Hair comes in many varieties and its colour and thickness are determined by genetics, but we all have roughly the same number of hairs on our bodies.

Hair comes in all colours, lengths, and thicknesses and it can be straight, slightly kinked, or very curly. Hair type is mostly determined by genetics, whether it is of animal, or human origin.

Geneticists have discovered that some physical characteristics of human hair are dominant, which means that they are more likely to be passed on to children. The characteristics that are less

likely to be passed on are called recessive.

Dominant characteristics include curly hair, dark hair, non-red hair and recessive characteristics include straight hair, light hair, and red hair.

So a child is more likely to inherit dark, curly hair from either parent than straight, light coloured, or red hair from either parent. Obviously, if both parents have any of these characteristics

the odds of inheritance become much higher.

Both men and women have a total of around 5 million hairs on their bodies. These may be dark and easy to see, or so fine that it is difficult to see them with the human eye. Even bald-headed

people have minute hairs on their heads.

Fair-haired people tend to have slightly more than the average and redheads slightly fewer. The only parts of the human body that are totally hairless are the lips, the palms of the hands, the

soles of the feet, the sides of the toes and fingers and the upper part of of the ends of fingers and toes.

Hairs are dead from the root upwards but the 100,000 or so hairs on the head grow at a rate of 10mm, or 0.4 inches per month with a slight increase during the summer months. That's an amazing 4.8

inches per year.

Contrary to popular belief, cutting hair does not make it grow faster, or slow it down. Thickness varies according to hair colour and redheads have thicker hair than brunettes and blondes.

Most people lose and replace about 100 hairs per day, but hairs can remain in the same follicle for up to six years.

Stories are often told about people finding that their hair has turned white over night when they have had a fright, or sudden shock. This is not true and what happens in these cases is that the

coloured hair actually falls out and it leaves the white hair behind. The person may not know that they had any white hair before because it is often hidden by the coloured hair.

头发有许多的种类，它的颜色及密度是由遗传决定的，但是我们身体上毛发的数量都是大致相同的。

头发有不同的颜色，长度及密度，它可以是直发，微卷或是大卷。不 管是动物还是人类，头发的类型绝大都是由遗传决定的。

遗传学家发现毛发的一些物理性特征是占主导地位，这就意味着它是可能遗传给下一代的。一些可能很少被遗传的特征叫隐性特征。

主导性的特征包括卷发，黑发，非红色头发，而隐形包括直发，稀疏毛发及红色头发。

所以比起从父母那遗传直发，稀疏毛发或红头发，孩子更容易遗传父母的黑发，卷发。显然，如果父母双方都有任何一些这些特征，遗传的几率将会更大。

不管男人还是女人，身上的毛发大概有5百万根。这些可能是黑色毛发，肉眼可看到的毛发，或是肉眼无法看到了毛发。甚至秃头的人，在他的脑门上依然有细小的毛发。

金发的人身上的毛发略多余平均数，而红头发的人会略少于平均数。人类身体上完全无毛发的地方是嘴唇，手掌，脚底，脚拇指和手拇指缝及手指和脚趾的末端。

毛发是从根部向上先死亡的，但头上大概1万多的头发在夏天大概以每月10毫米或0.4英寸的长度慢慢长长。即每年4.8英寸的数度增长。

与大众的想法不一样的是，减发不会让头发长的快或长的慢。头发稠密的不同是因为头发颜色的不同。红发人的头发会比黑发或金发的人更加稠密。

大部分的人每天要掉100根头发，也会重新长出100根头发，但是头发可以保留在小发囊里长达6年。

故事中常常有说某个人的头发因为惊吓或是突然震惊而一夜间变白。这不是正确的。发生这样的事，是因为有颜色的毛发脱落，只剩隐藏着的白发。这些人可能不知道他之前其实有白头发的，因为往往白发会被有颜色头发所掩盖。