Among the changes of consequence on the way from ape to human were the move to full bipedal locomotion, the marked increase in brain size and complexity, and the increased hand (i.e. forelimb) skills which this made possible, and, finally, development of the ability to make a wide range of sounds, convert them into meaningful speech and thence into complex language with an ever-increasing vocabulary - a progress which would inevitably have led to the creation of a written language. It is not certain when

these various abilities developed nor their order of succession, but there are suggestive clues.