The mitochondrial DNA, or mtDNA, is a loop of DNA that is passed from mother to child in every generation. Geneticists have been exploring the intriguing information about mankind's past contained in this molecule to attempt to determine how much changes had occurred between the DNA of the first human mother (named “Mitochondrial Eve”) and her offspring today; and also to deduce how long ago was she here on earth.
Like every dating method, there must be some inherent assumptions, especially with respect to the rate of change in the physical process being used. In this case, the rate of mutation in the DNA is central to arriving at a date for Mitochondrial Eve. However, according to an article published in the evolutionary journal Science in 1998, evolutionary scientists had to reject the clear evidences suggesting a new mutation rate than what was being used at the time – the reason being that the clear scientific evidence “did not make any sense.” In the words of the writer: “Regardless of the cause, evolutionists are most concerned about the effect of a faster mutation rate. For example, researchers have calculated that "mitochondrial Eve"--the woman whose mtDNA was ancestral to that in all living people—lived 100,000 to 200,000 years ago in Africa. Using the new clock, she would be a mere 6000 years old. No one thinks that's the case..”
ICR’s Brian Thomas concludes: “So, to align the age with current evolutionary theories of human origins, subsequent calculations have started with assumptions that ensure at the outset that Mitochondrial Eve would have lived more than 100,000 years ago.”
But the best available data being obtained today are still most consistent with the earlier studies that showed that the age of Mitochondrial Eve coincided well with the biblical age of the historical Eve.
For example, a 2008 study of the mitochondrial chromosome found that, quite surprisingly, only 21.6 nucleotides - out of 16,569--DNA differences exist between modern DNA and the consensus DNA for Eve. Going by what is known about mutation rates over the years, according to Brian Thomas, this clearly indicated that “ a much shorter time than "200,000 years" must have transpired since Mitochondrial Eve arrived on the scene.” (For details and references, see http://www.icr.org/article/mother-all-humans-lived-6000-years/)