Humans are animals, so some of the characteristics of human society can also find similarities in nature. These include population topics that have been widely discussed recently.
Last year, foreign scholars published ecological research papers in the authoritative journal Nature-Climate Change, and they found that:
Some tropical songbirds in Venezuela and Malaysia breed less during the dry season, mitigating the effects of extreme weather on population continuation. Based on this, the researchers concluded that long-lived species will improve survival rates in extreme environments by adjusting breeding rates.
Spontaneous "family planning" in this animal is not uncommon, and in addition to tropical songbirds, there are typical examples of red foxes.
The red fox, which lives in Sweden, adjusts its fertility rate according to the amount of food it eats. When they find that food around them becomes scarce, they will reduce the mating scale of the population by half, and only half of the male red foxes can mate, while the other half of the male red foxes will disperse around the population, giving up the right to mate.
They know that in an environment of food scarcity, it is unwise to reproduce.
Moreover, the length of lifespan of species also seems to have some correlation with the level of fertility. For example, insects have a short lifespan, but they can produce a large number of larvae. The fertility rate of mammals with long lifespans is relatively low, which shows the fairness of nature.
It is the nature of every species in nature, including humans.
What is less well known is that aging and low fertility rates may be mutually reinforcing. The deepening of the degree of aging will reduce the fertility rate of the species, and after the fertility rate is reduced, the aging will further deepen, thus entering a vicious circle.
And it's all about striking a balance between population size and natural environmental elements such as food and climate.
In 2019, scientists found a giant bull mullet with a lifespan of more than 100 years in the northern United States and Canada, and through carbon-14 dating, they even found a giant bull mullet with an age of 112 years old, becoming the oldest freshwater fish.
However, according to scientists' statistics, these fish stocks were generally born around the 1930s of the last century, in other words, the breeding behavior of this group of fish has been suspended for decades, and it is the excessive "aging" that reduces the fertility rate of giant cattle cochineal.
It is worth mentioning that in controlling the size of the population, the decision-making of female animals is the biggest influencing factor of fertility willingness, and if natural conditions cannot meet the requirements of female animals, some animals will refuse to reproduce.
There is a red deer in Scotland, and when female red deer find that the population density is too large, resulting in a shortage of resources, they will delay their fertility.
There are also species such as voles and double-core grasshoppers, which will have fierce "intra-species struggles" to control population size when the population density exceeds the carrying capacity of the environment.
Someone once gave an image analogy, the so-called "inner volume" is the human world's own "intraspecific struggle", in essence, or between people in the struggle for survival resources.
Moreover, it seems that statistics also support such a thesis, and some scholars have published papers that believe that population density is the second important variable affecting fertility after women's educational attainment, such as the Nordic countries with low population density, which have higher fertility levels than Central and Southern European countries with high population density.