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Forensic Science Pakistan
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Forensic Science Pakistan

inamgenetics@gmail.com

Discipline

Ancient DNA

Ancient DNA (aDNA) is genetic material recovered from archaeological and historical remains. It reveals how populations moved, mixed and adapted, and it shares its methods with forensic work on degraded remains.

First DNA sequenced from an extinct animalThe quagga
1984
Draft Neanderthal genome published
2010
Years: oldest DNA sequenced from mammoth teeth2021
1M+
Nobel Prize for Svante Pääbo’s work on ancient genomes
2022

Workflow

From bone to genome

  1. Step 01

    Sampling

    The dense petrous bone of the inner ear and tooth roots preserve the most DNA.

  2. Step 02

    Clean-room extraction

    Work happens in dedicated rooms with filtered air, full protective suits and blank controls.

  3. Step 03

    Library preparation

    Fragments are tagged for sequencing; enzyme treatment can remove some damage.

  4. Step 04

    Sequencing or capture

    Shotgun sequencing reads everything; capture enriches for chosen human regions.

  5. Step 05

    Authentication

    Fragment length, damage patterns and contamination estimates confirm the DNA is ancient.

  6. Step 06

    Population analysis

    Genomes are compared with ancient and present-day people to reconstruct history.

History

Milestones in ancient DNA

  1. 1984

    The quagga

    DNA from a museum specimen of an extinct zebra relative is sequenced.

  2. 1985

    An Egyptian mummy

    Svante Pääbo reports DNA cloned from mummified human tissue.

  3. 2010

    Neanderthals and Denisovans

    A draft Neanderthal genome shows they interbred with modern humans; a finger bone reveals the Denisovans.

  4. 2019

    South and Central Asia

    Genomes including ancient individuals from the Swat Valley in Pakistan trace the formation of South Asian populations.

  5. 2021

    Million-year-old DNA

    Mammoth teeth from Siberian permafrost yield the oldest DNA sequenced to date.

Glossary

Key terms

Endogenous DNA
DNA from the individual itself, as opposed to bacteria, soil or handlers.
Deamination
Chemical damage that turns cytosine into uracil, read as C-to-T changes.
Petrous bone
Part of the temporal bone around the inner ear; often the richest source of ancient DNA.
Capture
Enriching a sequencing library for chosen regions using matching probes.

Frequently asked questions

Can ancient DNA survive in Pakistan’s hot climate?

Heat speeds up DNA decay, so preservation is poorer than in cold regions, but careful sampling of petrous bones and teeth has produced genomes from sites such as the Swat Valley.

How is ancient DNA related to forensic work?

Both deal with small amounts of damaged DNA. Methods developed for ancient DNA, such as clean-room protocols and sequencing of short fragments, now help identify old or badly degraded human remains.

References

  1. Higuchi R, Bowman B, Freiberger M, Ryder OA, Wilson AC (1984). DNA sequences from the quagga, an extinct member of the horse family. Nature. doi:10.1038/312282a0
  2. Green RE, Krause J, Briggs AW, et al. (2010). A draft sequence of the Neandertal genome. Science. doi:10.1126/science.1188021
  3. Narasimhan VM, Patterson N, Moorjani P, et al. (2019). The formation of human populations in South and Central Asia. Science. doi:10.1126/science.aat7487
  4. van der Valk T, Pečnerová P, Díez-del-Molino D, et al. (2021). Million-year-old DNA sheds light on the genomic history of mammoths. Nature. doi:10.1038/s41586-021-03224-9

Further reading

Recovering DNA from old bone

Read why the petrous bone is the gold standard for ancient and degraded DNA, and how laboratories use mitochondrial DNA when nuclear DNA fails.