By Manolya Adan
History has always been a subject taught through textbooks and through the reprisal of written records of history. We have relied on dated documents, anthropogenic and archaeological information to reveal a window into our past. These common sources of historic knowledge can however, leave some things unexplained.
Written history depends on the records of others, data that cannot always be verified, and could indeed be contaminated by bias, propaganda, or quite simply lack of correct information. Such sources of information are also dependent on the observers’ objectivity; it might be difficult to deduce what had been intended as fact or fiction thousands of years ago. A copy of the Da Vinci Code, for example, may well be found in several millennia and interpreted as a component of Christianity.
We now live in a day where everything can be related in some way, and argued through science, and with research from Garrett Hellenthal and his associated, this could now be valid for human history.
Helenthall’s study suggests that we can find our history embedded within our very being. As romantic as this may sound in the modern era, at the height of individualism, multiculturalism, and globalism, the geneticists believe, with just statistical backing, that they have unlocked the key to our past within our DNA. His theories are discussed in the February 14th edition of the journal ‘Science’, in the paper titled: A genetic Atlas of human admixture history.
We can begin to comprehend concepts of admixture through observing wildlife populations on islands. Often the most biodiverse locations on the planet, it was indeed on the Galapagos Islands that Darwin experienced his epiphany whilst observing disparity between the various Finches, hence the birth of evolutionary theory. Oceanic isolation creates the geographic barrier necessary for local adaptations and eventual speciation. Genetic admixture has been described as the interbreeding of 2 or more populations that have previously been separated by geographic barriers such as mountains, oceans and rivers.
Although admixture carries its evolutionary advantages, such as widening of gene pools, which reduces the incidence of heritable diseases and creates genetically divers, robust populations, it is a method of genetic homogenization. In animal populations genetic homogenization can be seen as a barrier to biodiversity, however in humans, it is more than a genetic interaction. It signifies not only the exchange of genes, but of culture, knowledge and language. It is our affinity to remove geographic barriers and unite as a species that has separated us from our Animalian kin, and helped us achieve the things that we have in this current day.
Hellenthall and his team have found a method that has allowed them to map human admixture, showing different global migratory trends. The genetics of 1490 individuals from 95 different countries were sampled, using a complex statistical method called ‘Globetrotter’ to analyze genomic data.
Although the evidence from an individual genome might not be sufficient to make inferences, when observed as a whole, patterns begin to emerge.
Traceable to 4000 years
The research shows that admixed populations hold segments of DNA from all the source groups that have contributed towards their genetic inheritance. The size of this segment decreases over generations of recombination, (further genetic mixing) but traces of the segment persist through the DNA, and can be traceable, at the current level of technology, for up to 4000 years.
Observing a group of individuals from a particular population and finding a common ‘segment’ of DNA, enables geneticists to identify a particular event, and to date it using the segment size concept, accounting for the number of generations that have lapsed since. Also allowing for the fact that migration and admixture can, and probably will have occurred several times, and is likely to involve multiple groups. The tests were run independently of historic knowledge to ensure that scientific bias did not effect the outcome. When the results were later correlated with known dates of true historic events, they were found to have an extremely high incidence of accuracy, as well as being logical in terms of geographic positioning.
Flows of Migration
Multiple waves of admixture have been revealed using this method, including the Bantu expansion into southern Africa. The Bantu expansion was a series of migrations that occurred over a millennium, it is an event that is recorded mostly linguistically, as the languages that are spoken in sub-equatorial Africa bare great resemblances. It had been thought that these cultures could not have diverged more than three thousand years ago, however no archaeological evidence could previously trace the route of expansion but the current research has given a great deal more insight on potential flow of migration than has ever before been seen through archaeological and linguistic evidence alone.
The study also depicts details of events such as European colonialism, the Arab slave trade and the Mongol expansion, where populations including the Hazara people of Pakistan, and the Uygur of the Xinjiang autonomous region in the People’s Republic of China, supporting the notions that both the Hazara and the Uygurs are descendants of Mongolian warriors. The research further depicts that the Mongola admixed westward towards the modern day Turkey, with 8% abundance of Mongolian genetics present in modern day Turks.
The researchers have engineered an interactive atlas available online for people to explore the routes of all nationalities across the globe and observe any potential admixture that may be present within their own genetics. It depicts the effects of trade, slavery, colonization and migration on the genetic mixing of modern humans. It provides a great visual reference to the discoveries unveiled by the research.
This study and similar projects hold a great deal of promise for the future of our knowledge of history. With greater investment into the software used, and with greater sampled populace, the findings of the future investigations could reveal much finer details of the past.
Now that the methodologies have been exacted, we can even begin to delve into ancient DNA, to go even further back in time to see if we can, once and for all, unravel the true story of our evolution as a species. There is nothing to say that this model need be restricted to anthropogenic studies alone, it would in fact be quite possible to develop a greater understanding of any admixture other Animalian species.