[parabyl]

Blanking on a source right now, but I recall reading about a study on the 'oldness' of languages and found that the unique sort of phonetics in !Kung and other Khoe or San languages appeared to reduce over time, and simpler hard consonants would emerge in their place - implying that they are indeed some of the oldest languages still around.

Interstingly, there are a number of words from these languages that are still widely used in South African slang: Dagga for Marijuana, Eina for "Ouch!", Gogga for Bug or Insect, and Kerrie for Stick, usually used as the neologism Knobkerrie. Very possibly some of the oldest slang in the world!