A mutation that changes the incubation period (making it longer)? In the statistics of the incubation period (graph in post 20) there may have been some opportunities for such mutations. But there is no natural selection mechanism to pass on a long incubation period in Africa. People get their exposure through various stupid practices (e.g. hauling corpses in taxis), they get sick, and they pass it on, regardless of incubation period.
“(e.g. hauling corpses in taxis)”
There’s a good SNL skit in there, set in NYC. Would a corpse count as an extra passenger or luggage?