The Genetic Sequences Implicating West African Origin - Research Paper Example

Ancestral origin is sought to try to complete one’s identity. In addition, some people would like to know their ancestral lineage, since the association to a group that big adds a sense of belonging to humans inherently seeking social relevance. Somehow, the ancestral lineage, no matter what it consists of, becomes part of the family, and a group that huge has certainly made relevant contributions in history, no matter how old or recent those contributions were. Current scientific advancements (further discussed below) allows an individual to determine whether they came from the lineage of Bible figures Moses and Aaron, or of Genghis Khan, US President Jefferson, and other historical figures (www.rootsforreal.com). Before the advent of molecular technology, ancestral lineage is based on the recollection of and stories passed by the oldest living family member to the younger family members. People born from the same continent also have some attachment, as it seems logical to think they could have come from the same ancestors because of the proximity of their parents with one another. Now, DNA analysis becomes a way of objectively verifying those theories. By comparing the nucleotide sequences of samples against a sequence database from more than 75, 000 indigenous and traditional populations from all over the world, (Biological and Environmental Research Information System, 2010), DNA sequence unique to people from a certain continent, country, town, village or family may be identified (Rotimi, 2003). These populations are each composed of people living within a particular region for several generations and maintaining the same culture (Biological and Environmental Research Information System, 2010). Anyone who would like to determine his or her group of origin can thus look for these unique sequences in his or her own genome. An example of a population seeking to define their ancestral origin and the populations that have the same ancestors is African-Americans. Certainly, the parallelism in their experiences with slavery and obvious similarities in appearance motivate the effort of linking African-Americans with modern-day Africans. The results of many DNA studies suggest that the common female (140, 000 years old) and male (60, 000 years old) ancestors of modern humans are from Africa. Migration started 65, 000 years ago, when they populated southern Asia, China, Java and Europe (Biological and Environmental Research Information System, 2010). Such movement has caused a modern human population, such as African-American, to be genetically-diverse. For example, African-Americans can have a European Y-chromosome because of the historical admixture of African farming employees to European plantation owners (www.rootsforreal.com). As well, in a study of scientists from the University of Pennsylvania and Cornell University analyzing the genetic make-up of 365 African-Americans, 203 people from 12 West African populations, and 400 Europeans from 42 countries, it was found that African-Americans had as little as 1% and as much as 99% West African ancestry. The genetic sequences implicating West African origin was also found to be similar to those of Igbo and Yoruba from Nigeria and Bantu-speaking populations in Western Africa. In addition, their median proportion of European ancestry is 18.5%. Specifically, mitochondrial DNA (mtDNA) origin (mothers) were mostly African, while the Y chromosome (fathers) were African or European (http://www.physorg.com/news180632039.html, 2010). Which tools can be used to determine such ancestral connections? Let us start with the most superficial. If an individual would like to verify connections between him or her and an alleged relative, he or she can request for a DNA fingerprinting test. Using certain sequences at 16 chromosomes, the possibility of a blood relationship is calculated (www.rootsforreal.com). As mentioned earlier, matching mtDNA and/or Y-chromosome with the database of samples from different populations can be done to determine ancestral roots. These genetic materials can be obtained from the saliva of an individual. Of course, only males can determine their maternal and paternal ancestry through their DNA, because they contain both the mitochondria (containing the mtDNA transferred from his mother) and Y-chromosome, while females do not have the Y-chromosome. For the paternal ancestry of a woman, she can instead determine her paternal ancestry by sampling her father or brothers (www.rootsforreal.com). Matching is possible because these genetic materials are passed down the gender lines without the rearranging processes (such as chiasma, or the exchange of material by two homologous chromosomes) other chromosomes usually undergo (Biological and Environmental Research Information System, 2010). Despite