This Part discusses the results of that descendant's mtDNA testing.
The DNA of Carol Anne Baker, a maternal descendant of Jemima Campbell, was obtained using the normal "cheek swab" and analyzed by Family Tree DNA using their “Full Sequence” test. [That test includes HVR1, HVR2, and Coding Regions.] Her results were then compared with others to determine common ancestors.
Mutations in certain parts of the DNA are common to many participants. Those common mutations happened thousands of years ago and the date and location of some mutations can be estimated. Of course a mutation happens with a specific person who then is a node (or branch) in the mtDNA tree. Every living person with that mutation in their maternal DNA came from that same woman long ago where it first occurred.
Yes, each mutation denotes a "special mother." In Jemima’s case, there was a woman who lived about 50,000 years ago in the Near East whom the geneticists have labeled "J". She is our (Jemima’s) super grandmother, and her maternal descendants are said to be in her "Haplogroup." (“Haplo” is the greek word for “single” meaning that everyone with that genetic signature is related back to a single person.)
The haplo subgroups can be further refined as more people are tested. For example, a subgroup of "J" known as "J1b" is thought to be part of a group that migrated to the Mediterranean about 6000 years ago. The woman that carried that "J1b" mutation is another one of our "grandmothers." The haplogroup for Jemima is further refined to "J1b1a1." The timing of this last mutation and its location appears to be in Great Britain in the last 1000 years, but that needs to be refined.
Carol Baker’s mtDNA results should be identical to those of Jemima Campbell Tice. The chance of a mutation to the mtDNA over those six generations is a possibility, but small. Other maternal descendants of Jemima should share the exact same mtDNA signature. In fact, this mtDNA signature is likely unique to a “grandmother” up to 22 generations in the past. A match would identify a person with whom Carol and Jemima share a common ancestor.
Unfortunately there are not a lot of mtDNA results with which to compare. Carol has one “match” with genetic distance of “1” meaning that all of the markers are the same except for one. FamilyTreeDNA does not calculate the probabilities of such a match having a common ancestor, but my crude estimate is that there is only a 50% chance of that person sharing a common ancestor with Carol after the year 1600. In this case, the match had no genealogical information on their maternal line prior to 1900, so there was little to be gained anyway. One path of research might be to collaborate with this person on tracing their maternal line to see if it leads back to Newark.
A second “match” had a genetic distance of “2” meaning two of the markers did not match. This decreases the possibility of a very recent common ancestor, but indicates the likelihood of a common ancestor perhaps 15-40 generations in the past. The maiden name of the person in this line that lived in the early 1700s is Elkins, which is a name with English origins.
The maternal ancestry of Jemima's mother is European and highly likely out of Great Britain. As more people with known genealogy are tested, the possibility of “exact matches” with Carol’s mtDNA increases. The data from those matches will yield more information about recent ancestors of Jemima's mother. Carol's test results will undoubtedly help other genealogists as our line of known maternal ancestors extends about ten generations which is relatively long for "known" maternal lines.