Why are southerners generally shorter than northerners?

According to the existing research results, 60%-80% of the height difference is determined by genes, and the remaining 20%-40% is attributed to external factors, that is, "seven points are destined by heaven, and three points depend on hard work." Height is closely related to heredity. Generally speaking, if both parents are tall, the children will not be short. External factors mainly include climate, diet, sleep and so on. This also caused the height difference between the north and the south.

German biologist Karl Bergman's "Bergman's Law" holds that for the same warm-blooded animal, the colder the place, the larger its volume. At the same temperature, the larger the volume, the slower the heat dissipation. Because people's skin has a great heat dissipation function, people living in the tropics have more heat dissipation, and living in the cold zone has less heat dissipation, which will help warm-blooded animals regulate their body temperature. The northern latitude is high and the temperature is cold. In order to reduce the loss of unit energy, it is necessary to increase the body surface area. So northerners will grow very tall and big, while southerners are just the opposite.

There are more plant-based foods such as vegetables and fruits in the south, while in the north, there are more foods based on carbohydrates and meat. In modern society, there is not much difference between North and South people in fruits and vegetables.

The amount of growth hormone secreted by the body has a great relationship with sleep habits. Generally speaking, there are two key points: first, the secretion of growth hormone at night is much higher than during the day; 2. There are more growth hormones in the first half of the night than in the second half of the night. The two periods with the highest overnight growth hormone secretion are 22:00-2:00 and 5:00-7:00, accounting for about 90% of the night growth hormone secretion, and the peak is 23: 00- 1. Undoubtedly, the sleeping habits in the north are more conducive to the secretion of growth hormone.