The evolution of words are often derived from corrupted transcriptions throughout history. For example, the word 'zenith' is a corruption of an Arabic word starting with 'sams ... ' but sounds nothing like its origin. It is understandable why this occurs, because few people were around at the time to make literacy widespread and the few scholars who wrote down the texts oftentimes made mistakes when copying it for the rest of the populace. So when people say that language still evolves today, there are only a few new words every once in a while that are essentially invented on the Internet, where jargon culture is rich and profuse. However, it will never be the same as in the older times when a mistake was successfully propagated and accepted as such. Mistakes today will be recognized as such, and corrected back into orthodox fashion. I feel that the biological concept of evolution is similar for humans. Humans had plenty of room for certain types of natural selection to prevail before the agricultural (and to a lesser extent, the Industrial) revolutions. However, because there are so many humans today where the physically weak can often survive through intellect, evolution will not bring about major changes. People will not grow tails or leap higher. All mutations are not robust, unlike earlier-developed ones like lactose intolerance, blue eyes, or sickle-cell anemia.