ntRoot: computational inference of human ancestry at scale from genomic data
Bibliographic record
Abstract
Abstract Motivation Ancestry information is essential to large cohort studies but is often unavailable or inconsistently measured. For studies involving genome sequencing, existing ancestry prediction methods are constrained by computational demands and complex input requirements. Efficient, scalable approaches are needed to infer ancestry directly from sequencing data while maintaining accuracy and reproducibility. Results We present ntRoot, a computationally lightweight method for inferring human super-population-level ancestry from whole genome assemblies or short or long sequencing data. Utilizing a reference-guided, alignment-free single nucleotide variant detection framework, ntRoot employs a succinct Bloom filter to efficiently query diverse genomic inputs against a variant reference panel with known genotypes and ancestry. Demonstrated on over 600 human genome samples, including complete genomes, draft assemblies, and 280 independently generated samples, ntRoot accurately predicts geographic labels and shows high concordance with traditional methods such as ADMIXTURE (R2 = 0.9567) when estimating ancestry fractions. Analyses complete within 30 minutes for assemblies and 75 min for 30-fold sequencing data using 13–68 GB of memory. ntRoot provides global and local ancestry inference, delivering high-resolution predictions across genomic loci. This paradigm fills a critical gap in cohort studies by enabling rapid, resource-efficient, and accurate ancestry inference at scale, advancing ancestry characterization in genomic research. Availability ntRoot is freely available on GitHub (https://github.com/bcgsc/ntroot).
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.004 | 0.026 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.002 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.003 | 0.003 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.016 | 0.007 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".