Why Don’t Animals Need Haircuts? (Explained By Zoologist)

Fact Checked and Reviewed by: Mark Rhodes, Ph.D. - Wildlife Biologist
Dr. Mark Rhodes holds an MS in Fisheries and Wildlife along with a Ph.D. in Wildlife Ecology. He helps maintain our editorial standards of accuracy and quality. You can read more about Dr. Rhodes here.

One of the fastest ways for a human to change their appearance is with a haircut.  Haircuts even have different meanings for humans. From the high and tight military cut to the perms of the 80s.

Do you know who seems to be left out of all these hairdos? Animals! Sure, our cats and dogs need to be regularly trimmed but the almost uniform length of a lion’s mane or the matching fur length amongst a pack of wolves is one of the many factors that make individual animals of the same species look quite similar to each other.

But what’s going on here? Why don’t animals need haircuts like humans do?

Genetics primarily explain why most animals don’t need haircuts; their hair grows to a predetermined length and then stops or sheds. Seasonal coat changes in many animals, like dogs, act as natural haircuts. While grooming doesn’t trim length, animals such as cats groom to maintain coat health, removing dead hair. However, the genetic component is the biggest reason why animals don’t need haircuts. 

That’s the quick answer but we’re going to take a much closer look at what’s going on here and if there are any exceptions.

Understanding the Difference Between Fur and Hair

Let’s start by clearing up the difference between hair and fur as this can make things pretty confusing.

Mammalogist Nancy Simmons of the American Museum of Natural History puts it very simply when she explains that there isn’t any difference and “Hair and fur are the same thing.” There are differences in the consistency and hair is typically described as finer while fur is thicker. But both hair and fur are made of keratin and the real difference is simply how it presents.

Most often, hair is associated with humans and fur with animals but from a scientific perspective, they’re the same thing.

1. Genetics Limit Hair Growth For Most Animals

The best explanation for why animals don’t need haircuts comes down to genetics and most animals have hair that will grow to a genetically determined length. Once it reaches that point, it will either stop growing, fall out, or both.

A great example of hair growing genetics in action is the lion’s mane. A male lion has a short, thick double coat that’s relatively short, except of course for their famous mane. Their mane is typically 16 cm long (that’s a little over 6 inches) and that’s true for most lions. Their genes are controlling the length of the mane and the rest of their hair.

This applies to humans too and the hair on your head will grow much longer than the hair on the rest of your body. Researchers Neufeld and Conroy think they know why and they believe they’ve identified the genes that keep human hair growing so long but stop our primate relatives from getting a full beard. They’ve found a segment of DNA that generates a keratin protein and have identified it in gorillas, chimpanzees, and humans.

However, in humans, it’s what’s called a pseudogene which means it’s inactive. Neufeld and Conroy suggest that the inactivation of this gene in humans is “responsible for the inordinate growth of hair and beards.”

We can explain how this happened (via evolution) but understanding why it happened and what evolutionary pressures led to the change in human hair isn’t as clear. Some have suggested that long, thick hair all over our body would make it harder to swim, make it difficult to see subtle facial expressions like blushing, cause us to overheat, and more.

While we don’t know the exact explanation, we do know that differences in genes are at the root of it all.

2. Many Animals Shed and Replacement Hair Regularly

Many animals go through seasonal coat changes that function almost like a natural haircut.

You’re probably most familiar with this when it comes to our canine companions. While there are many breeds of dogs that actually do need regular haircuts (like the Shih Tzu or Yorkie) many others show the same growth and shedding patterns that we see in wild animals.

Breeds like huskies or Akitas have thick coats that protect them from the cold in the winter but as seasons transition to warmer months, these breeds undergo a significant natural “haircut” in the form of a major shedding phase. They rid themselves of this dense winter undercoat, allowing for a lighter, more breathable summer coat to dominate.

Even though most of these dogs are living happily in climate controlled homes, their coat still follows this natural cycle. Many owners will take these pups to the groomer to help nature along and prevent tufts of hair from covering their couch but these dogs still have a “built in” haircut process that takes them from winter coat to summer cut.

