We've all heard the saying and as much as we want to disregard it as nonsense, there's

actually a scientific answer to the question.

Get ready because we've got the truth.

Evolution has driven the development of the size and shape of the penis, and between species

the proportion of penis to body size can vary greatly.

But why?

Why are there different ratios of penis to body size in animals?

It all has to do with natural and sexual selection.

First, we know what you're thinking.

What is the animal with the largest penis to body ratio?

Sorry human's, but we didn't win this competition.

The answer is... the barnacle.

You heard right.

The creature that lives on the sides of boats and the rocks of beaches has the largest penis

to body size proportion out of any species.

Their penises can reach up to ten times the length of their body.

The reason that barnacles have such a long penis is because they cannot move, and a mate

might be a long ways away.

When this happens the barnacle elongates its penis to ten times its body size to copulate

with a female counterpart.

Going from small to gigantic, you may be surprised to learn that the largest animal on the planet

also has one of the largest penis to body size proportions of the animal kingdom.

Blue whales are on average 100 feet long and the blue whale penis is between 8 to 12 feet

in length.

This gives it a penis to body ratio of about 10 to 1.

That gives whale watching a whole new meaning.

Snakes bring penis proportions to a whole other level though.

But it's not the length or size, it's the number that is surprising.

Snakes have two penises called hemipenes.

That's right, not one, but two penises.

This is because of the way snakes mate.

Snakes form what is called a mating ball, where around 100 males compete for a single

female.

And you thought dating apps were rough.

With that kind of competition, it's advantageous to have a penis on either side of the body

just in case the snake finds itself next to the female.

He wouldn't want to miss his chance to mate just because he was facing the wrong way.

What if someone had a penis that was the same size as their body?

That'd be wild right?

Well let us introduce you to the banana slug.

It has a penis to body ratio of 1 to 1.

Yes, the banana slug's penis is the size of its entire body.

That is impressive, except for the fact that the banana slug's mate sometimes eats the

penis after copulation.

So, at that point the banana slugs raito goes from 1 to 1 to 0 to 1.

Ouch.

Speaking of 0 to 1 ratios, you may be surprised to learn that the rooster, also known as a

cock, has a penis to body ratio of 0 to 1.

Roosters like 97% of birds don't have a penis outside their body at all.

Instead they have what is called a cloaca, which is a tiny nub that the rooster uses

to deposit sperm into a chicken.

The nicknames of animals don't always make sense.

Or is it the other nickname that doesn't?

Other organisms not only have crazy penis to body proportions, but crazy penis shapes.

Take a pig for instance.

They can have a penis to body ratio of 1 to 2, meaning their penis can be half the length

of their body.

But that's not the craziest part.

The pig penis is an “S” shape, ending with a corkscrew.

The shape allows male pigs to interlock with the female during mating to make sure the

job gets done.

And if you think that's wild, the tapir, which has about the same proportion of penis

to body as a pig, has been known to use its penis to scratch its own back.

Who knew the penis was such a versatile appendage?

But why is there such a variety of penis proportions and shapes?

All penises have the same function, except for maybe the tapir's.

Really though the penis has one main function and that is to deliver the male's sperm

into the female's reproductive system, so that the egg can be fertilized in the fallopian

tube and reproduction can happen.

That's the true purpose of life in the animal kingdom, to create offspring and pass on your

genes.

So why the diversity of proportions for such a simple task?

Well like everything else in biology evolution plays an important role.

If you think back to your high school science class, evolution is the changing of species

over time.

More specifically, the process of natural selection choosing which organisms have the

best traits to survive and reproduce in their environment.

The penis obviously plays a role in the reproduction of species, and therefore, evolution must

have driven its development.

And scientists have many different theories as to why penis proportions vary so much between

species.

One surprising trait of penises is that they are much more complicated than they should

be.

If the main function of the penis is to serve as a sperm delivery system, then why is it

so complicated?

Well the shape and proportion of the penis most likely evolved to ensure that successful

mating occurred as often as possible.

Other than dolphins, humans, and our primate relatives, not many animals have sex just

for fun or pleassure.

So the shape and proportions of the penis did not evolve to create more pleasure for

the females of the species, except maybe in humans, but more on this later.

One theory as to why there are different penis proportions is because of environmental factors

in a species habitat.

Species that live in high altitudes or colder climates tend to have larger penises.

This is most likely due to different mating strategies in these regions.

For example, animals like elephants and wildebeests that live in low altitudes with warm climates

tend to live in large herds.

In these environments and groupings there is much more competition between males to

mate with females.

Males often fight one another for access and the right to mate.

Natural selection would select for large body size, which would help the males dominate

their competitors.

Once the fight has been won, it doesn't really matter the size of the penis, because

that male has exclusive rights to mate with the females of the herd.

Therefore, in warmer regions it would seem that large bodies and small penises are more

beneficial traits to have than the other way around.

That is why species that live in warm lowland environments tend to have smaller penis to

body size ratios.

On the other hand, species that live in cold or high altitudes tend to be more solitary

or isolated.

