Zindzi Mandela, the youngest daughter of South Africa's first black president Nelson Mandela and anti-apartheid activist Winnie Madikizela, has died at the age of 59. Zindzi died in a Johannesburg hospital on Monday morning. She was serving as the South African ambassador to Denmark at the time of her death. The cause of her death was not immediately revealed. Zindzi was the family member who read out Nelson Mandela's rejection of then-president PW Botha's offer for conditional release from prison at a public meeting in February 1985.