I think there is an interesting implication to this that wasn't discussed in the article. All modern humans can be traced to one small group of humans and if all human language can be traced to that same group then that would lead us to believe that language existed before before modern humans. This group must have had splinters break off fairly early on and they must have already had language or they would have developed though own. I guess it is possible that the did break into smaller groups with unique languages after they had developed into modern humans but only one group survived. That seem like an unlikely scenario since I doubt there was one magic moment when we went from being animals with no speech to full modern humans.

I do have a couple of issues with the concept though. One part of the article states that some African languages have 100 phonemes and this is the evidence that they are older. But it also states that the more people who speak a language the more phonemes there are and English only has 45. Even if you go back to old English did less people speak old English than spoke some of these south African tribal languages? This seems odd to me.

I also have trouble understanding the mechanics of why this would happen, why geographic distance from the origin would affect the development of a language. If you have two groups that split and one of those groups moves away why would that affect how their language developed? They both spoke the same language and then one day a group said "fine you stay here we are going to look for food in that valley". Why would the language of the group that moved change in a predictably different way than the group that stayed? Not saying it isn't true but I would like to know more about what they think would have caused this shift.