Fragment length distribution: Ancient DNA fragments are characteristically short, because degradation breaks the long DNA molecules into small pieces over time.

The NUE001 data shows the expected distribution of short fragment lengths, inconsistent with modern contamination (which would consist of longer, intact DNA).

Consistency across multiple analytical approaches: The ancestry inferences from the autosomal genome, the mitochondrial DNA haplogroup, and the Y-chromosome haplogroup are all consistent with each other and with the overall picture of an individual of North African and West Asian ancestry.

If the result were an artifact of contamination, this consistency across independent lines of evidence would be unlikely.