Birth of an Ocean: The Evolution of Ethiopia's Afar Depression

[rayofreason]

Formation of an ocean is a rare event, one few scientists have ever witnessed. Yet this geophysical nativity is unfolding today in one of the hottest and most inhospitable corners of the globe. Visit the site in safety through this extraordinary photographic essay.

http://www.sciam.com/article.cfm?id=birth-of-an-ocean

[hobbit709]

1. When the Rift floods, the birthplace of the human species will disappear.

[rayofreason]

2. It depends...

... what you call the human species.

The earliest find of Australopithecus afarensis was Lucy in the Afar, and if you say that bipedalism is the defining trait of humanity, then OK. Australopithecines were the first humans. If the defining trait is language, a la Steve Pinker, then the loss of the Afar is not necessarily the loss of the cradle of humanity.

[hobbit709]

3. Almost all of the earliest hominid fossils came from the Rift Valley

When the sea comes in at Afar, most of the Rift will be flooded not just the Afar region.

[rayofreason]

4. Actually...

... the earliest evidence of modern humans is in South Africa

http://www.sciencedaily.com/releases/2007/10/071017145252.htm

But you are correct that the Rift valley seems to be the birthplace of the hominids. So the point still stands - How far back along the line do you want to go to define human? If you mean our kind of hominid, South Africa seems the be the best bet right now as a cradle of humanity.