the relative unaltered state mtDNA and Y-chromosome seem to have, they are still, like other genetic material, subject to mutations. As such, a specific subset of ancestral lineage bear with them mtDNA and/or Y-chromosome mutations that make certain individuals closely related to each other than to other people containing the same mtDNA and/or Y-chromosome but not the mutation. For example, around 70% English men, 95% Spanish men, and 95% Irish men have the same Y-chromosome mutation referred to as M173 (Biological and Environmental Research Information System, 2010). However, mtDNA and Y-chromosome can only be passed from mother-to-daughter/son and father-to-son, respectively. Thus, they cannot be used in determining the ancestry of grandparents. In such cases, autosomal chromosomes can be used through admixture test. A drawback of this procedure is that since these genetic materials are a random mixture of equal contributions from each parent, it only provides a broad idea of one’s heritage instead of a specific ancestral lineage (Biological and Environmental Research Information System, 2010). Going back to the African-Americans, how then were they able to migrate from Africa? There are different views on how different populations came to be what we know now from a single human population in Africa. The earliest group of mtDNA sequences, designated as L1 and L0, are currently found in the KhoiSan of Southern Africa and the West Pygmies of Central Africa. Through the mutation of the mtDNA of originating population, M and N haplogroups soon aroused. These haplogroups were the ones inhabiting Asia, Australia and some parts of Europe during the Ice Age. Although mtDNA in Australians remains to be M or N, the population in Europe gave rise to haplogroups H, I, J, K, T, U, V, W, and X. Similarly, haplogroups in Asian mtDNA are A, B, C, D, E, F, G, M, and Y. Those in Americas have A, B, C and X, and Papua New Guinea are characterized by P and Q haplogroups (http://www.rootsforreal.com/migrations_en.php). On the other hand, a 2009 publication from University of Pennsylvania found that from the South Africa-Namibian border where the ancestral humans lived, ancient African population migrated northeast, passing through the Red Sea. From here, some inhabited the West Africa. The Niger-Kordofanian language groups then gave rise to 71% of the four populations of African-Americans. Despite such a breakthrough finding in linking African-Americans with their African ancestors, the researchers admitted African and African-American genes are the most diverse (Fink, 2009). Such may determine why there are still around 30% African-Americans with uncertain ancestral background. Despite the amount of information that the current tools on determining ancestral origins give, the results of these processes are still subject to criticism. First, non-believers say the databases available for either mtDNA, Y-chromosome, and gene sequences used for the admixture test are still not wide enough to include DNA material from your ancestors. Also, it is believed that all 46 chromosomes that each of the individuals have should be analyzed by the tests. It is thus possible that addition of new material to the databases as well as assessment of the inheritance of other nucleotide sequences will change the supposed certain ancestral lineage. Surely, such occurrence will cause confusion and tarnished hopes to those that have used the information from the current DNA tests to determine their identity. Other potential problems include questionable membership to affluent tribes just to receive financial gains, and patients seeking for doctors to consider their genetic make-up when making medical decisions (http://www.sciencedaily.com/releases/2007/10/071018145955.htm, 2007). References Biological and Environmental Research Information System. (2010, February 11). Genetic Anthropology, Ancestry, and Ancient Human Migration. Retrieved from: http://www.ornl.gov/sci/techresources/Human_Genome/elsi/humanmigration.shtml Fink, L. (2009, May 1). Out of Africa: Massive Study of African Genetics Reveals Migration and Ancestry. Retrieved from: http://www.usnews.com/science/articles/2009/05/01/out-of-africa-massive-study-of-african-genetics-reveals-migration-and-ancestry Rotimi, N. C. (2003). Genetic Ancestry Tracing and the African Identity: A Double-Edged Sword? Developing World Bioethics, 3, 152-158. (2009, December 21). Genetic Study Clarifies African and African-American Ancestry. Retrieved from: http://www.physorg.com/news180632039.html (2007, October 18) Genetic Ancestral Testing Cannot Deliver on its Promise, Study Warns. Retrieved from: http://www.sciencedaily.com/releases/2007/10/071018145955.htm Ancient Migration. Retrieved from: http://www.rootsforreal.com/migrations_en.php Services. Retrieved from: http://www.rootsforreal.com/service_en.php . Read More