Willerslev had already made groundbreaking contributions to ancient DNA research, including work on Pleistocene animals and early Holocene humans from various parts of the world.

The Mal’ta project was, by the standards of the field at the time of its publication in 2013, among the most technically ambitious ancient genomic analyses attempted.

The researchers extracted DNA from a fragment of arm bone — the humerus — of the Mal’ta boy.

The extraction process requires working in specialized cleanrooms, using equipment and surfaces that have been rigorously decontaminated to prevent the modern DNA of researchers from contaminating the ancient sample.

Ancient DNA is present in very small quantities and is highly degraded — broken into short fragments that must be carefully assembled computationally into something resembling the original sequence.