This means less fighting for mates, but more competition to make sure your sperm reaches

the female's egg first.

Take the walrus.

They are known to have both one of the largest penises and penis to body size proportions

out of any animal in the world.

They live in the frozen arctic, which supports relatively few individuals.

Without large populations, walruses tend not to come in contact with one another very often.

That is why when sexual encounters occur it is important that the male walrus is successful

in passing on his genes.

Research in walruses and other animals suggests that the larger the penis the more likely

the male is to inseminate a female.

Therefore, in cold environments it is more beneficial to have a large penis and smaller

body.

Successfully mating is much more important than successfully winning a fight in these

regions.

Larger penises may deposit sperm closer to the fallopian tubes thus giving those sperm

a better chance of reaching the female's egg.

Penises of the right size and shape may also scoop out rival sperm from a different male

during intercourse.

Wild, we know, but in the game of reproduction, there can only be one winner.

Evidence also suggests that penis proportions were driven by a second process of evolution

as well.

The name of this process is sexual selection.

Sexual selection is when a specific trait is selected for by the sexual desires of a

male or female in a species.

Most often it is the female of a species that does the selecting.

This trait is chosen not because it helps the animal survive better, but because it

is desirable to the opposite sex.

Think of a peacock.

The male peacock has extremely large vibrant feathers.

This is not a good trait to have when trying to hide or get away from predators.

But, the female peahens will typically only mate with peacocks with the brightest, most

luxurious feathers.

Therefore, peacocks risk their lives for beautiful feathers, because without them the peahens

wouldn't mate with them.

No mating means no genes being passed on to the next generation like dull feathers or

penis size.

So what about penis shape and proportion?

Could the variety of penis proportions between species have been caused by sexual selection?

Absolutely.

Different species have different traits they find desirable.

The penis is just another trait for a female when selecting a mate.

Bigger might be better, or it might not be, it's up to the females.

Really what it comes down to is that the traits females find most attractive are what get

passed down.

So for all intents and purposes females oftentimes drive the evolution of males and this includes

penis size and proportion as well.

It is important to remember that animals don't wear clothes.

That seems like a silly sentence, but stay with us.

Until recently in the evolutionary scheme of things, even humans didn't wear clothes.

So, the penis was always hanging out for the females of a species to see and assess.

There is no hiding or denying it.

No matter what you may have heard, female preference for penis shape and proportion

in the past most likely drove the variations we see today.

Now let's talk about something a little closer to home, humans.

If you are watching this video you are most likely a human.

Humans are interesting because we have big brains and intelligence and culture.

But we can't forget that we are animals too.

Our big brains and other traits were selected for through natural and sexual selection,

just like all other living things on this planet.

When talking about male genitalia, it is interesting to note that all human males have a larger

penis to body size proportion than any of our closest primate relatives.

Yay us!

Why is that though?

When we compare proportions of other primates, what we find is surprising.

The largest primate, the silverback gorilla, may be able to rip your arms off without breaking

a sweat but also has the smallest penis at just 1 inch.

This is likely due to the environment and social structure of gorillas.

Since gorillas live in harems it is much more advantageous for a gorilla to have a large

body to fight off other males.

Once a male proves dominance he can mate with all the females in the harem.

Therefore, there is no reason to have a large penis as a gorilla, and in fact it would only

get in the way.

Our closest living relative in the animal kingdom is the chimpanzee.

Chimps have an average penis size of around 3 inches.

This is over twice as large as the gorilla and chimps are much smaller.

So why the difference in proportion?

And what can that tell us about humans?

Well chimpanzees are notoriously promiscuous when it comes to sex with female chimps usually

having more than three mates at a time.

This means that male chimps must do everything they can to make sure their sperm fertilizes

the egg first.

A larger penis correlates to higher reproductive success in chimps, either because of its ability

to scoop out rival sperm or to give its sperm a head start.

So then what about us humans?

Why do we have a larger proportion of penis to body size than other primates?

It would seem that human males have been placed under heavy sexual selection by human females.

Several studies have found that women prefer a bigger penis in males.

Remember, in early human history there were no clothing, so females could always see what

the males were working with.

It is during this early time in human history that females started selecting for larger

penises, thus giving human males of today a larger penis to body size proportion than

other primates.

It is interesting to note that recent studies have corroborated this theory, in that on

average, human females find larger penises to be more attractive in a male.

However, height and body proportions also play a big role when females rate males on

attractiveness.

This suggests that not just penis size, but the proportion of penis size to body size

was selected for by females of the past.

If this is the case in humans then there is no reason to assume it isn't true in other

species as well.

We are animals after all.

Basically what it comes down to is that penis to body proportions vary between species because

of natural and sexual selection.

The environment, mating practices, social structure, and sexual characteristic preferences

all played a role in creating the diversity of pensies we see today.

We are all part of this planet called Earth and we are all a product of evolution.

Just remember, a proportion that may be attractive for one individual or species, might not be

to another.

For another video about how insane animals are check out Strongest Animals for Their

Size and Their Abilities.

Or go watch What If Animals Went To World War With Humans?