But the same process that preserved the bodies may have, paradoxically, damaged the genetic material inside them.

The natron treatment that desiccated the body and inhibited bacterial decomposition was chemically active in ways that could alter and degrade DNA.

The oils and resins sometimes applied during mummification could chemically modify biological material in ways that compromised genetic analysis.

The elaborate wrapping and storage created conditions that, while excluding some environmental factors, may have created others.

Perhaps more importantly, the mummies most studied — the most elaborate, the most carefully preserved — were typically from the highest social strata, whose tombs were precisely the most visited, the most handled, and the most contaminated by centuries of human activity.

The DNA of an elite mummy may have been compromised by the attentions of grave robbers, archaeologists, museum curators, and researchers long before anyone with proper ancient DNA protocols thought to look at it.