San are not oldest people in world. Nor do they originate in africa.

[Prisoner Of Ice]

Interestingly, data supports san coming TO africa as easily as FROM africa.
http://dienekes.blogspot.com/2013/06/60-50-thousand-coastal-migration-to.html

And combined with this which shows lots of intermixing with eurasia, it's confirmed they had eurasian admixture before they got to africa (this is from populations with no exposure outside their little tribes until very recently, who remain pure).
http://dienekes.blogspot.com/2013/07/west-eurasian-admixture-in-khoe-san-via.html

[Caismeachd]

Why are they the closest people genetically to chimpanzees in that case?

[Prisoner Of Ice]

That's probably not true, and doesn't mean anything even if it is. Forested Nkongho-Mbo pygmie region is the source of y-dna A00, so called oldest human y-dna. Assuming its real source is not europe since that's where 9/13 samples came from. They just assumed they traced back to africa even though they were white.

[Caismeachd]

Yeah I've just read. Dunno. The genetic mutation/variation in Africa is much higher than any other area which is why most science assumes an out of Africa theory. They are just heavily mutated compared to us clustered Europeans and Asians. It's possible that if they were the first they would be the most genetically mutated/varied over time.