Project Goals
The Y chromosome (yDNA) provides a powerful tool for discovering ancestral male lineages because, unlike other chromosomes, its DNA does not change much as it is passed down from father to son.
Occasionally, however, when a Y chromosome is passed on, its genetic code undergoes a very small alteration (mutation). Most are completely harmless and so are eventually passed on to succeeding generations. Over time, additional alterations occur. In this way, separate male lineages become different from one another.
Only males inherit a Y chromosome. Surname analysis, therefore, can only be performed on male DNA. However, women can get information by using a sample from a male relative.
By comparing men’s Y chromosomes, it is possible to judge how closely they are related. If their genetic codes are very similar, we can say that they share a common male ancestor in the recent past. The more differences in their genetic codes, the more generations have passed since their last common ancestor.
Scientists have used this principle to compare the DNA from thousands of men around the world. As early groups of humans spread out from our point of origin, family lines gradually began to diverge. It is these different lineages that form the separate branches of the global family tree and can sometimes tell us where we belong on it.
By comparing female (mtDNA), it is possible to judge how closely they are related. If their genetic codes are very similar, we can say that they share a common female ancestor in the recent past. The more differences that have accumulated in their genetic codes, the more generations have passed since their last common ancestor. But of course, that is biological and of little use in Surname research because women have tended to change their surnames at marriage (sometimes more than once as they re-married).