Humans breasts are unique to humans – BI

Breasts come in different shapes and sizes. But there’s one thing they all have in common. They are unique to humans. More than 5,000 mammalian species inhabit this planet. Yet, Homo sapiens are the only life forms with permanent breasts. Some may call this human anomaly sexy. But it also begs the question: Why are human breasts so big and were they an evolutionary mistake?

Every other mammal develops temporary breasts during ovulation and/or nursing. Basically, their purpose is to produce milk. So once the milk is gone, the breasts disappear. But this isn’t the case for female humans whose breasts form during puberty, not pregnancy. So at some point in our evolution, something changed … why? For example, in 1987 biologist Tim Caro explored seven existing theories on this subject. One was that breasts allowed newborns to nurse from the hip, giving their mothers more mobility to multitask. But it doesn’t explain why breasts stick around after the nursing stage is over.

Humans breasts are unique to humans – BI

Early Puberty in Girls Is Becoming Epidemic and Getting Worse

Padded bras for kindergarteners with growing breasts to make them more comfortable? Sixteen percent of U.S. girls experiencing breast development by the age of 7? Thirty percent by the age of 8? Clearly something is affecting the hormones of U.S. girls—a phenomenon also seen in other developed countries. Girls in poorer countries seem to be spared—until they move to developed countries.

No scientists dispute that precocious or early-onset puberty is on the rise but they do not agree on the reasons. Is it bad diets and lack of exercise that cause growing obesity? Is it soft drinks themselves, even when not linked to obesity? Is it the common chemicals known as endocrine disrupters that exert estrogen-like effects (and also cause obesity)? Is it the many legal, unlabeled hormones used in the U.S. to fatten livestock? Some researchers even believe precocious puberty could be triggered by sociological factors like having no father in the home or even stress.

Alternet