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Man is dying?
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这是我上星期在toast master上的5 minutes presentaion作业，学生物的专业人士请勿笑话。
本文改编自饶毅在2月19日《南方周末》上发表的文章《男子汉：基因本质及灭顶之灾》。别人给的
两个comment:
1. Oh, man is a production with bugs, since Y is being error-coded!
2. I guess the reason why there is more man in the world than women is, the chromosome Y is much smaller, thus it is easier to produce a Y.

Man is dying out as a kind of species

Good afternoon, guys. I am going to talk about an astonishing topic, that is,� (writing on white board � �MAN is Dying�) �Man is dying out as a kind of species�.

How could this happen? Let me explain it.

Long long ago, human being evolved to male and female. Although human was distinguish as male or female since thousands years ago, the mechanism of the sex was only found in 1959. In that year, the structure of DNA was discovered. (Have a poll) How many do you know DNA? Raise you hand if you do NOT know. DNA is a kind a matter existing in every cells,� and the DNA which can bring the gene information is called chromosome(write down chromosome and explain the pronuciation to audience). Every normal human have 46 chromosomes, and 44 of them have no relations with sex, the rest 2 chromosomes is a couple, which decides the sex gender. The last 2 chromosomes can be X or Y. Female have two X, and� male have one X and one Y.

Scientists have discovered that the Y is a selfish gene. The only task of Y is to reproduce itself. Chromosome Y is important to itself, but has no contribution to the group of chromosomes. The body will present to male if only Y exist, the existence of X is ignored at this case.

Chromosome Y is not team-working. Each group of chromosomes can exchange their information, but Y do not exchange their information with X. It is very important to chromosomes to exchange their information, the damaged gene sections can be wash out in the exchanging procedure. With information exchanging, chromosomes keep their energy to survive. But Y refuse to exchange with X because it want� to keep its unique information as a male. The result is, Y can not fix the bugs in the reproduction, thus the damaged sections� have to be deleted from the chromosome. So the chromosome Y of modern man is much smaller than X now, even they used to have the some size. Nowadays there are 1500 genes on X, but less than 100 genes on Y. If the trends continue, Y will disappear some day, scientists forecast Y will die in no more than 10 million years.

What could happen if Y really dies? Could all the guys sitting here is female? How could human being reproduce themselves? Scientist said that would not be a question. First, no one can tell if human being can exist for another 10 million years. Second, chromosome Y was evolved from X, since there is two X on female, one of the X chromosome may evolve to distinguish the sex gender. However, at that time, human being could not be called by human being, because they are in a different species from us.

posted 2004.03.08 Monday