Although the Davenport Surname DNA Project is geared toward following the Y-DNA down the various Davenport lines, that doesn't mean that it is the only choice available. Below is a brief description of the types of DNA that can be used for genealogy. Each has it's own use, so care should be taken before ordering any such test.
The primary test used in the Davenport Surname Project is the Y-DNA test. We test a small portion of the DNA on the Y chromosome, which only males have. This Y-DNA is passed down from father to son, generation after generation, virtually unchanged. So the Y-DNA of a Davenport male today should be nearly identical to his male ancestor many generations ago. Thus, by comparing two individuals, we can determine if they have a common ancestor. It works very well.
Over the years we have tested well documented male descendants of the various Davenport lines, and have been able to establish a base signature or “Haplotype” for each. The Haplotype for a Rev. John Davenport descendent is very different than a Humphrey of Barbados descendent. They are both different from the Newberry Davenport’s, and so on. The Y-DNA of most male Davenports will match one of the dozen or so major Davenport lines.
There are two types of Y-DNA that can be tested. Short Tandem Repeats or abbreviated to STR, and Single Nucleotide Polymorphism (SNP), pronounced snip, The standard Y-DNA tests we use involves STR testing. We can test on 25, 37, 67, or 111 “markers”. The values for the markers are compared between two males and usually the more that match, the closer they are related.
SNP testing is used to determine Haplogroups – a much broader method of categorizing Y-DNA. The results of a SRT test will usually report a pretty accurate estimate of what the Haplogroup is too, and with that information possibly zoom in on a particular world region where the line may have originated. But the Haplogroup estimate is just that - based on others who have had deeper SNP testing and have STR results that are similar to yours - this is what we think your Haplogroup is. In most cases, it is possible to refine the SNP test to a much more specific sub-Haplogroup. Think of it like a tree, with you being very small and climbing to a particular leaf - take the third branch up > seventh branch on the left > second branchlet on the right > fourth twig on the right > third twig on the right > first leaf on the left. You have to follow a specific path of SNP's to get to your leaf or terminal SNP (sub-Haplogroup). There are exceptions, but the original Haplogroup estimate is the equivalent to the first branch. So taking a Haplogroup Deep Clade may be interesting and will allow you to zoom down to a much more recent SNP, but it is still not that useful in genealogy - yet.
Now, with recent advances in technology, there has been a phenomenal increase in the discovery of new SNP"s. FTDNA has a Big-Y test that looks at over 35,000 SNP's. It will soon be possible to distinguish families by their unique SNP's - veins in the leaf.
Important - Before ordering a SNP Deep Clade or Big-Y test, contact the project administrator. If someone in the same line has already tested, another may not be necessary. It is likely the results will be identical.
Mitochondrial DNA (mtDNA) is another form of DNA that is commonly tested. Everyone has mtDNA, but only females can pass it on to their children. So, the mtDNA in each person is from their mother and it is passed down virtually unchanged. Therefore, an individual's mtDNA would be the same as their mother, her mother's mother, and so on, generation after generation. Like Y-DNA, which follows a straight male line, the mtDNA follows a straight female line.
It is unlikely anyone will find a missing ancestor or prove a connection via mtDNA. Due to the slower mutation rate, an exact match would only mean there was a common ancestor possibly within the last few thousand years. It is also much more difficult to track a straight female line. Women tend to take their husband's surname at marriage, therefore there is a name change each generation. However, the test is useful for disproving an ancestor. If two individuals had different mtDNA - they did not have a recent common female ancestor. It is also an indicator of where ancient ancestors may have resided. Haplogroups A, B, C, D, and X are common for Native American, H is very common in Western Europe, etc...
Our testing company, FTDNA, offers two levels of mtDNA testing. The mtDNA+ test captures information from selected bases on the mtDNA molecule. This is essentially just enough to determine the Haplogroup and can disprove a connection. The mtFull Sequence test looks at all 16,569 locations in the mtDNA. This additional information can help zoom in a little deeper into the Haplogroup and possibly more recent deep ancestry. Again, it is probably not going to help in making connections, but exact matches increases the probability.
Some of our male Y-DNA project participants also took the mtDNA test. We have also had many females test too. It doesn't relate to the Davenport surname, but as a courtesy, they are listed here: mtDNA Results
The third type of testing looks at the “autosomal” DNA. Unlike the Y-DNA or mtDNA, the autosomal test looks at the DNA you get from both of your parents. FTDNA calls it their Family Finder test. It cannot be used to compare to Y-DNA or mtDNA. However, it can be very useful when looking for connections on both sides of the family. You get about half of the aDNA from your mother and about half from your father. Since they each get half from each of their parents, that means you receive about 1/4 from each of your grandparents - or 1/8 from each g-grandparents - or 1/16 from each gg-grandparent. As you can see, the aDNA from one individual becomes more "diluted" for each generation. Realistically, it can be used back to about five generations, but it can still be very helpful in the more recent genealogy on all sides of the family.
It is important to remember that Y-DNA, mtDNA, and autosomal DNA are all different and are not interchangeable. A Y-DNA Haplogroup H is not the same as a mtDNA Haplogroup H.