Why are people tall in cold areas and thin in hot areas?

Personal feelings are still related to the living area and race, and now people's living standards are generally good. With the continuous supplement of nutrition, the height gap between the north and the south is narrowing, especially in the developed areas in the south, which is not shorter than that in the north. In fact, I think the main difference between north and south lies in shape. For example, the Northeast Tiger and the South China Tiger are different in size, mainly because they live in different areas.

First of all, the climate is due to the temperature in cold areas. It is easier to stimulate human growth hormone in cold regions than in tropical regions. People in cold weather will absorb more food and of course grow taller. Therefore, people in cold areas such as Russia and Yugoslavia are generally very tall. Of course, northern China is no exception. Followed by diet, rice and pork in the south are almost absolute staple foods. In the north, most people are used to eating pasta, beef and mutton. Of course, the influence of growth is different.

But these are not absolute. In recent years, the average height of Japanese teenagers has surpassed that of China according to Japanese statistics. That is, the higher the latitude, the farther away from the equator, and the colder the weather. People need to reduce and increase the body surface area of unit energy consumption, so northerners are very tall. Southerners, on the other hand, are shorter, because they are close to the equator and the weather is hot, so people should reduce their body surface area. In fact, it is not only human beings, but also other animals. The colder the same species, the bigger the local size, just like the Northeast Tiger is bigger than the South China Tiger, and the polar bear is much bigger than the tropical Malay Bear.

This is the result of ancient natural selection, and this phenomenon is also very consistent with Darwin's theory of evolution. In ancient times, because the conditions were not very good at that time, the cold areas in the north lacked heating equipment. I am in the south near the equator, and there is no refrigeration equipment in summer.

Both supercooling and overheating are easy to cause diseases. At that time, it may even lead to human death. People living at high latitudes, if only small genes. In cold winter environment, thin people are more likely to freeze to death. Those who survived retained the obesity gene. In low latitudes, hot and obese people are more likely to die of heatstroke, so thin people are more likely to survive in hot environments.