万物简史 第575期:生命的物质(1)（在线收听）

26 The Stuff of Life

第二十六章 生命的物质

If your two parents hadn't bonded just when they did — possibly to the second, possibly to the nanosecond — you wouldn't be here. And if their parents hadn't bonded in a precisely timely manner, you wouldn't be here either. And if their parents hadn't done likewise, and their parents before them, and so on, obviously and indefinitely, you wouldn't be here.

如果你父母双方没有在恰当的时间结合——可能要精确到秒，更有可能要精确到毫微秒，你就不会在这里；而如果你父母的父母没有在恰当的时间以恰当的方式结合，你也不会在这里；如果你父母的父母的父母，以及你父母的父母的父母的父母，以此类推下去，没有以同样的方式结合，显而易见，你也肯定不会在这里。

基因交换与组合

Push backwards through time and these ancestral debts begin to add up. Go back just eight generations to about the time that Charles Darwin and Abraham Lincoln were born, and already there are over 250 people on whose timely couplings your existence depends. Continue further, to the time of Shakespeare and the Mayflower Pilgrims, and you have no fewer than 16,384 ancestors earnestly exchanging genetic material in a way that would, eventually and miraculously, result in you.

时光越是倒流，你赖以降生的人的数量越是增加。仅仅上溯到8代以前，也就是查尔斯·达尔文和亚伯拉罕·林肯出生的时间，这个数目已经超过250人，他们双方的结合决定了你的存在。继续往前推，一直到莎士比亚和“五月花”号清教徒生活的时间，你有不少于16384个祖先，他们彼此的基因交换与组合，最终奇迹般地成就了你。

At twenty generations ago, the number of people procreating on your behalf has risen to 1,048,576. Five generations before that, and there are no fewer than 33,554,432 men and women on whose devoted couplings your existence depends. By thirty generations ago, your total number of forebears — remember, these aren't cousins and aunts and other incidental relatives, but only parents and parents of parents in a line leading ineluctably to you — is over one billion (1,073,741,824, to be precise).

在20代以前，这个祖先数目已增加到了1048576个。在此基础上再往前推5代，成就你的祖先数不会少于33554432个。而在30代以前，你的祖先的总数——记住，这些数目不包括堂亲、表亲以及其他更远的亲戚，而只是父母一父母的父母一直到你这一线——已超过10亿（确切地说是1073741824）。