English- and Spanish-speaking societies tend to be highly emotional and happy. Though the Anglophone nations of the world retain deep cultural links, it's not clear if Spain's emotional depth has anything to do with Latin America's. According to Gallup, "Latin America leads the world when it comes to positive emotions, with Panama, Paraguay, and Venezuela at the top of that list." Yes, even Hugo Chavez's Venezuela is apparently filled with happy people.
Africans are generally stoic, with some significant exceptions. The continent is among the world's least emotional, though there is wide variation, which serves as a non-definitive but interesting reminder of Africa's cultural diversity. Each could be its own captivating case study. It's possible that South Africa's high rating has to do with its cultural ties to Western Europe, for example, and Nigeria's may have to do with the recent protest movement in the south and sectarian violence in the north.