Research shows that although people can reach and pick up objects when the use of only one eye is available, the accuracy and efficiency of the movement decrease as the distance to the object increases. Such research supports the view that binocular vision is important for .

The controlled use of fire by hominids: (a) limited the expansion of hominids into certain environments, such as dry grasslands. (b) decreased the amount of food energy available in the hominid diet. (c) contributed to geographical expansion and food production techniques in positive ways. (d) has been shown to contribute little to the digestive process of hominids.