The mainstream view is that climate change is the main driving force of human biped walking  Millions of years ago, the area of forests in Africa began to shrink and the area of grasslands increased greatly  In an environment with few trees, the significance of biped walking is clear: standing up allows human ancestors to look beyond the lush grass to see predators and prey
In the area where early bipedal walking human fossils were found, a large number of contemporary forest animal and plant fossils were also found
 As a result, the massive increase in the area of grasslands has made the ancestors who are the most good at standing more likely to survive and pass on their genes