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The East African Rif
A major breakthrough came on 17 July 1959, on the Leakeys’ seventh expedition to Olduvai. While Mary was walking her six Dalmatians she found a fragment of bone. It proved to be part of a mostly complete skull that was 1.75 million years old; it was nicknamed ‘Nutcracker Man’ because of its large molar teeth.
A further factor in the Nile’s importance was that it reliably flooded every year. During the late summer it broke its banks, depositing a rich layer of silt, fertilizing the soil and washing out salts. The Ancient Egyptians called the annual flooding of the Nile Akhet, and believed it was caused by the tears of the goddess Isis weeping for her dead husband Osiris. The true cause of the inundation, though, was monsoon rainfall hundreds of miles upriver in Ethiopia, which caused a surge in the volume of water that eventually led to flooding of the Nile in Egypt. The floodwaters sat in natural basins that formed an immense reservoir of water for farming during the six to eight weeks when the river was in flood. These natural basins were added to by a complex system of dykes and irrigation canals that allowed the water to be stored and distributed more effectively.
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