Surnames

Background

The JAMAICA DNA Project welcomes everyone with direct Jamaican Y-DNA (father line) or mtDNA (maternal line) heritage. The goal of this project is to match up individuals or families who share direct male or direct female Jamaican ancestry and to trace their origins back to Africa, Europe and Asia.

This is a geographical project involving a Y - Chromosome study and a mitochondrial DNA project. Participants must have direct paternal line ancestry in Jamaica or direct maternal line ancestry in Jamaica. The primary goal is to help family historians trace their ancestry and identify genetic cousins.
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For a quick primer on HOW DNA TESTING CAN BE USED AND INTERPRETED check out these excerpts from Chris Pomery’s book: “Family History in the Genes
– trace your DNA and grow your family tree”

Y-chromosome and mitochondrial DNA tests try to link you with a specific group of historical people such as a tribe. These tribal identification tests often use standard Y-chromosome and mitochondrial DNA results and then add a specialist interpretation to link particular DNA signatures as typical of specific tribes or to signal a particular geographical origin.

1. SURNAME BASED DNA PROJECT – YOUR DIRECT PATERNAL LINE (for men only) the most common kind – uses a specific test that targets the Y-chromosome. As this chromosome is found only in men, the transmission of this particular genetic data from father to son from generation to generation exactly mimics the handing down of surnames.
NB of all the DNA tests on offer, THE Y-CHROMOSOME TEST IS THE MOST IMPORTANT ONE FOR THE FAMILY HISTORIAN because its primary use is to help recreate and to check the accuracy of your family tree even though it can only help with one specific line in that tree, the direct paternal line.

Almost all testing companies nowadays offer a male-line test that is a combination of the standard Y-chromosome DNA test together with an identification of that DNA signature’s haplogroup. The haplogroup (SNP markers) test is another name for a DNA test that looks at the one-of-a-kind mutations that migration scientists have used to divide humanity into large groups. Imagine the haplogroup result as defining the ‘suit’ in a pack of cards and the DNA signature as defining the ‘value’ of individual cards.

SOLVING A PROBLEM IN YOUR FAMILY TREE…

The most simple of the problem-solving scenarios is to show that the descendants of two or more men bearing the same surname share a common ancestor.
A Y-CHROMOSOME TEST RESULT DEMONSTRATING THAT BOTH MEN POSSESS THE SAME DNA SIGNATURE PROVIDES THE BEST PROOF OF COMMON ANCESTRY – SHORT OF FINDING THE MISSING DOCUMENTATION – THAT ONE COULD ASK FOR.

Here’s a summary of some scenarios that a Y-chromosome test might help to solve:

• To prove, or disprove, a connection with a known historical person e.g. a clan chieftain, a first immigrant or a famous fellow name-bearer.

• To establish whether two (presently unlinked) family trees are related through a common genetic ancestor within a timeframe that accounts for their shared surname.

• To test a number of people with the same unusual surname in countries of emigration and immigration in order to match together a family in the New World with it’s ancestral family in Europe or Africa.

• To unravel or verify several family trees that may have become jumbled up because several male ancestors had the same forenames and lived in the same geographical area at the same time.

At its simplest level, a Y-DNA (male line / surname) project consists of aggregating DNA signature results from as many men as possible with the same surname and analyzing the patterns of connection – by building up genetic families – that emerge. This process usually produces immediately useful results because THE GENETIC FAMILIES REVEAL PREVIOUSLY UNSUSPECTED LINKS BETWEEN MEMBERS OF DIFFERENT FAMILY TREES AND SUGGEST FURTHER LINES OF DOCUMENTARY RESEARCH.


MRCA – Most Recent Common Ancestor
A calculation is available to researchers to determine the date when two men shared their Most Recent Common Ancestor. This estimates the number of generations back in time that two men shared their common ancestor. It does this by looking at the differences between the two DNA signatures and working out how long ago those two strings of results could have been identical (i.e. what length of time would have needed to elapse for the two strings, once identical, to have accumulated the mutations needed so that they look as different as they do today). It is important to understand that the MRCA calculation can only ever provide a very approximate answer to the often vital question – when did the common ancestor live?

2. FEMALE LINE – THE MITOCHONDRIAL DNA TEST TRACKS THE FEMALE LINE OF INHERITANCE by measuring genetic data passed down from the mother.

One of the disadvantages of mtDNA results arises from THE FACT THAT THE AVERAGE RATE OF MUTATION OF MITOCHONDRIAL DNA IS VERY MUCH SLOWER THAN THAT OF THE Y-CHROMOSOME. This means not only that pinpointing _when_ a particular mutation occurred is very difficult, but also that it almost certainly happened a long time ago. One upshot of this is that if you compare your mitochondrial DNA result with everyone else who has ever taken the test you are pretty much guaranteed to find others with exactly the same result as yours. However, YOU ARE LESS LIKELY TO BE ABLE TO IDENTIFY WHETHER THE DIRECT MATERNAL ANCESTOR YOU SHARE LIVED RELATIVELY RECENTLY OR EVEN TENS OF THOUSANDS OF YEARS AGO.

