Human breasts are weird. They're one of the few organs that aren't fully developed at birth, our offspring depend almost entirely on them, and while in most mammals the breast becomes enlarged exclusively during lactation, we are the only species on the planet to have perpetually swollen mammary glands. But why? The latest episode of AsapSCIENCE is here to explain why breasts are one of the best things to human to Homo sapiens… evolutionarily speaking.

First up, the fact that the human body can convert blood into milk to deliver all those great proteins, sugars, and fats to our offspring via the breasts is one of the reasons our species has enjoyed such incredible success. Think about all the things that can go wrong with other types of babies - baby birds and reptiles depend on their parents to bring them food they've hunted, so the survival of these offspring depends wholly on the availabiity of food sources and the parents' ability to find it.

From the get-go, human babies just have to lie back and take it all in. So long as the mother has access to enough nutrients for herself, things will be fine. 

Breasts come in a ridiculous array of shapes and sizes, and although studies have found a positive correlation between body weight and breast size, genes also play a crucial role in determining what an indviudal's pair will look like, plus which one will end up being the smallest. Strangely enough, around 50 percent of the general population has one boob that's smaller than the other, and most commonly, it's the left one.

As the video explains, no one's entirely sure why breast assymetry occurs so frequently, but research suggests that it has to do with the hormones that flood into our bodies when we hit puberty. While both men and women are born with nipples and mammory glands, only women experience enlargement during puberty, and this is a uniquely human quality. 

If you want to feel slightly awkward about your areolas (of course you do!), you should know that the little bumps they're covered in are called Montgomery's glands. This Montgomery fellow sure got lucky. These glands have the important function of secreting oils to keep the nipple lubricated and possibly even delicious for our babies as they feed.

And the nipple doesn't just provide one hole to feed from, it's covered in tiny holes that are inperceptible to the human eye through which the milk can be consumed.

All of which is distinctly unsexy, and yet, many cultures around the world harbour a bit of an obsession with these curious organs. According to the video, 300,000 breast augmentation surgeries were performing in 2014 alone - and that's just in America.

It's not hard to see why humans are so drawn to them though - they're a source of great pleasure for both men and women. Yep, studies have shown that stimulation of nipples not only enhance sexual arousal in 82 percent of women, but also in 53 percent of men. We're going to go ahead and let AsapSCIENCE explain that one in the video above… You're welcome.