Demographic trivia: There is only one man and one woman left on the planet. Will the population recover?

Normally it is impossible, but something like this has not happened, and it is not alone. There can…

Normally it is impossible, but something like this has not happened, and it is not alone. There can be countless reasons for such a problem, but there are only one possible reason. Even if there is only one person, there is a probability of success. Technology can change the future.


Let’s talk about the impossible reasons first, and then give examples to refute and make up.

Minimum survival limit

Regarding the limitation of the number of individuals in the population, there are two models of biology: minimum survival population (MVP) and population viability analysis (PVA).

The minimum viable population (Minimum viable population), whose benchmark is the famous 50/500 rule, means that in order to prevent inbreeding, at least 50 individuals in a population are needed, and in order to reduce genetic variation erosion of the population, at least 500 individuals are required.

Demographic trivia: There is only one man and one woman left on the planet. Will the population recover?
Demographic trivia: There is only one man and one woman left on the planet. Will the population recover?

However, the MVP model does not calculate the random extinction caused by natural disasters, food, environment and genetics, but only by calculating the probability of avoiding inbreeding, the survival probability of inbreeding, and the survival rate of genetic variation, which is universal.

Population viability analysis (Population viability analysis) is more like a customized model. It is targeted. It is a simulation model based on MVP through computer technology. For example: to calculate a certain species, you need to add the reproductive capacity of the species. Inbreeding decline, birth rate, mortality, genetic variation data, environmental random events, historical climate change, ecological disturbance, etc.

Using PVA to estimate MVP, scientists can determine which biological parameters (such as hunting pressure, disease, habitat loss, inbreeding, etc.) will have the greatest impact on the extinction probability of a species.

For example, the results of the PVA model show that species with strong reproductive capabilities (such as arthropods and rodents) can adapt to lower MVP than species with weak reproductive capabilities (such as redwoods, large mammals, and certain birds). Sedentary trees usually have a higher MVP, trees generally have a higher age, and there are plenty of opportunities for reproduction. Some species inbreeding have a higher survival rate (such as elephants, vultures and cheetahs).

It can be seen that species are different from species, and the situation of inbreeding and survival is also different. We cannot treat all species with one criterion.

The miracle of inbreeding

Whether it is MVP or PVA, the minimum number of individuals in the population has not been calculated to be less than 30, even if high-level inbred elephants are no exception. However, the tenacious vitality of animals and plants in the real environment has repeatedly refreshed the scientists ’cognition. .

In 1788, the British brought 24 rabbits to Australia, but in the 19th century, the Australian rabbits had multiplied to 10 billion, and now the Australian rabbit has a headache, and even sent a bomber.

Moose is one of the second-class protected animals in China, and it is now full of moose on Newfoundland, Canada. The island and some countries regularly hunt moose. In addition to their fast reproduction and large numbers, another reason is that their large size often runs on the road and causes car accidents. However, the development of moose on the island of Newfoundland to the current scale of 150,000 was started from four animals introduced in 1904. Now in order to protect the growth of plants and prevent moose from eating, it is necessary to protect the forest with isolation nets.

In 1910, 10 moose were introduced into the New Zealand fjords, and 30 years later, some people have seen them.

There is also a marbled crayfish that subverts genetic diversity and causes geneticists to fall through their glasses. At some point in 1995, a genetic mutation enabled a marbled crayfish to reproduce asexually, and it began its journey to conquer the waters of Europe, Africa, and Japan. The key is that this cloning army has the same genes, but the adaptability and phenotype are very different. Rewriting genetic diversity to acquired diversity also allows biologists to discover a new continent in the biological world.

Human possibility

In fact, humans have more possibilities. We are different from other species. We have advanced wisdom and advanced technology. If the rest are two ancient Homo sapiens, then we will not talk about it. Needless to say, inbreeding does not breed, but survival is difficult to guarantee.

If it is assumed that all people are now emigrating to alien planets, only one man and one woman who can bear offspring are left behind, and the two are carefully selected, and it is possible to master the current human technology.

Survival and reproduction

Whether humans can continue to stand on the top of the earth again depends mainly on whether they conform to the sixteen-word core of evolution theory: excessive reproduction, natural selection, survival of the fittest, survival of the fittest, so some conditions are required to bless.

Survival depends on external causes: obtaining energy from the outside world, resisting external dangers, and adapting to the external environment.

Food needs to be inexhaustible and inexhaustible. In the early stage, a stable environment with no natural disasters in a short period of time, sufficient medicines and equipment, and sufficient weapons and ammunition are needed to deal with all beasts (this is also necessary, Recently, everyone is at home because of the virus, and animals have appeared on the streets everywhere. The news that the extinct animals reappeared shows that if the population on the earth disappears, the ecosystem will change dramatically).

In order to inherit the existing technology and science, all modern equipment and energy utilization and detailed scientific and technological information are also required.

Propagation is the internal cause: inheritance, disease, conflict.

First of all, these two people should start with genetic screening. There are no major genetic defects in the genes, and there are no bad recessive genes, so there will be no major problems in the early stage of inbreeding, and a sterile environment will be needed to protect them when they go out. To avoid external virus and bacterial infections, because of the lack of genetic diversity, this population is extremely vulnerable to certain unknown viruses.

With the above human beings, there are basically certain possibilities. Let ’s talk about higher-end ones.

With a certain number of people, we can learn the technology and equipment left by humans, and use gene editing, test-tube babies, and even ips cell embryo hybridization to create a cloning army.

If it was put in the past, when the origin of human beings, the probability must be 0, but now human science and technology have already glimpsed the secrets of life, and can detect life, modify life, and even copy life to a certain extent, so there is nothing impossible Even if there is only one person.

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