The average life expectancy of Africans is very short, because, first, the medical conditions in Africa are very poor, and only large cities have medical institutions. Second, African people are generally poor. When they are sick, they have to put up with it hard. If they can't bear it, they will fall. Third, Africa has poor hygiene habits, drinking raw water, eating raw meat, not taking a bath for a long time, and there are many bacteria and viruses. In the final analysis, it is still poor. This is what I saw.

The reason why African blacks run fast:

Studies show that black athletes' fast muscle fibers account for more than 80% of the muscles, while whites and yellow people only account for 70%. From the point of view of muscle mechanics, there are more fast muscle fibers, the degree of flexion and extension of muscle contraction is greater, and the explosive force will be stronger. At the same time, muscle fibers are divided into red muscle and white muscle according to different colors. Red muscle cells have more mitochondria and provide more energy, so people with red muscles or mainly red muscles belong to explosive players. White muscle cells can provide energy evenly and continuously, so people with white muscle or mainly white muscle have stronger endurance. The muscles of black athletes are mainly red muscles, so they are more suitable for sprint events.

In addition, black players have hard bones, can withstand greater impact, and have slender limbs, narrow hips and less fat, and are superior to other races in body stretching, coordination, flexion and extension. Bolt's body shape can well reflect these characteristics: long limbs, sufficient strength and good high-speed endurance.