I bet you do not carry stuff on your head. There is a close relationship between the way people carry stuff and their prosperity and human development. The more developed a people is the more they rely upon on something carry their stuff.
The very poor people can not afford those labor saving things such as hand-carts, wagons, bicycles, motor bikes, or cars. In a poor rural Congolese village, people carry stuff on their heads. Moving into a semi-rural or an urban city, you see a mix of carts, bicycles, motor bikes, and cars.
In Congo, I have never seen a ox, donkey, mule, or horse used to carry stuff. Animals compete against poor people for food.
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