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SNP Branching of the Shattocke Family

by Philip Shaddock

Without DNA testing and analysis we would probably never know how the family branched from a single founder born about 1360 AD in west Somerset, England. DNA testing has found very rare mutations of the male Y chromosome of descendants. These mutations are called SNPs: single nucleotide polymorphisms. All male direct descendants of the founder have a mutation called Y16884 that is unique to our family among all the people on this earth. Included in our family branching are the Parrishs and Byars who descend from a Shattocke male who was transported as an indentured servant to the colony of Virginia in 1637. 

You can date the SNPs using a molecular clock with a well known frequency. From DNA tests of thousands upon thousands of male humans we know SNPs mutate every 144.41 years, on average. Like the roll of the dice, the interval between SNP mutations can vary because it is a random event, but over time the interval averages to 144.41 years. The following diagram shows this random appearance of SNP mutations (colored dots) in our family tree.  The empty dotted circles represent a generation without an SNP mutation. 

The single male ancestor of all Shattockes, Parrishs and Byars is at the top of the diagram. On average during the medieval period only one male child survived to produce the next generation. It was also the era of the plague. Shattockes first show up in the written record in west Somerset in 1450 (Thomas Shattocke, tenant farmer in the Taunton area) and 1454 (Roger Shattocke, cloth merchant in the Stogumber area). 

From the founder to Thomas and Roger there have been no intervening SNP mutations discovered so the evidence for our "Cain and Abel" has not been discovered through SNP DNA testing. But there is another form of DNA testing that has provided scientific evidence for the two branch theory of the Shattocke family tree. A type of mutation called an STR (short tandem repeat) is also a rare mutation found on the male Y chromosome. There is a mutant STR called FTY14=9 that only descendants of Thomas Shattocke the tenant farmer have. Descendants of Roger have one more repeat for this STR marker, FTY14=10. This clearly divides the tree into two branches. 

I call the descendants of Thomas the Staplegrove Shattocks after the village where they are found. DNA testing has discovered a branch of the Staplegrove Shattocks called the Bishop's Lydeard Shattocks, after the village where they are found next door to Staplegrove. If you look down the Staplegrove lineage, you will see that I have it splitting into two branches named BY32358 and BY31487. That is because the DNA tests of two descendants (Ken and Simon) of the Staplegrove Shattocks show the presence of BY32358. DNA tests of two Bishop's Lydeard descendants showthe presence of BY31487. We say that these SNPs are "private" to these two Staplegrove branches.  It is the FTY14=9 STR mutation that tells us that the two branches share a common ancestor under Thomas Shattocke. 

Originally I thought that there were six branches of the Shattocke family (including the Parrishs and Byars) but that did not make sense. It is highly unlikely that the founder in 1360 AD would have six surviving sons and even less likely the descendants of six sons would have descendants living today. There is a high attrition rate of branches in subsequent generations, a fact that is made abundantly clear when you consider that a large percentage of western Europeans are descended from a single founder who lived 5,000 years ago.  All his cousins failed to have living descendants. In fact the discovery of the FTY14=9 mutation together with the genealogical evidence makes the two branch scenario almost certain.

In the family tree at the top of this page, the sub-branches of the family (Staplegrove Shattockes, Stogumber Shattocks, Parrishs, Milverton and North Molton Shattockes) seem to suddenly come into existence about 140 years after the birth of the founder. We had a single founder in 1360 AD and the family grew slowly over the next 150 years during the plague, wars and famine.  The FTY14=9 mutation and the genealogical evidence provides evidence for this scenario. It helps to have a very good genealogical paper trail in this case, as the descendants of Thomas Shattocke are very well documented. The date for the origin of the FTY14=9 mutation is not known, but we can be sure that the Staplegrove and Bishop Lydeard's Shattocks are descended from Thomas Shattocke born circa 1420.

