Ancient DNA Glossary: Key Terms Explained

Reference guide · Updated 2026

A plain-language reference for the genetic genealogy and ancient DNA terms used throughout this site. For deeper dives into any specific topic, follow the linked guides within each definition.

Admixture

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The mixing of two or more previously separated populations through interbreeding, resulting in descendants who carry ancestry from all of the source populations. Most modern human populations are the product of multiple historical admixture events.

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Ancient DNA (aDNA)

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DNA recovered from archaeological or paleontological remains — bones, teeth, or other preserved tissue — rather than from living individuals. Ancient DNA is typically degraded and fragmented, requiring specialized lab techniques to sequence.

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Autosomal DNA

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DNA found on the 22 pairs of non-sex chromosomes, inherited roughly equally from both parents. Most consumer ancestry-percentage estimates are based on autosomal DNA, since it reflects input from many ancestral lines rather than just one.

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Bottleneck (genetic)

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A sharp reduction in a population's size that reduces its overall genetic diversity, sometimes followed by later re-expansion from the smaller surviving group. Several ancient haplogroups show evidence of historical bottlenecks.

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Founder effect

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A loss of genetic diversity that occurs when a new population is established by a small number of individuals from a larger source population, causing the new population's gene pool to reflect only a subset of the original diversity.

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Haplogroup

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A group of individuals who share a common ancestor on a single line of descent, defined by a set of shared genetic mutations. Y-DNA haplogroups trace direct paternal lines; mtDNA haplogroups trace direct maternal lines. See our full haplogroup explainer.

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mtDNA (mitochondrial DNA)

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DNA located in the mitochondria (a cell's energy-producing structures) rather than the cell nucleus, inherited essentially unchanged from mother to child. Used to trace direct maternal-line ancestry.

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Neolithic

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The "New Stone Age," the period marked by the transition from hunting and gathering to settled farming, beginning roughly 10,000–12,000 years ago in the Near East and spreading gradually to other regions.

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Paleogenomics

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The scientific field focused on sequencing and analyzing whole genomes recovered from ancient remains, as distinct from the narrower field of ancient DNA analysis focused on smaller genetic markers.

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Reference panel

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A curated set of DNA samples from individuals with known or well-documented ancestry, used by testing companies and researchers as a comparison baseline when estimating an individual's ancestry composition.

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Runs of homozygosity (ROH)

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Long stretches of DNA where the copies inherited from each parent are identical, typically indicating that the parents share relatively recent common ancestry. Long ROH segments can suggest recent inbreeding or a small founding population.

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Steppe ancestry

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Ancestry derived from Bronze Age pastoralist populations of the Pontic-Caspian steppe, most closely associated with the Yamnaya culture, whose descendants spread widely across Europe and parts of Asia beginning around 3000 BCE. See our full guide.

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Whole-genome sequencing (WGS)

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A sequencing method that reads essentially the entire genome of an organism, as opposed to targeting only specific regions. High-coverage ancient genomes sequenced this way allow much more detailed ancestry and trait analysis than earlier, lower-resolution methods.

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Yamnaya

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A Bronze Age pastoralist culture of the Pontic-Caspian steppe (roughly modern Ukraine and southern Russia), whose descendants carried steppe ancestry into Europe, Central Asia, and South Asia beginning around 3000 BCE. See our Bronze Age Steppe ancestry guide.

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Y-DNA

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DNA located on the Y chromosome, passed from father to son largely unchanged. Used to trace direct paternal-line ancestry through Y-DNA haplogroups.

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