And crucially, his DNA was extracted from the root of his tooth, not from bone or soft tissue.

Teeth are increasingly recognized as among the best sources of ancient DNA, for a reason that is both elegant and obvious in retrospect: enamel, the hardest substance the human body produces, is a physical barrier against bacterial invasion.

The microorganisms that colonize remains after death and begin breaking down biological material can destroy DNA in bone and muscle far faster than they can penetrate the dental enamel.

The pulp inside the tooth, protected by that enamel shell, can retain readable genetic material long after everything around it has been chemically altered.