Many scientists believe that bipedal locomotion (walking on two feet) evolved in early hominids in response to the move from life in dense forests to life in open grasslands  Bipedalism would have allowed early hominids to see over tall grasses, helping them to locate food and to detect and avoid predators  However, because bipedalism also would have conferred substantial advantages upon early hominids who never left the forest -- in gathering food found within standing reach of the forest floor, for example -- debate continues concerning its origins
It may even have evolved, like the upright threat displays of many large apes, because it bettered an individual' s odds of finding a mate
Bipedal locomotion actually would not be advantageous to hominids living in open grassland environments.