Frozen fauna – Frossen fauna

Precious white powder

By Jørgen Rosvold
Bone powder from an ancient snow patch find ready for DNA extraction and sequencing. This small sample is enough to provide large amounts of genetic data that can enable us to reconstruct the ancient history of a population. A powder time machine! Photo: Leena Airola, NTNU University Museum

Sampling DNA from ancient bones is an elaborate and time consuming process. Ancient DNA is by definition degraded and due to this special precautions have to be taken. After an animal dies the DNA in its cells quickly starts to degrade and continues to do so over time, leading to loss and fragmentation of DNA. In some bones the DNA is even lost completely. This makes ancient samples prone to contamination from modern DNA and much harder get data from compared to modern samples. Luckily, DNA preserves well in cold environments which makes snow patch finds ideal for studying genetic changes far back in time.

Even so, care has to be taken to avoid contamination and further destruction of the DNA in the bones. That means no snacking on dried reindeer meat while handling old reindeer bones! After they are collected from the snow patches, the finds are slowly dried and then stored in a cooler while they await sampling.

Drilling of bone powder for DNA sampling of an arrowhead made of reindeer bone. Drilling is performed at a very slow speed in order to reduce heat and damage to DNA. In order to avoid contamination with exogenous DNA, work spaces and equipment have to be cleaned and gloves and drill bits changed between every sample. Photo: Leena Airola, NTNU University Museum
Drilling out bone powder with small drill bits instead of cutting of larger pieces is a good way to minimize damage to the ancient bones. Photo: Jørgen Rosvold, NTNU University Museum

After drilling, the samples are ready for a few days of laboratory work with several rounds of chemical treatments including DNA extraction, PCR and eventually sequencing. The end result is hopefully a nice and clean sequence of nucleotides that provides lots of data,


but with ancient samples some days are better than others…


Due to the excellent conditions for preservation in snow patches, the former is luckily usually the case.

For genetic studies on ancient snow patch finds see:

Ancient DNA reveals prehistoric habitat fragmentation and recent domestic introgression into native wild reindeer

Positioning the red deer (Cervus elaphus) hunted by the Tyrolean Iceman into a mitochondrial DNA phylogeny

Modern and ancient DNA reveal recent partial replacement of caribou in the southwest Yukon

Preservation of viral genomes in 700-y-old caribou feces from a subarctic ice patch


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