But as noted above, these features are unreliable in young children.

The markers that allow reliable sex estimation in adult skeletons — the shape of the pelvic inlet and outlet, the greater sciatic notch, the mastoid process, the supraorbital ridge — are either absent or far less pronounced in juvenile individuals.

Studies of osteological sex estimation in children have found significant error rates, particularly for younger age groups.

This means that earlier assessments of the sex distribution of the chultún remains, based on skeletal morphology, may have been incorrect or at least uncertain.

Ancient DNA provided an independent, objective, and highly reliable method for establishing biological sex — one that did not depend on the difficult judgment calls that juvenile osteology requires.