The two species came together again around 40,000 years ago, after the drought conditions subsided, and the combined population began a miraculous.recovery before expanding out of Africa to engulf the entire globe. Many anthropologists and archaeologists believe this era saw the beginning of fully modern human behavior, including abstract thought and complex spoken language. The big surprise was the length of time the populations were separate, believed to be the longest separation in our history.

The genetic study that arrived at these conclusions was conducted by the Genographic Project, a collaboration between National Geographic and IBM which started in 2005, and published in the American Journal of Human Genetics on April 24, 2008. The study concluded that mankind managed to survive this extreme depopulation coupled with the split as a species and still manage to reunite and thrive.

According to National Geographic, "The Genographic Project is a five-year research partnership led by National Geographic Explorer-in-Residence Dr. Spencer Wells. Dr. Wells and a team of renowned international scientists and IBM researchers, are using cutting-edge genetic and computational technologies to analyze historical patterns in DNA from participants around the world to better understand our human genetic roots. The three components of the project are: to gather field research data in collaboration with indigenous and traditional peoples around the world; to invite the general public to join the project by purchasing a Genographic Project Public Participation Kit; and to use proceeds from Genographic Public Participation Kit sales to further field research and the Genographic Legacy Fund which in turn supports indigenous conservation and revitalization projects. The Project is anonymous, non-medical, non-political, non-profit and non-commercial and all results will be placed in the public domain following scientific peer publication."

Amazingly, the information from the study is locked within the human DNA and reveals human history through the ages, ie.the study of anthropology using genetics. Specifically, this study used the mitochondrial DNA (mtDNA) of the Khoi and San people in South Africa. The mtDNA is passed solely from mothers to offspring, never from fathers. Because of this, the inherited mtDNA does not recombine with the DNA from the father and a linear path can be followed.

The original pioneering research using mtDNA was the 1980 study by Wesley Brown, then at the University of California at Berkeley, which traced modern humans to a single "mitochondrial Eve," who lived in Africa between what the researchers estimated as between 140,000 and 290,000 years ago. Brown's study found unexpectedly small differences among the mtDNA, signifying a relatively recent origin for modern humans. Brown's data suggested it would take 180,000 to 360,000 years to produce today's diversity starting from a single Eve.

Eve is our most recent common ancestor (mrca) following the mitochondrial lineage. Some people have confused "mitochondrial Eve" with the "biblical Eve", but this is not the case, as already stated, mitochondrial Eve is our "mitochondrial most recent common ancestor", the two clues here are "mitochondrial" and "most recent". There are more "ancient" common ancestors that lived before mitochondrial Eve. There were also a lot of other women alive at the same time as mitochondrial Eve (their mtDNA has not survived, either their female line died childless or at some point they produced only male offspring), although their "nuclear DNA" (which recombines with the fathers nuclear DNA) does survive. Therefore mitochondrial Eve bears no relationship, or proof of existence, of biblical Eve. The most recent estimate for the age of mitochondrial Eve is 140,000 years ago.

The male counterpart to mitochondrial Eve is "Y-chromosomal-Adam" and is similarly traced using the male only Y-chromosome, and not surprisingly, they did not live at the same time, Adam is estimated to have lived about 60,000 years ago.