Agricultural Innovation in Africa: How to Feed 9 Billion. Calestous Juma, January 21, 2015, Video. "What is your solution for feeding the world? Calestous Juma's bet is on technological innovations in agriculture. The Belfer Center and Gates Foundation invite you to join the conversation that Bill and Melinda started and tell us your ideas for feeding the world. How? Post a video or simply tweet at @calestous or using #GatesLetter with your big bet to help feed the world. But first, go read the letter: http://gates.ly/agri2015." Link