A human hair consists mainly of a protein called Keratin. It also contains some moisture and the trace metals and minerals found in the rest of the body. 

    人類的頭發主要由一種叫角朊的蛋白質組成，并含有水分及在身體其他部分也可找到的微量金屬和礦物質。 

    The only living part of hair is underneath the scalp--when the hair had grown through the scalp it is dead tissue. 

    頭發唯一有生命的部分是在頭皮下面，當它長出頭皮時便成為無生命組織。 

    Hair’s natural shine is supplied by its own conditioner, sebum, an oil composed of waxes and fats and also containing a natural antiseptic that helps fight infection. Too much sebum results in greasy hair and conversely, too little sebum makes dry hair. 

    頭發的自然光澤來自它自身的護發素：油脂，它含有蠟和脂肪，還含有抗感染的自然抗菌劑。油脂含量過多會導致油性發質，相反，油脂含量過少則會導致干性發質。 

    Hair grows about 12 mm per month. If a person never has his hair cut, it would grow to a length of about 107 cm before falling out. Hair grows faster in the summer and during sleep. A single strand lives for up to seven years. 

    頭發每個月可長12毫米，如果一個人從不剪發，頭發會長至107厘米才開始脫落。在夏天和睡覺的時候頭發生長得較快。一根頭發的壽命可長達7年。 
    
    Healthy hair is highly elastic and can stretch 20 or 30 per cent before snapping. A human hair is stronger than copper wire of the same thickness. A combined strength of a headful of human hair is capable of supporting a weight equivalent to that of 99 people. 

    健康的頭發非常富有彈性，可拉長20％或30％而不斷。一根頭發比同等粗細的銅絲還要結實。滿頭頭發合在一起的力量可經得起99個人的重量。 

    Scandinavians normally have thin, straight, baby-fine hair, and mid Europeans hair that is neither too fine nor too coarse. People native to the Indian subcontinent have coarse textured tresses while Middle Eastern populations have strong hair. The hair of Chinese and Japanese people is very straight; that of Latin-speaking and North African peoples can be very frizzy and thick. 

    斯堪的納維亞人的頭發又細又直，像嬰兒的頭發一樣；中部歐洲人的頭發不細不粗；印度次大陸人的頭發粗且打綹；中東人的頭發都很結實；中國人和日本人的頭發非常直順；而拉丁語國家及北非地區的人頭發卷曲而濃密。