SNP testing is limited in its ability to reveal branching of the tree because SNPs have a frequency of about once every 144 years. But STR mutations are much more variable. And different STRs have vastly different mutation rates. The FTY14=9 mutation is so slow it has a mutation rate that is apparently even slower than an SNP. Many STRs are much, much faster. 

A new branch of the family can be discovered by examining the genealogical evidence (especially wills) but the proof of descent from a common ancestor is the DNA evidence. Families adopt children or people change their names. But DNA stores a record that cannot be altered. DNA can discover that two people with no record of a common ancestry and different surnames can have a common ancestor. This occurred with the Parrishs and Byars. If you look at the SNP Frequency chart above, you will see that Parrishs and Byars have an SNP called A8033 (blue dot on the graphic). YFull, the SNP intepretation service, using an algorithm that is based on the molecular clock (144.41 years) have calculated that the SNP came into existence about 1640. This date coincides with the date of arrival of Jon. Shattock (ca. 1616), an indentured servant, in the Virginia colony. If you follow the line of descent to him from the founder Y16884, you will see there was no intervening SNP. On the surface it appears this branch of the family suddenly popped into existence in 1640. But A8033 descendants show they are FTY14=10, so we know they are likely descendants of Roger Shattock. 

There is also considerable genealogical evidence that the A8033 Parrishs are descended from a common ancestor in ca. 1640. The Parrish family tree shows that they also have a two branch structure, defined by the Y19410 SNP. And like the Shattocke family tree, the individual sub-branches appear to spring into existence in the early to mid-18th century. 

The Y19410 SNP is a branch of the A8033 SNP.  At this point you have to ask: "Why so few SNP mutations in the past 380 years?" This is the same question you might ask of the Stogumber Shattocks and their Y19751 SNP.  And the reason why is the same in both cases. Both had a single founder of their branch about 1640: Jon. Shattock in Virginia, and William Shattock (cum Shattuck) in Massachusetts. There was a very rapid expansion of the branch as sons moved to new frontiers, founded their own farms and raised large families. Each of the sons formed a new branch. In fact this is the same scenario as the Shattocke family as a whole. There is a single founder in 1360 AD during a time of low fertility because of the plague, wars and famine. Beginning in the middle of the 15th century there is a huge population explosion that lasted for many generations.

If you look at the descendants of Thomas Shattocke in both the phylogenetic tree and the SNP Frequency chart, you will see he has relatively few surviving descendants. There may have been other SNP mutations among Staplegrove branches, but they have no surviving descendants. The two branches indicated by the red and pink dots were separated sometime before 1750, which probably explains why the Bishop's Lydeard and Staplegrove Shattocks do not share a common SNP all the way back to the founder in 1360. But they do share an SNP that occurred within their sub-branch. So again we see branching seeming to appear suddenly centuries after the founder.

The same scenario is probably true for the Massachusetts Shattuck and Virginia Parrish branches. The only way you can discover a common ancestor in DNA test subjects is when two descendants of that common ancestor share a common SNP or STR mutation.  William Shattuck (1622-1672) descendants share the Y19751 SNP with the London Shattucks, but we would not know of the existence of William except through the careful genealogical records of Lemuel Shattuck. As we test more William descendants we are discovering new Shattuck SNPs from people who have a common ancestor within the past 200 years. And we have discovered STRs that help us organize descendants into sub-branches. The lesson here is to test people who share a common ancestor within the past 200 years.

We have only discovered one SNP, Y19410, among Parrishs and Byars descendants. Why? Like the Massachusetts Shattucks, the founder was born relatively recently in terms of the molecular clock, around 1640, three hundred and eighty years ago. And the family branched heavily during its expansion out of Virginia, with attrition perhaps losing some SNPs. But like the Massachusetts Shattucks a simpler reason emerges. These branches have a lot of sub-branches that came into existence in the 18th century and then scattered. There just has not been enough time. And not enough descendants from the individual branches who have DNA tested for us to find the unseen SNPs.