Before explaining this question, we must first figure out what is tin bone?

Before explaining this problem

We first need to figure out

What is tin bone?

This thing

As the name suggests, it is the bones in the tin

Most of them are stick-shaped

However, with different species, its shape also changes certainly

The tin bones of male walrus are like batons

The top of the tin bones of squirrels are spade-shaped, and there are also sharp teeth

In addition,

It is not connected to other bones

When summoned, it will be pushed to the tin tin

The role of

in the qualitative part of the

provides many conveniences and benefits for animals to "applaud"

Benefits 1: Trigger ovulation

For some species,

ovulation only when it reaches xxoo (like a female cat)

So some people think that tin bone can stimulate ovulation

Benefits 2: Overcome friction

Scientists also proposed the "friction hypothesis"

(vaginal Friction hypothesis)

believes that tin bones can make males overcome friction

makes it easier for themselves to enter females

Benefits 3: Help reproduce

Some people also believe that tin bones can prolong the time

Because for males,

prolong the time can reduce females

chance to mating with other males

This theory is called "cock-blocking" (cock-blocking)

This behavior also means that

can increase the chance of female pregnancy

gives males more initiative

Why do humans have no tin bones?

Actually, a long time ago

Our direct ancestor ape

is

But the reason why tin bones were evolved and eliminated

mainly have the following three reasons

1: monogamous marriage method

This method produces