The researchers who worked on the Chichén Itzá chultún samples used extraction methods optimized for low-yield material, including digestion in silica-containing buffers and library preparation techniques designed to capture very short and highly fragmented DNA molecules — the kinds of fragments that survive when most of the original DNA has already been degraded.

The success rate of 64 out of the total samples processed represents a significant achievement for this type of material.

Not every sampled petrous bone yielded sufficient DNA for genome-wide analysis; the 64 successful samples were those where enough genetic material survived to produce the data needed for kinship analysis and population genetic work.

The genome-wide data generated from each successful sample consisted of sequencing reads — short stretches of DNA sequence — that could be mapped to the human reference genome to determine which part of the genome they came from.

The depth of coverage — how many times on average each position in the genome was represented — varied among the samples, and the specific analyses that could be conducted depended on the coverage achieved for each individual.