Simplify the following text for a Grade 7 native English-speaking person.
Original: Her thesis was completed in 1965 under the tutorship of Robert Hinde , former master of St. John 's College , Cambridge , titled `` Behavior of the Free-Ranging Chimpanzee , '' detailing her first five years of study at the Gombe Reserve .
Simplified: Her thesis was completed in 1965 , titled Behavior of the free-ranging Chimpanzee . It told of her first five years of study at the Gombe Reserve .