Does anyone really believe this story? If so, you still live in a fairy tale world, although it doesn't sound like a fairy tale. If there is really only one man and one woman, then there is only one way for human beings to go, and there is no other way except extinction!
Why can't a man and a woman restore the population?
"Give me a woman and I can create a nation", which should be the rhetoric of many men. Actually, it can. According to the birth time of men and women, for example, a pair of men and women began to have children at the age of 18, and even separated triplets. Both parties may not have a company after 50 years old, but dozens of people should be fine!
But the biggest question is what to do next, because they are all brothers and sisters. Although there is no physical problem in breeding the next generation, they are all direct descendants. This kind of inbreeding generation has a very high deformity rate, and one man and a half women are lucky and disease-free. How to deal with the next marriage? The probability of such cousins or uncles and daughters matching the direct generation is not small, so within three generations, there will be many children who lack arms and legs, are stupid or have congenital diseases. Do you want them to breed the whole human race?
Why do close relatives get married and have children with genetic diseases?
In fact, consanguineous marriage is not uncommon in history, even after liberation, but it mostly exists between cousins. For example, Chen, the queen of Emperor Wu of the Han Dynasty, was also the daughter of her aunt Princess Guantao (cousin relationship), and there was a long-standing custom of close relatives sharing the same surname or even brothers and sisters marrying in the royal family of the Korean Dynasty.
The House of Habsburg
Medieval Europe was also exaggerated. In order to ensure the purity and nobility of the royal family, consanguineous marriage is popular. For example, consanguineous marriage is the biggest factor in the decline of the prominent Habsburg family. The last immediate successor charles ii had the most obvious genetic disease, and the curse of consanguineous marriage finally broke out on him. The last emperor was weak. Although married twice, but without children, the prominent Habsburg family went into decline!
The harm of consanguineous marriage
The simple understanding is that independent natural persons have complementary genes, and most of these recessive pathogenic genes will not appear, but the recessive pathogenic genes of inbreeding are basically the same, so the next generation will become dominant. If the next generation is still related by blood, the consequences will become more and more serious. Just like the prominent Habsburg family, no matter how noble the bloodline is, it can't stand the marriage of direct blood relatives.
Incidence probability of common diseases in consanguineous marriage
Therefore, in this case of only one man and one woman, the future is bleak. No matter how hard they try, they can't create a nation, and it will be extinct after several generations. The only thing that can save mankind is cloning, but it only increases the number of people in vain. It does not increase the diversity of genes, and future intelligence depends on cloning.
Only two people. How long will it take to restore the population if genetic diseases are not considered?
In fact, this is just a math game. Suppose a girl who gives birth to two twins at a time has a base of 2, and it only takes 33 generations to recover to 7.5 billion. If it takes 20 years, it will take 660 years. Of course, a large number of people will die in the past 600 years, but this is not a big problem, because the exponential growth in the future will be even more terrible, and the dead population will recover instantly in the last 660+20 years.
How many cardinality is needed to ensure the normal reproduction of the population?
If each offspring is accurately recorded and marriage is specified (the minimum probability of consanguineous marriage is guaranteed), then according to the normal population mortality rate and birth rate of 2 0.5, and men and women should rotate (who can accept it? ), then it takes at least 98 people to ensure that mankind will not become extinct. But if you want to get married freely without changing partners, it usually takes thousands of people. Of course, the more people there are, the best figure is about 5000- 10000 at the end of the month!
This is also the best numerical range for interstellar migration. To put it simply, if humans want to build a spaceship to fly to Kepler 452b, which is 1400 light years away, then this spaceship must carry at least 10000 people. Of course, it seems out of reach for mankind to reach this level now, but I believe it may be possible in the future!
Maybe the story of passengers will really happen then!