Why do n’t humans have long hair, and why people at high latitudes have not evolved thick hair to protect them from the cold?

2020-01-10 | Scientific Beauty Boy original |

Why humans fade thick hair

Humans were originally hairy. 30 million years ago, plate movements gradually formed the rift valley in East Africa, and the forests in the east of the rift valley gradually became grasslands. With the reduction of trees, arboreal apes were forced to start 4.5 million years ago.Life on the ground, scientists call this earliest ape a monkey.

1974, humans discovered the "human grandmother", the southern ancient ape fossil named Lucy. Based on the fracture site of this southern ape, it was judged that it fell from the tree and was injured and died, indicating that the southern ancient ape was still alive.He lives on a tree without a tree. Scientists have found that its pelvis and leg bones function almost the same as modern humans, showing that this ancient ape can walk upright.

2 million years ago, Homo erectus was born, they have completely separated from the trees and live on the ground, and their brain capacity has doubled compared to the southern ancient ape, reaching 1000 ml. The history of human evolution, hereBefore, there were still thick hairs.

The Homo erectus learned how to use fire and make stone tools through the accumulation of ancestors, greatly amplifying his own ability, at the same time improving the energy acquisition efficiency and absorption efficiency, having the ability to migrate, and began to leave the highly competitive Africa to the worldMigration. Beijingers, Yuanmou people, and Lantian people are the remnants of this great migration. Some scientists have analyzed the geographical isolation time and reproductive isolation time of head lice and pubic lice through the molecular clock effect, and concluded that humans are in 1.2 million years.Thick hair that had faded before. And scientists found through fossils that more than 70,000 years ago, when Homo sapiens walked out of hot Africa for the second time, they had put on sewn animal clothing.

East African steppe under the scorching sun

Located on the equator, the grassland is endless, the trees are dotted, and large animals are hiding under the tree to enjoy the cold. Imagine: under the hot sun, if a group of people wear mink coats and mink pants are chasing prey wildly on the prairie?

Large predators are sprinters

Often you can see in the animal world that even large animals can't be hungry, they must hunt their prey when the sun goes down. Because on the African savanna, most predators are sprinters, we often sayHow fast can cheetahs run? Has anyone heard that cheetahs and lions can travel thousands of miles. Large carnivores generally have sharp teeth and sharp claws that can hold the prey's body tightly. Instantly,Life and death are judged, especially the lion's success can only be achieved with a single blow. If a single blow fails, the sprint distance is generally not more than 100 meters. The lion is too lazy to run even 100 meters.After each sprint, you will gasp in a big mouth and violently contract your abdomen to dissipate the huge heat generated by the instant impact as soon as possible.

Endurance Hunting

Animals are still like this, upright people do n’t have claws or sharp teeth, let alone speed. In order not to starve, humans have learned a skill that animals ca n’t do—marathon hunting. As the name suggests, they keep running until theyThe prey chased and froze to the ground, and fell to the ground. Now some ancient African tribes, American Indians, and Aboriginal Australians continue this marathon hunting method.

Running a marathon under the scorching sun, this is something that animals in East Africa ca n’t even think about, but erect people can. This ability is that lion and cheetah are scared when they encounter it. Because they ca n’t run for more than 1 km, their bodiesWill die because of heat and heatstroke.

We can imagine that an upright person did not have thick hair when he was born because of a genetic mutation. He lives more comfortably on the grassland than other uprights. As he reproduces, he will extend many non-hairy offspringBecause of their strong heat dissipation ability, they can run long distances. They have easier access to food, better survival and stronger physique than others. They have changed from gathering to hunting, and the absorption of meat nutrients has also promoted their brain development.Larger brain capacity. Fading hair is not only a superficial evolution, but a series of reactions that follow, more beneficial for survival and development. From the perspective of energy, it can be said that if the body hair is not fading, the birth of Homo sapiensIt will be a long time later.

Why people at high latitudes don't have long hair

A baby was born in a white American family in 1983, and her birth really surprised her parents because she was the longest-haired person in the world.

Mao people have also appeared in China many times. Yu Zhenhuan, a Chinese hair child born in Xiuyan County, Liaoning Province on September 30, 1977, was recorded by Guinness as "the person with the most hair in the world".

There are many similar examples at home and abroad, why do most people not grow up? Because for the time being, long hair is more disadvantaged than advantages for human beings. From an aesthetic point of view, this needless to say, unless there is a habit in this area.From the perspective of efficiency: think about it is troublesome for men to wash their short heads every morning. If they are covered with hair, they ca n’t leave the house without tossing for 2 hours a day.It will be even hotter.

In fact, there is no advantage for people at high latitudes, and humans are not living in the wild. We are now living in houses. Like cold Northeastern people go out. "Big cotton jacket and two cotton pants. This is our labor protection, leather.Inside the hat, cotton gloves, and vest, there is a mink. "Cold wear, hot take off, is more conducive to human health, more conducive to survival, more conducive to reproduction, you can rely on regional climate adjustment at any time to better adapt to natural selection.

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