The ancestors of modern human apes could walk upright three million years ago.

As everyone who isn't an uneducated moron knows, we share an ancestor with the modern chimpanzee apes. Our common ancestor split into two lineages about six million years ago. One lineage evolved to become modern chimpanzee apes and modern bonobo apes. The other lineage developed into modern human apes (and a few other human-like species that went extinct).

What's interesting is the lineage that developed into chimps evolved just as much as we did. They just evolved differently to be able to survive in their different environment which was living in trees. The environment of our ancestors was not in the forest. Any mutation that helped us survive better in that environment was selected for (creatures who had what it took to survive passed their genes on to the next generation). The changes were gradual. For example the fossil evidence shows a gradual increase in brain size.

Several features developed in our ancestors to make walking upright possible, which was very helpful in our treeless environment where it was necessary to run fast to hunt for food. We were predator apes and that's how we survived.

A three million years old fossilized foot bone shows that our ancestors had arches in their feet which is evidence they could walk upright that long ago. The ancestors of chimpanzees were better off with more flexible feet to climb trees, so that feature was selected for. This is an example of how both lineages evolved in different ways to adapt to different environments.

MU researcher helps change view of human evolution

This is just one of countless examples of how interesting the history of life is. The evolution deniers don't know what they're missing because they're too busy praising their dead Jeebus and flying airplanes into buildings.