Earlier genetic research involving hair from historical figures — including some research on Sitting Bull’s hair in earlier decades — was typically limited to mitochondrial DNA analysis, which could establish maternal lineage connections (because mitochondrial DNA is inherited through the mother) but could not address the full range of familial relationships.

The technique applied in the more recent study was specifically designed to go beyond mitochondrial analysis and recover autosomal DNA — the nuclear DNA on the non-sex chromosomes that carries information about both paternal and maternal lineages and can be used to assess a broader range of familial relationships.

The recovery of usable autosomal DNA from hair preserved for more than a century required a combination of technical approaches.

Library preparation — the process of converting DNA fragments into a form suitable for sequencing — was adapted to work with the very short fragments that survive in degraded material.