Just like the history of Greece. Greek newborns must be examined by the elderly when they are born. If babies are healthy and strong, they will be left behind and unhealthy babies will be thrown away.
This practice is the bloodiest embodiment of survival of the fittest. All this is to ensure the long-term population advantage and win the battle for the city-state.
Extended data
About physique
Black people are quite strong, probably because most of Africa exists in the form of tribes and has existed for many, many years. When they existed as tribes, they could only make a living by gathering and hunting. There are many dangers on the African continent, not only lions in groups, but also various fierce carnivores such as vultures and hyenas.
If they want to survive in these animals, if they want to hunt them to fill their stomachs, they must be strong. Perhaps it is for this reason that black people appear to be very strong.
Baidu encyclopedia-black people