Why did Picasso change from Realism to Cubism....

This is what I just wrote to a friend of mine on Facebook when she asked why did Picasso create the art that he did and not stick with Realism.... Cultural movements - The rise of Impressionism and the post impressionist movements of France and Italy, various teachers and inspirations such as Van Gogh, Degas. During the turn of the century, various new art movements started to happen such as Dadaism, Futurism, Neo-Reaslism, Called Pre-Raphealites along with German Expressionism all caught his eye. Then, around the 20's and 30's- 40's we started to uncover Colombian and other South American ruins and artifacts and as they started to make their way into our culture, Picasso wholeheartedly embraced their unique designs on masks and pottery and incorporated it into his works. Lines and forms for him started to change on his canvas as he strived to capture the primitive nature of the ancient cultures. The result was the mastery of a movement he mostly created called Cubism. Marcel Duchamp also had a major influence on Picasso especially "Nude Descending a Staircase" - 1911 (I believe) Amazing piece. All of these influences affected Picasso and he was Genius enough to understand what was going on in the world and paint the changes that were happening during that time. - Not bad for a quick response....