Ancient DNA: How Scientists Read Genomes from 40,000 Years Ago

Ancient DNA: How Scientists Read Genomes from 40,000 Years Ago

In 2010, Svante Paabo and his team at the Max Planck Institute published the first Neanderthal genome. It was a watershed moment, for the first time, we could read DNA from a species that had been extinct for over 30,000 years.

Since then, ancient DNA (aDNA) has exploded. MYDNATLAS now includes 31,989 ancient samples spanning from 45,000 BCE to the Medieval period. But how do scientists extract and sequence DNA from bones that have been underground for millennia?

The Extraction Process

Ancient DNA is incredibly fragile. Over thousands of years, DNA molecules break into tiny fragments, typically just 30-80 base pairs long (modern DNA molecules are billions of base pairs). The extraction process requires extreme care:

1. Sampling: The best DNA comes from the petrous bone (the dense bone behind the ear) and tooth roots. These protect DNA from environmental degradation.
2. Decontamination: The outer surface is removed to eliminate modern DNA contamination from archaeologists and lab workers.
3. Chemical extraction: The bone is dissolved in a buffer solution that releases the trapped DNA fragments.
4. Library preparation: The tiny fragments are converted into sequencing libraries using specialized adapters.
5. Targeted capture: Rather than sequencing the entire genome (expensive), researchers use probes that "fish out" ~1.2 million informative SNP positions.
6. Sequencing: Next-generation sequencers read millions of fragments simultaneously.

The Challenges

Ancient DNA work faces unique challenges:

• Cytosine deamination: The most common damage pattern converts C→T at fragment ends, creating false mutations that must be computationally corrected
• Low coverage: Most ancient samples have 0.1-2x coverage (each position read fewer than twice), compared to 30x for modern genomes
• Contamination: Modern human DNA is everywhere, a single sneeze can contaminate a sample
• Preservation bias: DNA survives best in cold, dry environments. Tropical regions have almost no ancient DNA

What MYDNATLAS Does With Ancient Samples

Each of our 31,989 ancient samples has been processed into G25 coordinates using the same pipeline as modern genomes. This allows direct, mathematically rigorous comparison between you and ancient populations.

Our database includes samples from:

• Harvard David Reich Lab: The largest ancient DNA laboratory in the world
• Max Planck Institute: Svante Paabo's group (Nobel Prize 2022)
• University of Copenhagen: Leading European aDNA center
• Published literature: Every publicly available ancient genome from peer-reviewed publications

Explore Ancient Ancestry on MYDNATLAS

With MYDNATLAS, you can:

• Find your closest ancient matches: Which archaeological individuals are most similar to you?
• Track ancestry through time: See how populations genetically related to you moved across the world
• Compare with specific cultures: Were you closest to Bell Beaker people? Corded Ware? Roman-era Britons?
• Explore the Encyclopedia: Browse detailed profiles for all 31,989 ancient samples with archaeological context

The ancient DNA revolution has given us a time machine for human genetics. MYDNATLAS puts it in your hands.