Archaeological Genetics: It's Not All as Old as It at First Seems
May 20, 2013 — Genomic analyses suggest that patterns of genetic diversity which indicate population movement may not be as ancient as previously believed, but may be attributable to recent events. This study published in BioMed Central's open access journal Investigative Genetics, based in the Netherlands, is able to genetically characterize geographically separated subpopulations within the country and map them to population movement within the last 2000 years.
8Looking at more than 400,000 SNPs (genetic variations) of almost 1000 people across the Netherlands, this study found that the genomic diversity across the Netherlands follows a southeast to northwest gradient and that the Dutch population could be separated out genetically into four geographic groups (south, north, central-west and central-north).
These results could be explained by invoking movement of ancient, Paleolithic-Neolithic humans, similar to that proposed to explain the genetic diversity across central entire Europe. However the data also fits a model involving movement of people within the last 70 generations of modern Dutch, for which there is a wealth of archaeological evidence.
Prof Manfred Kayser from the Erasmus University Medical Center in Rotterdam, who led the study, commented, "Because of the overwhelming geological and archaeological records for strong genetic discontinuities we explain our findings by recent rather than ancient events in Dutch population history. Our results not only are of epidemiological and forensic relevance but additionally highlight that future population history studies need to take into account recent demography before assuming all genetic variation observed is due to ancient events."
Viking DNA Retrieved From 1,000-Year-Old Skeletons
May 28, 2008 — Although "Viking" literally means "pirate," recent research has indicated that the Vikings were also traders to the fishmongers of Europe. Stereotypically, these Norsemen are usually pictured wearing a horned helmet but in a new study, Jørgen Dissing and colleagues from the University of Copenhagen, investigated what went under the helmet; the scientists were able to extract authentic DNA from ancient Viking skeletons, avoiding many of the problems of contamination faced by past researchers.
Analysis of DNA from the remains of ancient humans provides valuable insights into such important questions as the origin of genetic diseases, migration patterns of our forefathers and tribal and family patterns.
Unfortunately, severe problems connected with the retrieval and analysis of DNA from ancient organisms (like the scarcity of intact molecules) are further aggravated in the case of ancient humans. This is because of the great risk of contamination with abundant DNA from modern humans. Humans, then, are involved at all steps, from excavation to laboratory analyses. This means that many previous results have subsequently been disputed as attributed to the presence of contaminant DNA, and some researchers even claim that it is impossible to obtain reliable results with ancient human DNA.
Using freshly sampled material from ten Viking skeletons from around AD 1,000, from a non-Christian burial site on the Danish island of Funen, Dissing and colleagues showed that it is indeed possible to retrieve authentic DNA from ancient humans.
Wearing protective suits, the researchers removed the teeth from the jaw at the moment the skeletons were unearthed when they had been untouched for 1,000 years. The subsequent laboratory procedures were also carefully controlled in order to avoid contamination.
Analysis of the Viking DNA showed no evidence of contamination with extraneous DNA, and typing of the endogenous DNA gave reproducible results and showed that these individuals were just as diverse as contemporary humans. A reliable retrieval of authentic DNA opens the way for a valuable use of prehistoric human remains to illuminate the genetic history of past and extant populations.
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