Recently, Sutter and Mertz (2004) studying non metric cranial traits in prehistoric groups from northern Chile were unable to find significant variation from the coastal Archaic to the Lite Intermediate in the Azapa Valley. in contrast with our findings which indicate the existence of an important microevolutionary process. The objects of this study is to provide an explanation for the observed discrepancy between our results and those of Sutter and Mertz (2004), to comment oil the new results of Sutter (2006) in all effort to enrich the discussion concerning the prehistoric population dynamics of the Azapa valley region and to summerize findings in order to achieve a synthesis. In order to accomplish these goals it was found convenient to perform a comparative analysis of cranial metrical and non metrical variation of the prehistoric groups oil which published inferences were based, as well (is an evaluation of the statistical methodology employed by the above mention authors.