fully developed at birth, and of course are a major obsession in western culture.

發育完全的器官，當然也是西方文化中引人入勝的話題

Yet there is so much about breasts that isn’t discussed or is deemed taboob, sorry “taboo”.

但有很多關於胸部的話題還沒被詳盡的討論過或是被視為"禁胸"，噢不，是"禁忌"

So, what does science say about breasts?

那在科學方面是怎麼看待胸部的呢？

Forget water into wine - what about blood into milk? Proteins, sugars, and fat are pulled

先把水如何變成酒的故事(聖經故事)擺一邊吧，來談談血如何變成牛奶的吧！蛋白質、糖分和脂肪

from a mother's blood supply to make milk, and it is this action that has made mammals

從母親的身體裡分泌出來形成母乳，這是一項哺乳動物發展地很成功

so successful. Unlike birds or reptiles, whose young are dependent on parents to bring them

的機制，不像鳥類或爬蟲類一樣必須依賴父母親帶著外面

outside food such as insects, mammals, from the word mammary, access their nutrition at

的食物，例如昆蟲、哺乳動物(字源為 mammary)，哺乳類動物

a young age from the secretion of a mother's milk.

從小就可以透過母親分泌出的母乳取得營養

Breasts come in all shapes and sizes and though there is a positive correlation between breast

胸部有著各種形狀與大小，然而胸部大小與其重量有著相當的

size and weight, genes also play a crucial role in the size of boobs. 50% of the time

關聯性，另外，基因遺傳是影響胸部大小很重要的原因。有一半的機率

one breast is larger than the other, most commonly the left boob, known as breast asymmetry.

一邊的胸部會比另一邊大，通常是左邊的胸部比較大，我們將它稱之為胸部不對稱

This asymmetry is normal and though scientists aren’t entirely clear why, a possible contributor

這種不對稱的現象很正常，雖然科學家也並不完全了解原因，但有可能的原因是

is the hormonal changes that happen during puberty. On top of this, the size of your

因為賀爾蒙在青春期時的改變所造成的。也因為這樣，你胸部的大小

breasts vary from week to week! Yup, the production of estrogen and progesterone

每一周是不一樣的，因此動情激素跟黃體素

throughout the menstrual cycle changes the size of your breasts.

在經期的時候出現改變了胸部的大小

Both men and women have nipples and mammary glands, but usually only women have them

男姓和女性都有乳頭及乳腺，但只有女性會在青春期

develop at puberty. This characteristic is uniquely human as other mammals breasts only enlarge

的時候繼續發育。人類及其他哺乳類動物特有的特徵就是養育嬰孩時胸部

during nursing. The ring of pigmented skin surrounding the nipple is called the areola

會脹大。乳頭周圍那一環暗色的皮膚叫做乳暈

which is covered in little bumps called Montgomery's Gland. While lactating, the glands make oily

藏在那一圈暗色肌膚底下的是蒙哥馬利腺(乳暈腺)，當餵奶的時候，乳腺會

secretions that keep the nipple lubricated and may also release compounds to make the

分泌出油滑的液體保持乳頭滋潤並釋出混合物

nipple seem yummy for a baby.

讓小孩認為乳頭很可口

The nipple isn’t composed of a single orifice but has many tiny holes you cannot see with

乳頭並不是只有一個孔，而是由許多你無法用肉眼看的小細孔

the naked eye. After having a baby, receptors in the nipple detect when the baby begins

所組成的。有了小孩之後，乳頭會接收到小孩開始在

to suckle, sending messages to the mother's brain, causing a release of oxytocin and continued

吮吸的訊息，並將在訊息傳受到母親的大腦，因此釋出催產素及大量的

production of prolactin. Oxytocin causes cells that line the mammary glands to contract and

泌乳激素。催產素造成乳腺的細胞收縮

is also known as the cuddle hormone, as it enhances the bonding experience between mother

這也是所謂的擁抱荷爾蒙，它能夠增加母親及小孩之間的

and child. The hormone prolactin is essential in making milk. This whole hormonal process

聯繫感。泌乳激素對母乳的產生非常重要，這賀爾蒙其實

can be triggered after only hearing a baby cry, even if it isn’t your baby!

