Uncovering the DNA Story

As you stare at your reflection in the mirror, what do you see? Who do you see? It may be a simple question, but there are still some people who would take a while before they answer.subsec-testimonials-hero-lezlie

Take Lezlie for example. She is one of those people who had always encountered curiosity about her ethnicity from people she’d meet. “I probably got the question 3 to 4 times a week if I was Asian or Moroccan or something else,” she says. She is, just like you and me, an ordinary person with ordinary an life but then, upon having the opportunity to find out, she took it and went through Ancestry DNA to find her roots.

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Another person which we may be more familiar however is Trya Banks. The superomodel/ TV mogul confessed that she isn’t the only one who’s been wondering about where her exotic looks came from. “People have been asking me my entire life what’s my family history,” she said on the show, America’s Next Top Model.  “I don’t know; I’m a proud black woman who was born in America. I’m proud of that, but I’m super curious as to what else is running through my veins” says Banks. She uncovered her unique DNA story and found out that she was 79% African, 14% British and 6% Native American which according to the website of AncestryDNA that performed her test is actually quite rare. To have such a high percentage of Native American blood confirmed something that we already knew about Tyra Banks: she’s one of a rare breed. It says that only 1 percent of test takers have more than 5 percent in their DNA (and Tyra had 6%).

Did you know that it is now possible for people to research their own origins, investigate the gene pool of a specific region and even discover to which ancient tribes they belong? Yes. And it is through a technology called the Y-chromosomal analysis. The idea behind this test was described by Dipl.-Jur. Roman C. Scholz , one of the leading experts in the field of DNA genealogy and Dipl. Biol. Joëlle Apter , a geneticist and anthropologist in an article explaining how the 23rd chromosome, which defines the gender of the person, one from the mother(xy) and the father (xy) pass on the clue for the lineage. Females have two X-chromosomes, males have one X and one Y-Chromosome. Mothers always pass on one X-Chromosome. If the father transfers his X, a girl is born; a boy is born if the father transfers his Y. For this reason all sons of one man have the same Y-Chromosome. The sons of these sons have the same Y-Chromosome as their paternal grandfather and so on.test_vaeterliche_linie

Through the Y-chromosomal method, a study was able to single out a Y-chromosome of a single individual which has spread rapidly and is now found in ∼8% of the males throughout a large part of Asia. Assuming that they were able to acquire a sample which is a representative of the population, this chromosome will be present in about 16 million men. Their research suggested that from the available evidence the researchers were able to gather, the paternal lineage was carried by Genghis Khan.

download-1Genghis Khan was a Mongol named Temujin (Temüjin) and took the title Universal Ruler (which Genghis Khan translates to) upon being the greatest conqueror of all time.  In terms of square miles conquered, Genghis Khan’s empire was four times larger than the empire of Alexander the Great. He was a good manager, collecting around him people of talent and eventually, Mongols believed that he had been the greatest man of all time and sent from heaven. He was known as the Holy Warrior, and not unlike the Jews, who continued to see hope in a conquering king (messiah) like David, Mongols were to continue to believe that one day Genghis Khan would rise again and lead his people to new victories. His works earned him the largest land empire in history, however it came with great sacrifice as he is known to often slaughter the conquered populations.

Genghis Khan established his great empire and the fact that 0.5% of the world’s total population suggests that it is possible for the y-chromosome spread results not from a biological advantage, but from human activities recorded in history.

The patterns of variation found in human DNA are usually considered to result from a balance between neutral processes and natural selection which have opposing mechanisms. The mutation, recombination, and migration bought upon by the neutral process is rarely observed in humans. These neutral processes increases the drift in genetics and are observed in cases such as those associated with resistance to malaria or unidentified pathogens that can recognized by the “signature” they leave in the genome. While natural selection process decreases the genetic drift.

In the case of Y-chromosomes assumed to be related to Genghis Khan, 2,123 men with > 32 markers was type to produce a Y haplotype for each man; these included 1,126 individuals described elsewhere. A Y haplotype or the haploid genotype is a group of genes in an organism that are inherited together from the father. Over 90% of the haplotypes showed the usual pattern wherein most males had a unique code; and the few haplotypes present in more than one individual were generally found within the same population. However, in the study by Tatiana Zerjal and associates, they saw one pattern that was novel in two respects. According to their journal the first noticeable aspect was: there was a high frequency of a cluster of closely related lineages, collectively called the “star cluster”. The second was, the star-cluster chromosomes were found in 16 populations throughout a large geographical area extending from Central Asia to the Pacific; thus, they do not result from an event specific to any single population.

snipAccording to them, they were able to deduce the most likely time to the most recent common ancestor (TMRCA) and place of origin of this unusual lineage from the observed genetic variation through: first distinguishing the star-cluster chromosomes from the remainder. For this, they used the criterion that haplotypes linked to the central one in the shaded area of the network without gaps would be included. Then they calculated the TMRCA for the star-cluster chromosomes with two methods. The first method was using the program BATWING by Wilson and Balding in 1998 which uses models of both mutation and population processes. With this program, they estimated ∼1,000 years for the TMRCA (95% confidence interval limits ∼700–1,300 years). The use of alternative demographic models with constant or exponentially increasing population size changed the estimate by 10%. A method that does not consider population structure.

The origin was most likely in Mongolia, where the largest number of different star-cluster haplotypes is found. Thus, a single male line, probably originating in Mongolia, has spread in the last ∼1,000 years to represent ∼8% of the males in a region stretching from northeast China to Uzbekistan. According to the study, If the spread were due to a general population expansion, multiple lineages would be expected with the same characteristics of high frequency and presence in multiple populations, but the researchers did not. Thus, the star-cluster pattern is unique.

Several reasons were compared and contrasted by the researchers to come up with the best possible explanation for the rapid spread of the single male line. among the reasons were (1) all populations carrying star-cluster chromosomes could have descended
from a common ancestral population in which it was present at high frequency; (2) many or most Mongols at the time of the Mongol empire could have carried these chromosomes; and (3) it could have been restricted to Genghis Khan and his close male-line relatives, and this specific lineage could have spread as a result of their activities. Their contrast to the first two explanations were: Explanation 1 is unlikely because these populations do not share other Y haplotypes, and explanation 2 is difficult to reconcile with the high Y-haplotype diversity of modern Mongolians.

And thus, starting to learn more about the places and people’s origins may also contain a few surprises. It may come from a simple breakdown of your ethnicity to a whole new star-cluster pattern which dates back to the Monggol Legacy. Genetics never runs out of surprises!

Author: Arian Claudine Esmenos

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