Why does our skin get dark and our hair get light under the sun?
In both cases, the sun breaks melanin, responsible for the color of hair and skin. The difference is in the fact that hair is not living, compared to skin. When the pigment is broken, it is not replenished in hair, so the latter gets lighter. Skin "answers" to the sun with a stronger replenishment of melanin, making the color darker.
Mansa Musa: the richest person to have ever lived.
Mansa Musa (about 1280 – about 1337) was an emperor (mansa) of the Mali Empire during the 14th century. He became emperor in 1307. He was the first African ruler to be widely known throughout Europe and the Middle East, and is regarded as the richest person to have ever lived. His wealth greatly surpassing anyone today.
Mansa Musa was the great nephew of Sundiata Keita, who was founder of the empire. He is famous for his Hajj (1324–5). His caravan was said to consist of 60,000 people carrying supplies and bags, 500 slaves each carrying a gold staff, and 80 to 100 camels each carrying 300 pounds of gold dust. On his journey, he is said to have given out millions of dollars worth of gold. He gave out so much gold in Cairo that the value stayed relatively low for many years.
After his Hajj, European cartographers began to draw Mansa Musa on maps. As the empire of Mali fell apart Mansa Musa's reputation did as well; he was no longer drawn as a noble king on maps, but instead more uncivilized. He was drawn as a parody of European royalty, and a normal person with a crown. Mansa Musa was married to Inari Kunate. Mansa Musa, at his time worth $400 billion, is still the richest man to date.