Hi Neanderthaler,
I won't try to write this in Afrikaans because my vocab and grammar are embarassingly bad!
Afrikaans is a derivative of Dutch. 350-odd years ago, a chap by the name of Jan van Riebeek landed with a few ships in Cape Town (or what was to be Cape Town) and colonised the Cape of Good Hope. This was mainly to establish the Duch-East India Company -- a trading and half-way post for ships on their way to trade in spices and other luxuaries from the East.
There is a story (I have no idea how true it is!) about a Dutch professor (who lectured on Dutch literature, I believe) who visited to South Africa and was appalled by what the Afrikaaners had managed to do to the Dutch language in only 300 years!
The reason, I think, for the Dutch / Afrikaans split was due to an amalgamation of several different cultures, including British, Prussian, and various other european countries who all had a vested interest in the Southern tip of Africa. I'm sure the Belgians were here too! After a while, the language was bound to change given all the influences and mergings that would have gone on.
Anyway -- I'm not a world authority on the subject and my family only arrived in South Africa 150 years after this -- and even then, to the East coast!
P.