Early explorers in the Americas noted the use of geophagy amongst Native Americans, including Gabriel Soares de Sousa, who reported in 1587 of a tribe in Brazil using it in suicide,[5] and von Humboldt, who said that a tribe called the Otomacs ate large amounts of soil.[6] In Africa, Livingston wrote about slaves eating soil in Zanzibar,[6] and it is also thought that large numbers of slaves brought with them soil eating practices when they were shipped as part of the transatlantic slave trade.[5] Geophagia was common among slaves who were nicknamed "clay-eaters" because they had been known to consume clay, as well as spices, ash, chalk, grass, plaster, paint, and starch.[7]