DNA barcoding identifies a biological sample by sequencing a short standard stretch of its genome and matching it against reference sequences. This investigation applied the method, using the psbA-trnH region, to twenty five samples of myrrh bought as a commercial commodity, in order to find out which species of Commiphora the modern trade is actually selling.
The samples resolved to three species, Commiphora gileadensis, Commiphora myrrha and Commiphora edulis. Only about eight per cent matched the species named in the pharmacopoeia. In other words the traded material is neither uniform nor reliably the plant the standards specify, and a purchaser of myrrh is buying a category rather than a species.
That result is worth stating on its own terms before any historical question is raised. A resin harvested from related trees across a wide arid region, traded through many hands and sold by appearance and smell, turns out under genetic testing to be a mixture. The finding is about the present day supply chain, it is methodologically straightforward, and it is checkable by anyone willing to repeat the sequencing.
The pharmacopoeia figure is the part with practical consequence beyond the historical question. Where a standard names a species and the traded material largely does not match it, work resting on the assumption that a labelled sample is what it says, in pharmacology, in chemistry or in comparison with ancient descriptions, is resting on less than it appears to. The authors present the barcoding of samples at point of sale as the check that closes that gap.