Bipedal Evolution

Natural Selection in my oppinion led to bipedality in our ancestral hominids due to changes in the environment over time.  The use of tools and counting found in caves fossils dated thosands and thosands of years ago, show that the environment made it necessary for our ancestors to stand upright, perhaps, to hunt because the foliage was too higher up in the tree canopies or to catch other vetebraes to eat.  For early hominids they needed for "Natural Selection" to make their brains larger to combat the elements, and perhaps because of "Sexual Selection" for monogamy among pairs of the opposite sex.
In Ar. ramidus, the earliest hominid recently discovered in 1994 in Eithipoia.  The scientists had to stop the digs for the fossil remains for years due to floods in the wash area and local warfare between tribes.  But, they went back to their dig for Ar. ramidus in the early 21st century and in the last year and half the scientists have made many concrete theories.  The test were conducted on the fossil remains of Ar. ramidus of jaw bone pieces and teeth, libs, and a partial femur.  The current studies have shown that this is the oldest most recent ancestor to Homo sapiens.  The scientists also believe that Ar. ramidus walked upright and that the current drylands where their remains were found recently used to be a forst-like and some grasslands (Lovejoy, and "Ardi" television show, 2009).