There are two pieces to that ... clearly modern human (Homo sapiens sapiens) by the markers used for that identification, but by comparing mitochondrial mutations, there were a set of mutations shared with current African populations, a set of mutations common to all current African populations that are missing in Khwit's DNA, and additional mutations in Khwit's DNA not found in modern Africans. Mito mutations are added at a pretty steady rate, a sort of heartbeat, so by comparing what is shared, what is missing, and what is unique to Khwit & family, it isn't too hard to put a ballpark timeline of when their ancestors were last mixing genes with the folks who stayed in Africa.
We believed that the Sahara provided a substantial barrier to migration north out of Africa, but we are learning that not that long ago, 5000 years or so, that area was much more wet. Archeologists considered the Sphinx to be roughly the same age as the pyramids. The Sphinx shows some signs of water erosion not present on the pyramids. Indications now seem to suggest the Sphinx could be about twice as old and date to the time when the Sahara was tropical rain forest .. jibing with the erosion, perhaps. There's some indication that the Nile used to have a branch that went west quite a long ways and drained the area south of the Atlas (?) Mountains (sorry, my African geography is weak).
Anyway ... Zana/Khwit DNA could support paradigm shifts in our understanding of the "out of africa" migrations.