Answer:
Hominids
*Appeared 3 to 4 million years ago in souther and eastern Africa.
*Humanlike creatures called primates
*Mary and Louis Leakey excavated hominid fossils in the Great Rift Valley
*"Lucy," and Australopithecine fossil, found in 1974.
*Three major differences from earlier primates: bipedalism (gives ability to walk upright), a sizable brain (enables abstract thought and fine motor control), and a larynx (allows for complex speech)
*Thought-processing ability led to alteration of the natural environment to suit human needs
