There is also now the assertion that the reduction in phonology as you move farther away from Africa points to a common ancestor.
I've coupled this observation, which I feel actually demonstrates that the ancient peoples who left Africa didn't have the phonological diversity that later developed in Africa, with the findings that Aborigines in Australia represent possibly the oldest people and culture outside of Africa itself.
I put it all together and argue in this video that traces of the original human language can be recovered.
What words from the original Proto-Human language might have survived in three major language families for 70,000 years?
Fire, eagle, and dead.