What Ancestry.com calls AncestryDNA is autosomal DNA. It can tell if two people are likely related (it isn't foolproof) by comparing long strands of identical DNA. It can't tell HOW people are related, only that they likely shared a common ancestor at some point (this knowledge is mostly only helpful with an accurate paper trail that proves your lineage to a shared ancestor). Ancestry.com can also estimate the number of generations back when this DNA was shared, though the accuracy declines the farther back that the match occurs.
It was an autosomal DNA match to Jack Callahan (a descendant of Aaron Davis) that enabled me to discover that James Davis was my 4th great grandfather, and that discovery led to the current book project. And that in turn has led to the realization that a lot more Davises from Jackson County, Illinois are related to one another than had previously been the case.
Another Davis match of mine is Patricia O'Leary, though we don't know which Davis brother from whom she descends, except that it was not Aaron. Because of this, her line has not yet been included in the book, but I intend to add it to the next draft, along with analysis and/or speculation as to how her ancestors connect to one of the three Davis brothers. I had originally thought it most likely that she descends from one of James' sons, but my current analysis suggests that is far from certain. I hope to post about that soon.
So I know that I have AncestryDNA matches with descendants of at least two of the three brothers. But there are also other distant Davis cousins for whom I do not share common long strands of DNA. That is understandable, as in each generation only half of the DNA is inherited from each parent. So the farther removed from the common ancestor, the less likely that descendants will share significant amounts of Davis DNA. It is also possible for a Davis Cousin A to have more than one strand of Davis DNA. So Cousin A could match with both Cousin B and Cousin C, but Cousins B and C might not share a match. That is how Ancestry.com's DNA Circles work. If we can get enough Davis descendants tested, in theory a DNA Circle would be created showing which cousins we match directly to, and which are inferred by those cousins with matches on more than one DNA strand. The more connections, the greater the confidence of our shared relatedness.
It would be very helpful to be able to identify any researchers who descend from either James, Aaron or Amos Davis who have taken an AncestryDNA test, or at least to identify those who are willing to share that information. My hope is that we could use this knowledge to visit each other's Ancestry profiles, where it would tell us whether we share matching DNA (for distant cousin matches, this is much easier than slogging through thousands of potential 5th cousin matches). Hopefully that would show inter-relatedness among all three Davis lines - James, Aaron and Willis, and thus validate the research behind the book.
Having your siblings and close cousins perform AncestryDNA tests can also be very helpful, as those close relationships can narrow down which common DNA strands are inherited from your father or mother (and thus which is likely to have Davis DNA, as opposed to your other family lines). Having your oldest living Davis ancestor tested would be even more helpful, as it would further isolate which common strands are Davis strands.
If there is sufficient interest in doing this, I would keep track of the results on a dedicated page on the blog, and would provide a link to them on the blog. If there is enough information compiled to be meaningful, it would be included in the book, likely in a summary of some sort.
One last thing. I added a Contact Form link to the blog. If anyone reads any posts and has comments or questions, this form allows them to contact me directly without having to do so through their mail program.
