Native American Ancestry
In addition, according to the latest US Census, there are apporximately 4.3 million Americans claiming some degree of Native American or Alaska native ancestry. Approximately 3.1 million of these individuals claim membership in one of the over 562 federally recognized tribes. Many Americans seek to verify their Native American ancestry and tribal heritage. To gain membership, a number of tribes set a standard that an individual must have at least one Indian grandparent or one great grandparent, while others require links to members on a tribal membership roster in past generations. Despite the obvious genetic link, in the Indian culture, tribal membership at times can be a question of politics and culture, not biology. One can be considered Native American if one is recognized by a tribe as being a member. Native American ancestry from a genetic perspective does not guarantee tribal membership.
The Genetic Legacy of Genghis Khan
Genghis Khan, at the time of his death in 1227 was the leader of one of the fiercest armies the world has ever seen. He was driven by a lust for power and also driven by lust itself. Genghis brought a new wife home from every campaign and had a harem of at least 500 women. According to writings 100 years after his death there were already more than 20,000 people of his lineage at that time. A recent population genetics study, reported by the American Journal of Human Genetics, examined the Y chromosomes of 2,123 men from regions across Asia. The Y chromosome, found only in men, is passed on unchanged from father to son just like a surname. In this study, over 90% of the subjects had a very diverse Y choromsome profile, indicating multiple paternal ancestors. In sharp ontrast 8% of the subjects had Y choromosmes that were essentially identical, indicating a recent common ancestor. It is estimated that his chromosome occurs in 16,000,000 men, or 0.5% of the world's population. This study, authorized in part by the world renowned geneticist Spencer Wells, concludes that this lineage is likely from male descendents of Genghis Khan and his male relatives.
Genetic Markers
Through DNA analysis of select global populations, scientists have devised two genetic classification systems to define the over six billion people in the world today. One system traces male ancestry through the Y chromosome (paternal lineage) and the other uses mitochondrial DNA to trace maternal lineages. While the genetic landscape has likely changed somewhat in the last 400 years from human migration, genetic analysis can provide some degree of ancestral information lost to history. Each male individual in the world can be placed into one of eighteen genetic classificatins or Y haplogroups, based on their DNA composition. Modern females can be classified into three mitochondrial DNA (mtDNA) haplogroups, Each Y haplogroup is defined by rare DNA mutatuions on the Y chromosome called SNP's or single nucleotide polymorphisms. Any two men sharing a particular SNP in their DNA inherited it from a common male ancestor who lived many thougsands of years ago. Through this classification, scientists have identified select markers in human genes that tend to be found almost exclusively in Native American populations or African American populations, and so on.
The Y Chromosome
The male lineage Y chromosome is extraordinarily useful in tracing male genetic lineates. Found only in males, the Y chromosome is passed from generation to generation relatively unchanged from father to son, similar to surnames. As a consequence of this inheritance mechanism, it becomes extremely powerful for genetic genealogy and ancestry. The power of the Y chromosome has been used to demonstrate that Thomas Jefferson likely fathered a child from his slave, Sally Hemming. There are two types of Y chromosome tests, the Haplogroup Test and the Haplotype Test. The Haplogroup Test helps define individual's ancient origins. In contrast, the Haplotype Test can help locate recent relatives from a single generation up to 25 generations or more, representing a more recent time period.
A haplotype is a set of closely linked genetic markers inherited as a unit. Each person is a mosaic of their mother and father resulting from a blending of the DNA they receive from each. An exception to this is the Y Chromosome which is male specific passing only from father to son. Any sons a man fathers will also carry this identical Y chromosome, including any minor mutations or polymorphisms. Polymorphisms in a man's Y chromosome are also passed directly on to his sons, and then on to their sons and so on. These polymorphisms are the basis for a persons's haplotype and are unique and distinguishing from those of other men. Scientists have determined approximately how often certain kinds of mutations occur and can look for these and determine how closely related any two men are. The more polymorphisms two men share, the more recently they had a common ancestor. The genetic markers in the Y chromosomes of living men contain a historical genetic record of man. Genetic analysis of the Y chromosome can reveal relationships between different groups of men.
Genetic Record
The scattered remains of distant ancestors have been the tools of the trade for paleoanthropologists and archaeologists for ages. While these ancient bones and artifacts reveal shadows of the past, modern science has revealed a complete record of the prehistoric migrations of man inscribed within human DNA. Over time, genetic mutations occur within regions of DNA and are subsequently passed from generation to generation, developing different clusters of mutations in regional populations. By evaluating these clusters relative to global populations, the broad migratory movements of man can be determined and ancestry established.
