Why multiple births are common in wildlife

This is the result of biological evolution, human beings are very well protected and nurtured for offspring, and the infant mortality rate is very low (relative to other organisms), while wild animals, the protection of offspring is often only for a short period of time (at birth), or even without nourishment and protection (especially lower organisms, including plants and microorganisms, such as roundworms, lay thousands of eggs at a time, as long as one survives, it is successful). Because they could not guarantee the survival of their offspring, they had to use mass reproduction to reproduce, which was just a survival strategy of the race.

Higher animals, such as us humans, and other primates, generally give birth to only one litter per litter, which not only wastes resources, but also ensures that all resources are invested in the upbringing of offspring.

Because human females usually only have one mature egg cell at a time, the chance of multiple births is very small, so it is uncommon for humans to have multiple births. And sometimes for some reason, it can also lead to the birth of twins.

This kind of polyzygonia is common in the biological world, and natural selection over a long period of time has made this phenomenon more conducive to the reproduction of the species. Therefore, in nature, the phenomenon of multiple births is very common.

This is the result of natural selection. According to Darwin's theory: the fittest survive, and the unfit are eliminated.

Originally, wild animals had both a small number of fetuses and a large number of fetuses. In the competition for survival in nature, there are fewer and fewer animals with a small number of births, and after many years, most of the animals with a large number of births remain. The competition for human survival is not too fierce, and life is very guaranteed, so there is no need to rely on the birth of multiple births to improve the survival rate.

In order to survive the population, wild animals can only start from two aspects: increase the birth rate and survival rate, and it is difficult to ensure the survival rate in the wild, so they can only make up for it by more birth, which is also the natural result of evolution.

The main difference is between an R-strategy (high risk, fast reproduction, short lifespan) and a K-strategy (low risk, slow reproduction, long life). Generally speaking, the more inclined the animal is to the r-strategy, the faster the reproduction, and the faster the reproduction rate, the more likely it is to have multiple births. Rats are R-strategic compared to humans, and aphids are R-strategic compared to mice.

There are some K-strategies, but there are many children born at a time in creatures that are at risk in young children's lives, such as sea turtles. Humans are social (able to guard against predators), use a variety of foods (gatherers and hunters are fairly well nourished, and rarely go to famine), and have good defenses, a stable lifestyle, low mortality rates, and easy to evolve a long-lived and slow-reproducing K-strategy. For R-strategists with high life risks and high mortality rates, the pressure of evolution tends to allow them to reproduce more to ensure the inheritance of genes.

On the other hand, the K-strategists are mostly large organisms, and individuals consume more resources, so they may face the problem of not being able to feed them. In addition, by the way, there is no necessarily relationship between the rate of reproduction and the level of reproduction. First of all, evolution is dendritic rather than trapezoidal, and there is no question of which is higher or lower.

Second, if human chauvinism defines "close to human" as "high", then there will always be some counter-examples. For example, bony fish are closer to us in the evolutionary branch than cartilaginous fish, but sharks generally reproduce less at a time than bony fish. Another example is that there are also tsetse flies (tsetse flies glossina), which only lay one maggot at a time, and there is ...... existSeek adoption.