May 16th, 2006 01:58 EST
According to Ashton, the point of the film was to tell the story of the movement of people, the origin of humanity, and the process by which we got to where we are now. Genetics help to tell that story.
Mitochondria are like small batteries that energize our body cells. They have their own DNA. The mother can only pass on mitochondrial DNA. This is because at the fertilization stage of the reproduction process, the sperm loses its Mitochondria when it enters the ovum.
Occasionally, the mitochondria undergo a small mutation that does not really affect anything. However, scientists can see and study it. When another mutation occurs, it simply covers the other one, forming layer after layer of mutation. In the event of a split in the mutation, it will be evident in the split in populations. When a mutation is carried along to a certain point, is evident in the population having a genetic characteristic that is unique only to that population.
It would be important to note that the mutation is in the mitochondria and as such has no effect on the physical characteristics of the population.
Stephen Oppenheimer, whose work was the basis for ‘The Real Eve’ Film, in his book Out Of Eden explains that genetic, archeological, and climatic evidence support the argument that all modern non-Africans originate from a single exodus from Africa of no more than a few hundred souls. These migrants had apparently been forced out of their homeland by increasing salinity in the Red Sea some 85000 years ago. All non-Africans today can then trace their mitochondrial DNA to one woman from this group, the Out-of -Eden-Eve.
According to Archeology, humanity came from the southern end of the Rift Valley in East Africa. Because of the genetic tracing, scientists say that everybody outside Africa carries a mitochondrial marker of one woman who must have been in a group of people who left Africa about 80,000 years ago. That group may have been group of anything from about 250 to 700 people. Popular thought suggests about 250. Less than 250 would not have been able to sustain a population and much more than 500 or 600 people would have taken too long for it to drift down to one line because they have to stay together. It has also been suggested that it had to be one group that left once. It was not a stream of people, groups leaving at different times, because the tracing leads to just one line.
The Genetic marker leads to one line. That line then became the ‘mother/Eve’ of everybody outside Africa. Then they started to split off. Some went down to Australia; some went up into Central Asia; some went up into Europe - carrying their own markers from that point. It is like the branches of a tree with the main trunk of the branch being in Africa.
Apparently, the real reasons for the exodus out of Africa may not be clear. Still from the genetic history point of view, all non-Africans can trace their origins back to Africa and one woman who left Africa 85000 years ago, and all humanity comes right back to what archeologists have come to call the ‘cradle of humanity’, the Rift Valley in East Africa.