Pondering the questions posed here by Scimitar and others concerning diffusion/hyperdiffusion I have, have had for some time, increasing concerns with the "out of Africa" scenario.
To imagine that one species- any species- can only evolve from one particular mutation, in one particular location, at one particular time........,is I think not only improbable..., but totally out of step with all the laws of the LIFE impulse; wherever LIFE has set foot on this incomparable planet it has done so with magnificent PROFUSION:
There is not just one spermatzoa that can fertilise the ovum of mammalian and other species in a single copulatory act- there are millions; there is not just one variety of any life form- bacterial, floral, amoebic, arboreous, marine, mammalian..., there are/have been, hundreds of thousands.
It would seem that wherever the footprint of LIFE has been able to establish a beach-head on this incomparable planet it has not left anything to chance....; it has in every diverse case loaded its magazines with enough firepower to overwhelm natural resistence to innovation.
So why...., when it arrives at this "pinnacle of creation"- you and I- written with a wry but not completely despondently sad smile, would nature elect to take a precarious punt on one solitary primate mutation in a rather inhospitable clime such as east Africa???
Why would it not ,if the evolutionary process can be accepted as viable- something that is as yet, far from a demonstrably proven 'fact of life'- not seek to mutate wherever appropriate earlier primate species have taken up residence; Sth America, Southern Asia??[ which introduces another uneasy spectre- how did those non-acquatic apes manage to negotiate those formidable oceans that separated them from their old folks home in Africa ]??
I leave you with one last thought:
Out of that 130,000yr timeframe in which all humanity is considered to have scampered off across the planet to take up residence in every nook and inhabitable cranny- according to those sepuchral powers that preside over these decisions while quaffing their late-night eggnocks- how is it that for instance the australian aboriginal, having arrived at his allotted territorial quota some 60,000yrs ago.., didn't take off like his antecedents and surf-ski across the Pacific to those fabled Americas[ or even Ancient Egypt which was going to be very big in the charts in due course ]?
Despite my occasional levity this is a serious post; I look forward to your response,