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.
● The only living part of hair is underneath the scalp--when the hair had grown through the scalp it is dead tissue.
● 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.
● Hair grows about 12 mm per month. If a person never has his hair cut, it would grow to a length of about 108 cm before falling out. Hair grows faster in the summer and during sleep. A single strand lives for up to seven years.
● 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.
● 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.
scalp [skælp] n. 头皮;战利品
antiseptic [,ænti’septik] adj. 防腐的，抗菌的;非常整洁的n. 防腐剂，抗菌剂
copper wire : 铜线
Scandinavian [,skændi’neiviən; -vjən] n. 斯堪的纳维亚人