On a recent BBC documentary, I forget which one, they used genetics to somehow trace all human races and nationalities down their various branches to determine who was the most direct living descendent of the first human. It turned out to be a nomad living in tent somewhere in Kazakhstan. When the BBC film crew showed up to interview him and celebrate their discovery, they brought a doctor with them. When the man saw the doctor he was visibly disturbed because, as he said later, he thought that if the doctor brought such a crowed with him, it must be to tell him that he had some very serous disease.
I'm afraid that idea makes no sense at all to me. Aren't we all equally descended from the first humans? Who else could we be descended from?
I suspect they were probably trying to come up with the genotype closest to that of the first humans. If so, it seems highly likely to me he would be found somewhere in East Africa, where evolutionary pressures have probably been less diverse than elsewhere.