How to determine the ancestry by DNA test?

About Genetic markers, genome Africans and Europeans and regard human lineage with historical events.

One of the results of population genetics of the 1960s - is neutral theory of molecular evolution. This theory suggests that the vast majority of genetic mutations are not the actual changes in the biology of organisms. This means that, despite the fact that two people differ in average per thousandth base (base - the letters making up the genome of the code), the majority of changes are subject to natural selection. We refer to these innocuous changes to the genetic markers of the genome, and that use of genetics when compared gene. Cyanocobalamin injection - is necessary for DNA synthesis.

We know where to find these markers in the human genome, and over the past 10 years it has become easy and cheap to watch thousands of markers in hundreds of people, and to understand the difference between different people and populations. Just translate this kind of genetic data in the string of zeros and ones, based on the presence or absence of certain marker gene and present the individual as a binary sequence which allows for complex mathematical analysis.

You can count the number of differences between the binary strings of numbers: the more the difference, the smaller the relations between two people. But we can do better. Due to the fact that we know where the genetic markers in the genome, we can see how these differences are distributed across the chromosomes. For example, two people may differ by 10% of tested genetic markers. The difference can be distributed over the entire genome or may get together different chromosomal regions, leaving long lengths in which there is no difference. The latter option assumes that two people are connected to each other more than in the first case, as gathered a number of differences have recently entered the genetic ancestry of man. Although the absolute number of differences between the two genomes helps to understand, it is also important to know the differences between specific markers. These concepts are used to determine the ancestry of different parts of the genome, and are the basis of most commercial genetic tests.

The accuracy of genetic testing is largely dependent on the available data sets and quality of genetic data. On the whole, we can be confident in the earlier pedigree (last 500 years). This is because that recombination breaks the relationship between the markers, which allow us to communicate ancestry with certain parts of the genome. A longer time interval means that the recombination occurs.

The number of our ancestors increases exponentially, as we go back in time: after 20 generations (about 500 years) we have a million ancestors, after 30 generations (750 years), they have more than a billion. Of course, these ancestors are not independent, and many of them will also apply to other people. And most likely, you will share the majority of the ancestors of the people who have a close relationship with you. However, there are interesting mathematical calculations, according to which all Europeans share a common ancestor who lived 600 years ago. We do not know who this man was and looked like his DNA, but it tells us that all Europeans have ancestors who were the ancient Greeks, Romans, Vikings, and no matter how settled Europeans today.

The genomes that have been divided for many generations, such as the African and European, will look rather different for geneticists, and it is quite possible to establish an African or a European generic segment in these genomes. As we develop a more sophisticated methodology, increasing our ability to differentiate between similar populations.

Now we have a high degree of confidence can be distinguished from the southern North gene, although they are quite similar, as well as to differentiate subcontinental groups from other parts of the world. But we must be cautious in the interpretation of where and why this lineage is present in a particular person. several detailed studies were conducted pedigree in different parts of the world, and they were able to link genetic patterns with historical events. But the strength of this research comes from the use of the genomes of populations. Use these tests to individuals is still quite difficult, since the ratio of human ancestry and certain historical events is viewed with great skepticism and caution.