在聽到小孩的哭聲時就會產生了，即使是別人小孩的哭聲。

Babies love breasts, but so do people. Research has found that people spend more time observing

我們都知道小孩愛胸部，但誰不愛胸部呢？研究指出人類花在盯大胸部的時間

large breasts with a certain hip to width ratio - potentially explaining why breast

比盯豐臀的時間還久，這也可以證明為何

augmentation surgeries are the most prevalent form of plastic surgery, with 300,000 surgeries

豐胸手術是所有整形手術中最流行的，在2014年，光是美國，

being performed in 2014...in America alone. However, the same research shows that people

就有三十萬個豐胸手術的例子。研究還指出，不同形狀與大小的胸部

prefer breasts of all different shapes and sizes, and medium sized breasts were actually

都有人喜歡，然而中型大小的胸部

rated as statistically most attractive. Breasts don’t only create joy for others, but also

在統計數據上來說是最吸引人的。胸部不只能愉悅別人，也能

for oneself. Studies show that stimulation of nipples enhanced sexual arousal in 82%

愉悅自己。報告指出刺激乳頭能對82%的女性及

of women and 52% of men. Interestingly an fMRI scan that mapped the brain's response

52%的男性帶來性高潮。更有趣的是，核磁共振造影中的圖像指出

to clitoral and vaginal self-stimulation, found that the same areas lit up when a woman

刺激女性的陰蒂及陰道在腦中所反應的區域，和刺激乳頭的反應區域

stimulated her nipples.

是一樣的。

Despite being an amazing source of both nutrition and pleasure, breasts are incredibly vulnerable.

雖然胸部是養育與歡愉的奇妙來源，但胸部其實是非常容易受傷的

Breast cancer is the most prevalent form of cancer in North America. Cells that divide

在北美，乳癌是最普遍的癌症。會分裂的細胞

often are at a higher risk of mutations than cells that don’t divide - and because breasts

所突變的機率往往比不會分裂的細胞還高，然而胸部

change and grow over the course of our lives, these cells are frequently dividing. The hormone

會因為發育更改變，所以細胞很常分裂。動情激素

estrogen also stimulates breast cell division, and there are environmental chemicals found

會刺激胸部的細胞分裂，再加上一些環境等化學物質

in pesticides, industrial products, and even our food that mimic estrogen and can influence

例如殺蟲劑，工業用品，甚至是一些仿動情激素的食物，都會影響

cell growth, increasing the risk of breast cancer. Research is discovering new risk factors

細胞生長並增加乳癌的風險。研究發現了一些新的可能造成乳癌的

of breast cancer such as breast density, age of first pregnancy, and genetic predisposition

原因，例如乳房密度、初次懷孕的年齡或是遺傳傾向性，

to breast cancer genes such as BRCA1 and BRCA2. This scientific knowledge can help increase prevention.

例如與遺傳性乳癌有關的基因：BRCA1和BRCA2基因，當然科學知識可以減少風險。

Although they are vulnerable, they are incredible, and regardless of shapes and sizes they are

雖然胸部很脆弱，但它們也是無懈可擊 的，不論是什麼樣形狀大小的胸部，

an essential aspect of sustaining human life and defining us as a species. Thank you boobs.

它們是延續人類生命的功臣，賦予了人類身為物種的意義。謝謝你，胸部！

Wanna learn even more about boobs? Check out our latest AsapTHOUGHT video where we debunk

想要學更多關於胸部的知識？看點進最新的AsapTHOUGHT影片，我們揭示了

some myths about Why Women Have Breasts. Click on the screen or use the link in the description.

「為何女人有胸部」的秘密。點擊螢幕上方或是簡介中的連結，

And subscribe for me weekly science videos.

並訂閱我們的每周科學影片吧！