Kenyan Wangari Maathai became the first African woman to win the Nobel Peace Prize in 2004. She was an environmentalist and human rights activist who founded the Green Belt Movement in the 1970s. She focused on the planting of trees, conservation, and women's rights but repeatedly clashed with the government while trying to protect Kenya's forest and parks. She was arrested and beaten on several occasions. Witness speaks to her daughter, Wanjira Mathai.

(Photo: Kenya's Wangari Maathai (L) challenging hired security people working for developers in the Karura Forest, in Nairobi, Kenya. Credit: Simon Maina/AFP/Getty Images)