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well, i can only add to this that in many Western Europian countries due to a process started by Napoleon that every person in a country was written down in the archives and therefore needed to give up a last name which stayed put from that point on. As many people from lower cultural levels (pretty much everyone except those who were of a noble family) didn't had a real surname, they gave up the names as they were known by in the neighbourhood. This could be their profession (John the Farmer), a reference to their father (John, son of James, i.e. Jameson), the place they were from (John of Barnaby) or a characteristic of the person which became identificable with him (John the Curly).
I know for example that in my country (the Netherlands) when you dig into your genealogy tree that at a certain you'll find that the surname change, like:

Piet Harms (Piet, son of Harm), his son's name was Jan Piets (Jan, son of Piet), his son's name Piet Jans (Piet, son of Jan). note: often firstnames are repeated due to the tradition of naming your son after your own father (i.e. the son is named after his grandfather).

Noble families are therefore the ones that you can dig into real far, up to 1200s, because those families where of importance and therefore their names are highly likely to be written on paper during history.