|by Stephen Oppenheimer
The southern route out of Africa - the second and only successful exit - was at the southern end of the Red Sea, an isthmus 25km wide and 137 metres deep, known as the Gates of Grief [Bab al Mandab] from its numerous reefs.
A southern route across the Red Sea which is most accessible when the Earth is glaciated goes some way to explaining the mounting evidence for our own defining exodus 85,000 years ago from Africa.
The strait was very much narrower during glacial periods, allowing easy island-hopping across the shallows and the reef islands of the Hanish al Kubra, at the northern end of the isthmus. Measurements made on the Greenland ice cap show that the second coldest time of the last 100,000 years was between 60,000 and 70,000 years ago. At its coldest, 65,000 years ago, this glaciation took the world’s sea levels over 80 metres below today’s levels. Certainly a stimulus to move.
Perhaps dwindling food resources on the western shores of the Red Sea, attractive beaches on the Gulf of Aden, and cool wet Yemeni uplands for refuge were what spurred our ancestors to take their momentous step.
|Single Mitochondrial DNA Line - Out of Africa
All non-Africans belong to and are desended from the African L3 line. The dotted line in the diagram below indicates the Out of Africa L3 Eve at the Gates of Grief.
descending from 1 to 16.
The figures above represent the 15 surviving African maternal mitochondrial lines older than 80,000 years. From those fifteen lines only one mitochondrial line would, over many generations, become the Out-of-Africa Eve line, or the common ancestral mother line of the rest of the world. This random selection and extinction process is called genetic drift because the original mix of lines has drifted towards one genetic type.