From C. Heneghan:

Re: Study explores how Inca kids were drugged for sacrifice (July 29, 2013): This report seems to assume that the levels of drugs found in Inca children’s hair can be taken to be abnormal, and indicates drug use to prepare for sacrifice. Unfortunately no comment is included regarding controls, nor is there comment regarding whether Inca children might all have had similar concentrations of the alcohol and coca metabolites. The only valid conclusion based on the data in your report is that there was probably an increase in alcohol intake in one of the children shortly before death. It is entirely possible that all the other findings would be replicated in non-ritually killed individuals, and represent normal drug intake for Inca children at that time.