Since our galaxy was formed 13 billion years ago, and the earth formed 4 billion years ago, and since early man came to be about 4 million years ago--says 'Lucy' and the like in Ethiopia--, it stands to reason that man may have attained the present stage of evolution 1,000 times before. I have to smile at that one , myself. A billion is a thousand million.http://www.sciencedaily.com/releases/2015/12/151210095321.htm