Tim Harris 
Chimpanzees [PDF ebook] 

Why do some animals gather in family groups? How do they behave when they are in these groups? These and many other animal behavior questions are answered in these fascinating books. Chimpanzees are humans’ closest relatives-and the most intelligent. Baby chimps love to play. They learn very quickly by watching grown-ups and older brothers and sisters. When they reach the age of five or six, males run around in rowdy gangs.