You can see a great example of a husky going through his seasonal coat shed (sometimes called “blowing coat” and you’ll see why). Even though he’s at the groomer, you’ll notice how much hair comes up just by plucking or using a fan:

Rabbits take it a step further in a natural process that’s beyond shedding- it’s called molting and it’s a process where rabbit will replace their entire coat. It’s like an old sweater being methodically unraveled and then reknit with fresh yarn. Similar to dogs and other animals, rabbits do this in order to replenish old fur and match their coat with the changing season.

3. Grooming Habits Can Help Manage Hair

Animals might not pick up a pair of scissors and start trimming but they do groom themselves and remove plenty of hair in the process.

Cats are famous for their grooming and when they’re not sleeping or eating, they’re probably grooming. In fact, cats spend around 30 to 50 percent of their day just grooming themselves! They have rough tongues (that feel like sandpaper) and are perfect for the job of removing dead hair or debris.

There’s still a genetic component that helps keep their coat a certain length, but regular grooming helps keep that coat healthy without the need for a haircut.

Some housecats will even groom each other and shared grooming (called allogrooming) is a regular part of a lion’s life. You can see a couple of lionesses sharing a grooming session with no scissors required:

Housecats and big cats are far from the only species to do this and it’s been seen in everything from bats and birds to chimps and cattle. Again, the genetic aspects that limit hair length are still the bigger factor but grooming helps remove dead hair and leave space for new growth similar to a summer trim for humans.

Do Any Animals Have Endlessly Growing Hair?

Some humans seem to have hair that grows endlessly and the Smithsonian even has the 17-foot beard of a Norwegian man. But even human hair won’t grow endlessly, at least most of the time, and will eventually enter a “resting stage” in which hair growth stops.

But are there any animals that have the ability to grow long hair similar to humans or even hair that will never stop growing?

There aren’t any wild animals that will grow endlessly long hair and while matting can a be problem for many species hair length for wild animals is limited by genetics or grooming. However, domesticated species like sheep and angora rabbits can grow seemingly endless hair that will become a major health issue if a human doesn’t intervene. 

It’s important to point out that unsheared sheep covered in their own coat isn’t a natural phenomenon and this occurs as a result of generations of selective breeding.

Why Do Only Humans Need Haircuts?

In most cases, it comes down to genetics and the hair on human heads doesn’t grow to a uniform length like the coat of a cat or dog. However, humans aren’t the only animals that need haircuts, and many domestic species like some dog or cat breeds, many sheep and some rabbits need regular haircuts too.

Frequently Asked Questions

We’ve covered the big picture reasons why wild animals don’t need to visit the barber shop, but let’s take a look at some of the individual species that folks might be asking about.

Why Do Dogs Not Need Haircuts?

Most dogs don’t need haircuts due to their genetic makeup which determines hair length and growth rate. It wouldn’t be practical for dogs to have long tangled coats that go down to their paws or cover their eyes. However, many dog breeds do need haircuts and these are the result of selective breeding where humans force certain characteristics to be more prominent from one generation to another.

That’s why a Shih Tzu needs to have their hair trimmed but the wild wolf doesn’t.

Why Do Cats Not Need Haircuts?

Similar to dogs, a cat’s genetic makeup limits how long their hair will grow. Some domesticated breeds, like the Persian, do need regular haircuts but this is a result of selective breeding and not something that occurs in nature.

Why Don’t Monkeys Need Haircuts?

Monkeys have evolved with genes that dictate their hair length, density, and growth patterns suited for their habitats and survival needs. While their hair does grow, it reaches a genetically predetermined length and then typically slows or stops. This natural regulation eliminates the need for haircuts, as seen in human-modified animals like certain breeds of dogs, cats and sheep.

Closing Thoughts

While humans frequently trim their hair for aesthetics, identity, or practicality, most animals have a genetic makeup that limits hair length and a built-in mechanism for hair management. After all, there aren’t any salons in the savannah or barbershops in the bayou.

While humans aren’t the only animals that need haircuts, selective breeding explains the long list of domestic species that depend on us for grooming and trims.