals are intelligent. In fact, some mammals rank high on the list of dumbest animals in the world. This post lists some of the dumbest mammals in the world and the things that make them so dumb. 


Giraffes are known for their long necks

Giraffes are easily distinguished by their long necks

©Craig Fraser/Shutterstock.com

The giraffe is arguably one of the most recognizable animals on the planet. They’re known for their height and extremely long necks. However, this is probably the first dumb thing about this majestic mammal. The giraffe’s long neck is only suitable for reaching leaves high up on trees. They’re incapable of reaching plants on the ground with their neck. Although this silly design flaw isn’t really the giraffe’s fault, it’s undoubtedly not a smart adaptation since there’s a limited number of trees in their natural habitat. 

The giraffe is not entirely dumb, though. For a long time, people considered them stupid creatures because they were deemed incapable of communication. We now know that this isn’t true. Giraffes can communicate using low moans and grunts that are inaudible to humans. They also communicate through touch and with their eyes. This shows they might not be the dumbest mammals on the planet after all. 

Slow Loris 

Most Vicious Animals

Slow lorises are viciously territorial, and they use venom as their weapon of choice.


There’s a reason dumb people are called “slow-pokes.” Therefore, it isn’t surprising that a literal extremely slow animal makes it on this list of dumbest mammals. As its name suggests, the slow loris is a slow-moving primate. It has big round eyes and a chubby face that makes it look quite adorable. But that’s about the most impressive thing about this mammal. 

Slow loris spends most of its day lazing around like a sleeping baby. The reason for this is that they’re primarily nocturnal. They eat and move slowly and are often too slow to escape a predator attack. When startled, slow loris will raise their hands in the air. While this might seem like a silly thing to do, it isn’t exactly a terrible idea. Raising its hands this way helps to release a poisonous venom that can kill an attacking predator. So while raising its hand as a defense mechanism makes the slow loris look silly, the move isn’t an entirely dumb one. 

Norwegian Lemmings 

Dumbest Animals in the World: Norwegian Lemmings

Norwegian lemmings spend the winter in underground tunnel systems, located under the snow, where they find shelter from predators.


The Norwegian lemming is a species of lemmings native to Norway’s tundra and fells region. They’re active both day and night, spending the cold winter months underground. 

Lemmings look like a slightly larger version of your cute pet hamster. But they’re anything but cute. In fact, part of what makes this rodent one of the dumbest in the world is their aggressive nature and inability to stand down from a fight. Norwegian lemmings don’t mind picking fights with animals significantly larger than them when threatened. With a weight of just 0.25 lb (112 g) and 6 inches in length, they’re easy prey for cats, birds of prey, and other predators. But instead of scurrying away or burrowing like many other critters would, a lemming would stand its ground to fight. Unfortunately, while being aggressive may deter some predators, the inadequacy of their defensive weapon means they don’t stand a very good chance against many big animals they tend to challenge mindlessly. 


Koalas are known as some of the dumbest mammals in the world because of their limited diet

Koalas are very picky eaters and have a diet limited to only 30 species of eucalyptus trees

©Andras Deak/Shutterstock.com

One of the most recognizable creatures of Australia, Koalas are marsupials. This means they’re more closely related to the kangaroo than the bear (after which they’re wrongly named). Koalas love to roll around and seem to stare all the time. While humans enjoy watching them do this, it indicates just how dumb this animal is. The koala has the smallest brain-to-body-mass ratio of all mammals, which makes them one of the dumbest mammals in the world. 

One of the dumbest things about the koala’s habits is its highly restrictive diet. Even though they can eat pretty much any plant they want, koalas prefer to eat leaves from the eucalyptus plant. Even worse, even though there are about 600 species of eucalyptus, the koala likes to eat only 30 of these. The koala is one of the few animals in the world whose stomachs are adapted to feeding on the eucalyptus. Still, their favorite food source is so low in nutrients that the animal has to be in a low-activity state all day to conserve energy. 

Some koalas have been known to starve to death simply because they could not identify their food. Koalas are also quite dirty and may spread various diseases, including chlamydia. 


sloths are known as some of the dumbest mammals in the world

Sloths have an incredibly slow metabolism


As far as being slow and dumb is concerned, south and central America’s version of the koala is the sloth. However, for the sloth, being slow is because of their slow metabolism and not because they’re addicted to a single food source. This freakish mammal is known as one of the laziest animals on earth. They’re also among the dumbest mammals in the world. 

Sloths spend most of their day sleeping, and they move extremely slowly. They’re on a tree throughout the day and will only come down occasionally for a quick bathroom break per day. Getting back into the tree is often a challenge for them. In fact, some sloths have been known to slip and fall to their death while trying to climb back into a tree. Experts say it’s because they often mistake their own limbs for a tree branch. 


Although the idea of animal intelligence may be suggestive, the dumbest mammals included in this list are the ones that don’t show impressive survival adaptation in their preferred habitats. Their ineptitude in surviving predators, feeding, or responding quickly to external stimulus ranks them high among the dumbest mammals. 

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The photo featured at the top of this post is © Andras Deak/Shutterstock.com

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About the Author

Abdulmumin is a pharmacist and a top-rated content writer who can pretty much write on anything that can be researched on the internet. However, he particularly enjoys writing about animals, nature, and health. He loves animals, especially horses, and would love to have one someday.

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  2. The Cold Wire, Available here: https://www.thecoldwire.com/dumbest-animals-in-the-world/