The DNA samples were compared with mitochondrial DNA extracted from the teeth of four ancient people: two skeletons aged 6,000 years and 5,500 years unearthed in an ancient shell midden on Lucy Island, and two skeletons aged 5,000 years and 2,500 years found on Dodge Island. Three living individuals had DNA matches with the older Dodge Island skeleton, and three of the skeletons matched at least one living person. That is a kinship covering at least 200 generations.
To be sure, it is not genealogy in the same manner that most of us think of when we start researching family trees. There is no documentation of the approximately 199 generations in between the living person and the ancient remains. Also, DNA only proves that the ancient bodies recovered are "closely related" to the living people but may not be direct ancestors. They could be aunts, uncles, or cousins to the living person.
Nonetheless, this is a fascinating example of DNA to further define ancestry.
You can read the full story in an article by Sandra Rimmer at http://goo.gl/7Cbqa.