South African children attend a lesson by Katrina Esau, one of the last remaining speakers of a Khoisan language that was thought extinct nearly 40-years-ago, as she teaches her native tongue to a group of school children in Upington, South Africa on September 21, 2015. Tuu was once widely spoken around Upington and Olifantshoek in the Northern Cape province of South Africa, but was forcibly replaced by Afrikaans during the Apartheid years. In 1978, the language was declared extinct.  AFP PHOTO/MUJAHID SAFODIEN        (Photo credit should read MUJAHID SAFODIEN/AFP/Getty Images)