I have a few questions maybe a few of you can donate research and logic to. See, I lost my books for class and I'm broke so I can't buy them again. So basically I am answering questions from online resources. Questions are:

1. what are some major environmental challenges Africans face?
2. which areas of africa are most densely populated?
3. why is the term "tribe" inaccurate to describe different African cultures? what do african scholars say about the concept of "race"?
4. What are the major language families of African languages and where they are located?
5. why is the custom of polygyny declining in Africa?
6. what is the difference between segmental system of government and hierarchal form of government? What about pyramidal systems?

Thanks!