Another limiting feature of mtDNA, from the point of view of family historians, is that it is only passed on from one generation to the next by a mother through her daughter. A son inherits it, but does not pass it on to his children.

“WHEN IS A TEST USEFUL?”

The genealogical value of your DNA test result is only created when you compare it with the results of other people’s tests.

Your result will, of course be different to most people’s, similar to many people’s but the same as only very few people’s. It’s up to you to decide who among this pool of potential matches is relevant to your family history research.

“DNA testing is only for advanced genealogists with years of research behind them”

The real utility of a DNA test is that it can save you years of fruitless endeavour by directing you in the right direction at a very early stage. A DNA test can provide you with the names and email addresses of other researchers with whom you can be confident you share a recent ancestor. In many cases, one of these will have already done a great deal of the relevant historical research, leaving you with the much easier task of connecting to an already established tree.

It often happens that the trees grouped together by the DNA results into a genetic family seem to originate in places that are very far apart and where there is no obvious historical connection. It’s these cases that show the immense value that DNA testing can bring to our generation of genealogists: evidence of linkages like this are unlikely to come from any other source.

As the number of test results available for comparison in the online databases increases month by month, so the kind of inferences once can draw from those comparisons deepens and the confidence one can place in them improves.

We may want DNA testing to play a role in solving the documentary gaps and problems in other parts of our family trees, but there are sound reasons why this is going to be difficult to achieve. Targeting the direct paternal line and the direct maternal line is a start, but ten generations back my tree should contain as many as 1,024 individual direct ancestors.

Y-DNA TEST --- INTERPRETING YOUR TEST RESULTS

NB It’s only with tests of 37+ markers that the various genetic families will differentiate themselves clearly enough that the results can be used with condience to direct your documentary research.

Sample 10-marker Y-chromosome result (NB this is an extremely low resolution test, just using it to explain how to interpret test results)
Marker name
19 388 390 391 392 393 389i 389ii 425 426
Your result
14 12 24 10 13 13 13 29 12 12

The table shows the names of specific places on the Y-chromosome (the marker names) where the lab has tested the chemical composition of your DNA. The result they found is expressed as a numerical value. Your overall Y-chromosome test result is, in effect, a string of numbers. You can think of this string of numbers as your personal Y-chromosome DNA signature.

The fundamental principle underlying all DNA tests is that our DNA is handed down from one generation to the next according to fixed rules.

When it comes to the Y-chromosome, the process of genetic copying allows for only minute variations between the DNA of a father and the copy of that DNA given to his son. When analyzing Y-chromosome results we therefore make the assumption that the DNA signature of a man taking the test is identical to that of his father, his father’s father and so on, back through the generations along that direct paternal line.

Occasionally, though, some small changes do occur from one generation to the next: these are known as genetic mutations and they are the feature of DNA that allows us to see meaningful differences between individual DNA signatures.

A genetic mutation is simply a glitch in the process of copying the DNA from parent to child. Scientists have a rough idea of how often mutations occur from generation to generation, and the current thinking is that, over the 700-year timeframe which is the focus of a genealogical research, mutations are quite rare. Within the context of a surname analysis, when comparing a set of results of men with the same surname, we can say that those with the same or very similary Y-test result are likely to be related (and thus to be members of the same family tree).

ABOUT MUTATIONS
The Y-chromosome is passed down intact from father to son.

The differences between individuals are accounted for by mutations. The DNA measured at all the different markers mutate at different rates.

When scientists were trying to unravel the migration history of humankind they were looking for DNA markers with a special characteristic: those that had mutated only once, in one human at one time and in one place, creating a new marker value that would then be held by every single one of that person’s descendants and by no others. By sampling present-day populations around the world for these one-time-only mutations it became possible to see where that mutating individual’s descendants had moved to. By working backwards, the scientists could estimate the time when each mutation had occurred and the rough geographical area where that individual had lived when the mutation occurred. Today with several hundred of these one-time-only markers being used, the migration map of humankind is coming into ever clearer focus.

Example
Let’s use the results in the table below to show how these principles work in practice. We’ll start by comparing several Y-chromosome results with each other.

