The retrieval of ancient human DNA sequences

Area of Science:

• Paleogenomics
• Molecular Anthropology
• Archaeological Science

Background:

• Ancient human remains provide insights into past populations.
• DNA extraction and amplification from ancient samples are challenging due to degradation and contamination.

Purpose of the Study:

• To investigate methods for ensuring the authenticity of DNA sequences amplified from ancient human remains.
• To evaluate the impact of starting molecule numbers on PCR amplification accuracy.

Main Methods:

• DNA extraction from 600-year-old human remains.
• Polymerase Chain Reaction (PCR) amplification of mitochondrial DNA (mtDNA) fragments.
• Direct sequencing and cloning of PCR products.
• Quantification of amplifiable DNA molecules.

Main Results:

• Direct sequencing of amplified fragments from ancient DNA often yielded multiple, mixed sequences.
• Amplifications initiated with few DNA molecules (<40) resulted in diverse and unreliable sequences.
• Amplifications initiated with a higher number of molecules (thousands) produced unambiguous and reproducible results.

Conclusions:

• Ensuring the authenticity of ancient DNA sequences requires rigorous experimental protocols.
• Quantification of amplifiable DNA molecules is essential for identifying and mitigating contamination and PCR errors.
• Adequate starting material is critical for reliable ancient DNA analysis.