Objects could be brought before the eyes for minute examination. Ripeness of fruit could be judged by color changes. The need to remember seasonal changes in location and readiness of foods selects for survival of the smarter ones of each generation. As time passed, the forelimbs and forefingers were employed increasingly for handling food and objects of all sorts while the hind limbs became sturdier for supporting the body. Rest position was sitting upright, and even walking for short distances, carrying food became possible.
Bipedalism is quite common in the animal world.
They include all the cereal grains and even woody palnts such as papyrus and bamboo, over 4000 species in all. For a very long time they were scarce and had great difficulty in establishing themselves because of the unbroken forest cover. It seems to have been associated with movement of the tectonic plates. The forests were transformed in many places and open areas available for the establishment of savannah and prairies appeared. Nature abhors a vacuum, and presently some herbivores became adapted to grass-eating and great herds of grazers populated the rich grasslands.