Sample 10-marker Y-chromosome result
Marker name
19 388 390 391 392 393 389i 389ii 425 426
John SMITH
14 12 24 10 13 13 13 29 12 12
Doug SMITH
14 12 24 10 13 13 13 29 12 12
Fred SMITH
14 12 24 10 13 13 13 29 12 12
Alf Turner
14 12 24 10 13 13 13 29 12 12
Bill SMITH
14 12 25 11 14 15 11 28 12 12
Geoff TURNER
14 12 25 11 14 15 11 28 12 12

Firstly, we can see that John Smith and Doug Smith have identical results: the numerical values are the same on all markers. Fred Smith’s result is almost the same, except that on marker #388 he has the value 11 while John and Doug have 12. Bill Smith’s result, however, is markedly different. His values are different from John Smith’s on six of the ten markers. Turning to look at the two Turner results we can see that Alf Turner’s result is the same as those of John and Doug Smith while Geoff Turner’s result is the same as Bill Smith’s and different from that of his namesake Alf.

The process of interpreting these results is straightforward. John, Doug and Fred look to be related to each other because their DNA signatures are identical, or almost identical, and they share the same surname. Alf Turner’s result is the same as that of both John and Doug Smith, but the fact that he has a different surname would lead us to suspect that common paternal ancestor he shares with them pre-dates the period when surnames were adopted (about 500 years ago).

Bill Smith is not genetically related to the other three Smiths as his DNA signature is very different, so his Smith line most likely had a different paternal ancestor who adopted the Smith surname at another time and in another place. If, however, we know that Bill has been documented as a member of the same family tree as John, Doug and Fred, then we need to explain why his DNA signature is different from theirs. If that is so then clearly somewhere along the line of his direct paternal ancestry some else’s Y-chromosome DNA has been substituted for the DNA signature held by the shared ancestor of Bill, John, Doug and Fred.

MITOCHONDRIAL DNA TEST

Compared to the Y-chromosome test, the genealogical uses of the mtDNA test are limited and highly specific. But if it is technically possible to use the mtDNA test to confirm your particular hypothesis then it can be an extremely powerful tool.
As the test can only be used in relation to the direct maternal line, the two people being tested have to believe that they share a common direct maternal ancestor.
One application might be to prove, by testing their direct maternal line descendants, that two women were sisters (or maternal cousins). Another case might involve testing the descendants of the daughters of two brothers in cases where you are not sure which daughter was born of which mother, if you can find a direct female line descendant from the disputed daughters, plus a direct female line descendant from each of the two wives (whose mitochondrial DNA results will be different to each other’s), you will be able to identify the correct mother. Another case might be the situation of a man with multiple wives where the birth date (and therefore identity of the mother) of a female child is unclear; again one would need to test a direct female descendant of each of the potential wives as well as of the child to reveal the true mother.
Just looking at these mitochondrial DNA test scenarios reveals that they are generally more complex than the typical Y-chromosome scenario. They also tend to relate to more modern genetic links, back just a few generations, as it is so much harder to research maternal lines further back.
One area where a mitochondrial DNA test can deliver strong benefits is in cases where there is no option to document family links within the standard genealogical timeframe, for example where the documents simply never existed. The deep ancestry link that the results can reveal is of much greater value to a researcher if he or she cannot find new information about their origins in other ways.
One example is someone who believes their maternal lineage traces back to a slave forcibly brought from Africa to the USA. In such a case, the paper trail might run out one or more generations after that female ancestor was brought to the Americas, leaving their origins in Africa completely obscure. Nowadays a mtDNA test result can be matched against a global database that includes results taken throughout modern day Africa, which can pinpoint a region or country in Africa where the same mtDNa result is found today. As migration patterns in Africa are broadly known in the period of the last 500 years, the ancestral motherland associated with that particular mtDNA result can be identified. In effect, the mtDNa tst has found that descendant’s maternal homeland.

THREE TIMEFRAMES:
The knowledge DNA results can supply falls into three historical timeframes, each offering different insights into your genetic and historical origins. You need to bear this in mind when you decide which DNA test is the right one for you.
• The first and most important timeframe lies in the modern era, from the presnt day back to the end of the medieval period around 1500 AD. This 500 year span is the era of documented records when surnames in England were passed down regularly from father to child. Within this timeframe you can reconstitute a forgotten family tree through diligent research on the web and in the archives, using DNA testing as a tool to guide and verify your research.

• The second time frame lies a bit further back in history, in the period before surnames were well established, back to the time of the great classical writers who recorded at first hand what for us are the key events of ancient history. This fifteen century long period runs from the middle of the last millennium back as far as the Roman occupation of Britain. Within this timeframe, your DNA test results might indicate whether your ancestors were participants in a well known historical transition. For example, they might suggest a connection with the expansion of the Vikings from Scandinavia along the western Atlantic seaboard, or the westwards spread of the followers of Genghis Khan across Europe from their homelands in the Mongolian steps.

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