How Big is a Horses Brain

How Big is a Horses Brain

There are many jokes out there about how “size matters.” When people talk about the size of a horse's brain, it's often compared to the size of a large walnut. Although this may be accurate for certain breeds, it's not what the average brain size of a horse happens to be. It would be more accurate to say that the average brain of a horse is about the same average size of a human child. It weights between 1.5-2 pounds for most horses.

What is unique about the horse's brain is that unlike other animals, it is remarkably structured in the same way as a human brain. The only two primary differences are how the fine-motor skills are used and the areas of language development. Most of a horse's brain is used to analyze the information it receives from its surrounding environment.

What Is the Actual Size of the Horse Brain?

Different breeds are going to have different brain sizes because of the shape of their skull and the size of the horse. For adults, most horse brains are going to range from about 1 inch in diameters to more than 4 inches in diameter. This makes the average brain size for horses about 2.5 inches in size when all adults and breeds are considered.

It's also important to note whether or not the discussion involves the brain itself or the cavity within the skull where the brain sits. The cavity for most horses could fit something the size of a grapefruit because of the extra space it contains. The pituitary gland, pineal gland, olfactory and auditory bulbs, and extra cerebral fluid to cushion the brain against the horse's fast movements are all found within the skull cavity.

Do Horses Have the Intelligence of a 12 Year Old?

Because of the size, shape, and composition of the brain of a horse, many scientists have theorized that their intelligence levels are similar to that of a human child. When you hear about horses like Beautiful Jim Key, it's difficult to believe that the theory is incorrect.

Born around the turn of the 20th century, Beautiful Jim Key was an American horse that could perform basic language comprehension tasks. The horse could perform basic math, could read and write, and was even proficient in spelling. Another horse, Clever Hans, was unique because he could read unconscious human behavior and predict what people would do.

So how big is a horse's brain? It's larger than some animals, like dogs and cats, but smaller than other animals – but it may also be one of the most intelligent creatures with whom we share our planet.

How Are the Brains of Humans and Horses Different?

Besides the size of the brain and the basic differences noted, there are some interesting differences that you'll find when comparing the brain of a human with the brain of a horse. Horses have a cerebellum that is much larger than humans, which is where coordination and sensory perception take place. Horses must typically be able to run just one hour after being born and this brain structure allows this to happen for the animal.

This means that when a horse is either taught a specific movement or learns it on its own, the larger cerebellum means that the horse will never forget that movement.

Horses also rely more on their sense of smell than their other senses. The brain of a horse can process thousands more factors in scents detected than humans, which creates a world view that we humans can only imagine.


In the end, humans have the ability to see, interact, and use oral communication in coordination with their hands and feet in order to change the world. Horses are experts at understanding what the environment around them is doing, perceiving what body language means, and being able to comprehend basic language understanding and be able to communicate that.

By understanding these differences, humans and horses can help one another be able to reach their full potential. It's a unique relationship that cannot be fully understood unless someone has spent some time around a horse.

The Horse Brain Can Be Divided Into Three Sections

The first section of a horse's brain, and possibly the most important, is the cerebellum. It's sometimes referred to as the Hind Brain. Without this part of the brain, a horse would be tripping over its feet and it is the largest section because for the horse, movement is life. Yet the cerebellum cannot function on its own to give a horse the quality of life it deserves. It needs a little help.

The second section of a horse's brain is called the Mid Brain. This is where the communication centers are placed. You'll find nerve bundles in this section of the brain that convey signals between each section and throughout the body of the horse. Think of this section of the brain as a server which is connecting two different computers into one fully functional resource that can be used. 

The third and final section of the brain is called the Forebrain. This part of the brain would be similar to the gray matter that we see in our own brains. This is where the remainder of the commands that the horse needs to process are held outside of the coordination, function, and general awareness that the horse has.

So why is it so common to hear that the horse's brain is similar in size to a large walnut when this is clearly not true? It's because this reference is actually about the cerebellum hemisphere of the horse brain. It's the part of the brain that controls balance, body function, muscle coordination, and similar activities for the horse. Because it's the largest section of the brain, it mistakenly becomes the reference for the entire brain itself.

Has the Size of a Horse's Brain Changed Over Time?

In the past, horses were believed to have brains that were up to 16% larger than they are today. When domesticated horses over several generations are compared to wild horses of several generations, the wild horses may have brains that are 30% larger.

Some believe that domestication has caused the brains of horses to shrink over time because there are fewer demands on them to explore their environment. Others believe that the brains have grown smaller because of human interference with their natural evolution as breeds. Whatever the case may be, we can see that there are many surprises that are contained within the mind of a horse. Horses are living proof that size doesn't always matter when it comes to intelligence.

So how big is a horse's brain? The answer is that it is big enough.

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