Answer to Question 1
Nile
White Nile
Congo
Niger
Blue Nile
Zambezi
Orange
Answer to Question 2
Initially, according to the Pleistocene Overkill Hypothesis, it is likely they overhunted the megafauna (woolly mammoths, mastodons, and others) that existed in North America at the time of their arrival, although a rapidly warming climate about 10,000 years ago may have played a role as well. In later millennia, the Paleo-Indians' descendants made extensive use of fire to clear away brush, and in so doing changed many former woodlands permanently into grasslands. They domesticated numerous plants, and created modern corn by selectively breeding several types of maize.