Considerations of a biochemical nature are presented which show the plurality of exogenous and endogenous factors that may justify the presence of beta-carbolines in human tissues, with specific reference to the cases of encounter of these compounds in South American archaeological findings. With this issue, the aim is to dismantle the Ogalde and coll thesis. (2009) of the old use of ayahuasca (Banisteriopsis caapi) in the Valley of Azapa (Northern Chile); thesis based on the finding of harmine in the hair of two mummies found in this valley.