Why are human breasts big?

The breast has many different shapes and sizes but one thing in particular is that only humans have large-sized breasts.

There are more than 5,000 species of mammals that live on this planet. However, only humans are the only species with large-sized breasts that persist throughout life, according to IFLScience.

The question arises: Why is the human breast so big, is it an error of evolution?

Each other mammal only develops breasts temporarily during ovulation or lactation. Basically, the purpose of breasts in animals is to make milk and to breastfeed. So once the milk is gone, the animal's breast also disappears.

But in other humans, the breasts form during puberty, not when the pregnancy begins, according to IFLScience.

Only humans have big breasts.

In 1987 biologist Tim Caro discovered seven theories on this topic. In it, he said that the human breast allows babies to feed from the side, giving the mother more flexibility to do many other tasks.

But his theory still does not explain why after the breastfeeding period, the woman's breasts still exist.

Perhaps the most popular idea was first proposed and later discovered by zoologist Desmond Morris in a book called "The Naked Ape" , published in 1967.

In it, Morris assumes that the breast develops as a sexual symbol to replace the bulging buttocks of other female primates during ovulation, according to IFLScience.

According to this hypothesis, as soon as the primitive man starts walking in an upright position, men are no longer able to tell when a woman is puberty and the breast may have formed as an answer to this question.

This theory will at least explain why a woman's breasts develop during puberty, but it still cannot explain why human breasts persist after menopause.

Take a closer look at the human breasts. The biggest difference is that they contain more fat than other mammals. Fat fills breast tissue, posing it as if it had milk, but survived without losing after losing milk as in other animals, according to IFLScience.

The human chest may be too large, which can cause back pain and tightness in the chest. This is why many women make small breasts. In the US alone, there are more than 61,000 small-breasted people in 2016.

But breasts are not only uncomfortable for some people, it can also cause death for women. Breast cancer is the number one cause of death for women worldwide. It affects about 1.5 million women each year and kills 570,000 people in 2015, according to IFLScience.

However, according to scientists, breast cancer is not common among other primates. This may be due to the increased risk of cancer by age and other primates that do not live long enough to grow. Or perhaps it may involve permanent breast tissue only in humans.

Cancer occurs more commonly in tissues that are capable of rapid division. Breast tissue divides at a rapid rate so there is a greater risk of cancer. That may explain why removing both breasts reduces the risk of breast cancer in women by 95%.