| The completion of the human genome sequencing | | | | present, permitting inference of human evolution, |
| project was the first step in allowing scientists to | | | | population affinity and demographic history (358). |
| unravel the secrets contained in our DNA. Further | | | | Their report was based upon "the analysis of |
| over the past few years DNA testing has | | | | 1062 globally representative individuals" (Underhill |
| become affordable and easy to do. This has | | | | 358). They concluded that the subjects "represent |
| spawned the practice of performing DNA testing | | | | the descendants of the most ancestral |
| for Genealogical purposes which is called Genetic | | | | patrilineages of anatomically modern humans that |
| Genealogy. | | | | left Africa between 35,000 and 89,000 years |
| One of the first genetic genealogy studies was | | | | ago" (Underhill 358). |
| conducted in the late 1980s by scientists with the | | | | So far genetic genealogy research has focused on |
| Department of Biochemistry at the University of | | | | these two kinds of DNA. As mentioned previously |
| California, Berkeley. These scientists Rebecca L. | | | | mtDNA is passed along the maternal line and |
| Cann, Mark Stoneking and Allan C. Wilson studied | | | | Y-Chromosome DNA is passed along the paternal |
| a newly discovered kind of DNA. Mitochondrial | | | | line. These two kinds of DNA effectively |
| DNA (mtDNA) is contained not in the nucleus of | | | | encompass all of our ancestors. Yet they provide |
| our cell, but in the mitochondria organelles of our | | | | no information about our ancestors inside the |
| cells. These scientists chose to study Mitochondrial | | | | encompassed area. For example our maternal |
| DNA (mtDNA) because of its three unique | | | | grandfather (mother's father) couldn't contribute |
| properties which they explain as: | | | | any mtDNA or Y-Chromosome DNA to our |
| First, mtDNA gives a magnified view of the | | | | mother. Yet he did contribute a third type of DNA |
| diversity present in the human gene pool, because | | | | called autosomal DNA. This type of DNA has yet |
| mutations accumulate in this DNA several times | | | | to be studied for Genetic Genealogy purposes |
| faster than in the nucleus. Second, because | | | | because of its inherent difficulties. |
| mtDNA is inherited maternally and does not | | | | The main reason autosomal DNA is just now |
| recombine, it is a tool for relating individuals to one | | | | being studied is because scientists aren't sure how |
| another. Third, there are about 1016 mtDNA | | | | to determine which autosomal DNA came from |
| molecules within a typical human and they are | | | | mom and which came from dad without testing |
| usually identical to one another (Cann 31). | | | | one or both of our parents. This situation is |
| They extracted and compared mtDNA from "147 | | | | illustrated by the mathematical equation X = Xm |
| people, drawn from five geographic populations" | | | | 2 + Xd/2 where our autosomal DNA (X) is half of |
| (Cann 31). The researchers discovered that "All | | | | our mom's (Xm/2) and half of our dad's (Xd/2). |
| these mitochondrial DNAs stem from one woman | | | | By testing ourselves we identify our autosomal |
| who is postulated to have lived about 200,000 | | | | DNA but can't determine which part came from |
| years ago, probably in Africa" (Cann 31). Their | | | | mom or dad. Additionally testing one of our |
| findings also agree with the archaeology record as | | | | parents is necessary to determine exactly which |
| Cann explains "Studies of mtDNA suggest a view | | | | parent contributed which part of our autosomal |
| of how, where and when modern humans arose | | | | DNA. This type of testing is currently used for |
| that fits with one interpretation of evidence from | | | | Paternity and near relationship testing. But quickly |
| ancient human bones and tools" (36). | | | | becomes impractical after a few generations |
| Swedish researchers Max Ingman, Henrik | | | | because of the difficulty of obtaining DNA samples |
| Kaessmann, Svante Paabo and Ulf Gyllensten | | | | from probably deceased ancestors. |
| critical of these findings conducted their own | | | | Conclusion |
| study in 2000. They claimed that "almost all | | | | Genetic Genealogy is the science of analyzing |
| studies of human evolution based on mtDNA | | | | DNA for genealogical purposes. Studies have |
| sequencing have been confined to the control | | | | shown that we all stem from a common female |
