The Salt Lake Tribune reports on "theorizing" involving the East African Rift Valley uplifting and evolution. Quoth the story:
University of Utah geologists have devised a tectonic-based theory that supports this idea by linking massive uplift in east Africa with local climate changes that helped jump-start early human evolution.
"Most of the uplift occurred between 7 million and 2 million years ago, just about when hominins split off from African apes, developed bipedalism and evolved bigger brains," Royhan and Nahid Gani state in an article in the current edition of Geotimes, a magazine of the American Geological Institute.
Of course, carefully left out the story is the unexpected arrival of Sahelanthropus tchadensis, WAY OVER in Chad, which seems to be a pretty good candidate for hominid status at 7 mya and is nowhere near the rift valley. The split dates have been needing revision for some time now. 7 mya just doesn't cut it anymore.