The last few months has seen the release of several ground-breaking research studies which are beginning to demystify our ancient origins. This included the first ever complete sequencing of a Neanderthal genome , and two new studies which screened modern genomes for sequences with distinctive Neanderthal features. Now scientists have announced that they have a new technique that enables them to weed out contamination from modern humans in the analysis of ancient DNA.

The new method, described in the journal Proceedings of the National Academy of Sciences, works on very contaminated samples, as well as on incredibly ancient remains. Many years ago, archaeologists would handle fossilised remains without gloves because at the time people did not even know DNA existed. This means that many incredibly precious fossils were contaminated by modern genetic material, which made it virtually impossible to study some of the most tantalizing fossils of ancient humans, which were dug up decades or event centuries ago.

Until now, there hasn’t been a concrete way to distinguish contamination from ancient DNA. With this new technique, scientists will now be to analyse many archaic human fossils which were discovered a long time ago.

Study co-author Pontus Skoglund, a paleogenomics researcher at Uppsala University in Sweden, explained that the new method takes advantage of the fact that DNA degrades in a predictable way over time. Based on the differences between the fossil DNA and the modern genome, and knowing how the DNA nucleotides convert over time, the team can estimate a sample's degradation level, and in turn, its age. The model works even better on very old DNA, because it's more degraded and thus easier to distinguish from modern samples

The technique does, however, face some limitations. For example, some microbial DNA doesn't degrade very much, so the new method could make faulty estimates when studying ancient microbes. It is also very expensive at the moment so it is not easily accessible to wide-scale research just yet.

Scientists have been making huge progress with extracting incredibly old DNA from fossils, such as the 400,000-year-old fossils of mysterious, archaic humans known as Denisovans found in Sima de los Huesos in Spain. The new technique will provide a more accurate way to examine those samples and has the potential to revolutionise the field of archaeology, as well as greatly enhance our understanding of our ancient roots.

By April Holloway