There are people that believe that the world's population started about 500 years ago. There are also people that believe, that according to the Bible, the world's population started over 2000 years ago with Adam and Eve.
Short, 5' would be tall. It has to do with a small piece of evolution, they were missing a lot of food nutrients. With more abundant food suppliers the generations keep getting bigger. But when the supply runs thin you know what happen to the dinosaurs.