Africa is the world's second-largest and second most-populous continent, after Asia. At about 30,221,532 km² (11,668,599 sq mi) including adjacent islands, it covers 20.4% of the Earth's total land area, and with over 900 million inhabitants in 61 territories, it accounts for about 14% of the world's human population. Modern human evolutionary theory recognizes Africa, particular the area in and around present-day Ethiopia, as the cradle of humankind.
The continent is surrounded by the Mediterranean Sea to the north, the Suez Canal and theRed Sea to the northeast, the Indian Ocean to the southeast, and the Atlantic Ocean to the west. It straddles the equator and encompasses numerous climate areas and is the only continent to stretch from the northerntemperate to southern temperate zones. Because of the lack of natural regular precipitation and irrigation as well as glaciers or mountainaquifer systems, there no natural moderating effect on the climate exists except near the coasts.