| region, which constitutes less than 7% of the | | | | and male ancestor. Because this emerging science |
| mitochondrial genome" (Ingman 708). Further they | | | | is so new, benefits of this research are still being |
| argued that the prior methods of analysis where | | | | identified. Currently I believe Genetic Genealogy |
| "providing data that are ill suited to estimations of | | | | offers three categories of benefits. |
| mutation rate and therefore the timing of | | | | First is entertainment value. Finding out you're |
| evolutionary events" (Ingman 708). So they | | | | related to famous people like George Washington, |
| decided to study the complete mtDNA sequence | | | | Julius Caesar or Genghis Khan is just plain fun. |
| from 53 people of various races. | | | | Imagine the bragging rights and small-talk fodder |
| Surprisingly their attempt to discredit the previous | | | | this provides at social gatherings. |
| research failed as they also came to roughly the | | | | Second is scientific value. Current studies have |
| same conclusions. They conceded to the likely | | | | corroborated other scientific findings such as the |
| hood of a common ancestor shared by all the | | | | human archaeological record. Medical sciences will |
| subjects despite being "geographically unrelated" | | | | benefit from correlating DNA studies with family |
| (Ingman 712). They estimated "The age of the | | | | genealogies to isolate hereditary diseases. |
| most recent common ancestor (MRCA) for | | | | Third is relatedness value. Finding out you're |
| mtDNA, on the basis of the maximum distance | | | | related to a wealthy individual like Bill Gates may |
| between two humans...to be 171,500" (Ingman | | | | entail a financial windfall. Most importantly of all is |
| 712) instead of the earlier estimate of 200,000 | | | | the ability to reunite families. Millions of displaced |
| years ago. But they refused to align their findings | | | | war torn families and adopted children can now |
| with archeologists by stating "Whether the | | | | turn to Genetic Genealogy to find their relatives. |
| ancestors of these six extant lineages originally | | | | Sources |
| came from a specific geographic region is not | | | | Cann, Rebecca L. et al. "Mitochondrial DNA and |
| possible to determine" (Ingman 712). Lastly they | | | | human evolution." Nature 325 (1987): 31-36 |
| agreed on the potential of genetic genealogy by | | | | Carmichael, Terrence and Alexander Kuklin. How |
| summarizing: | | | | to DNA Test our Family Relationships? California: |
| Our results indicate that the field of mitochondrial | | | | AceN Press, 2000 |
| population genomics will provide a rich source of | | | | Cavalli-Sforza, L. Luca et al. The History and |
| genetic information for evolutionary studies. | | | | Geography of Human Genes. New Jersey: |
| Nevertheless, mtDNA is only one locus and only | | | | Princeton University Press, 1994 |
| reflects the genetic history of females. For a | | | | Ingman, Max et al. "Mitochondrial genome variation |
| balanced view, a combination of genetic systems | | | | and the origin of modern humans." Nature 408 |
| is required. With the human genome project | | | | (2000): 708-713 |
| reaching fruition, the ease by which such data | | | | Tooker, Elisabeth. An Ethnography of the Huron |
| may be generated will increase, providing us with | | | | Indians, 1615-1649. New York: Syracuse University |
| an evermore detailed understanding of our genetic | | | | Press, 1991 |
| history (Ingman 712). | | | | Underhill, Peter A. et al. "Y chromosome sequence |
| Their call for a more balanced view was shortly | | | | variation and the history of human populations." |
| answered because in 2000 a team of researchers | | | | Nature Genetics 26 (2000): 358-361 |
| from the Department of Genetics at Stanford | | | | Walsh, Bruce. "Estimating the Time to the Most |
| University lead by Peter A. Underhill published their | | | | Recent Common Ancestor for the Y |
| results of studying Y-chromosome DNA. Only | | | | chromosome or Mitochondrial DNA for a Pair of |
| males have the Y-chromosome which has unique | | | | Individuals." Genetics 158 (2001): 897-912 |
| properties as explained by Underhill: | | | | Zimmer, Carl. "After You, Eve." Natural History 3 |
| Binary polymorphisms associated with the | | | | (2001): 32-35 |
| non-recombining region of the human Y | | | | Garon Yoakum is a representative for Relative |
| chromosome (NRY) preserve the paternal genetic | | | | Genetics. |
| legacy of our species that has persisted to the | | | | |