From the pages of Reach for Mars:

Ever since humans dropped out of the trees and started walking around on two legs, they have always looked up at night and gazed at the stars in wonder. Sitting at their fires outside their caves, as large creatures blundered around them in the dark, or eons later sitting at their campfires after riding the range all day herding and driving large creatures, who blundered around him in the dark, they would look up and gaze at the stars in wonder.