Preceramic transhumance and andean food production

Thomas Lynch (1971) has recently attempted to document the fact that the preceramic hunter-gatherers of Peru were mobile throughout a range of altitudinal zones and that the fields of movement of these preceramic populations may well have been continuous, since the members of each group exploited the resources of different habitats in terms of regular annual cycles. However, it is equally clear that these long, linear fields of the preceramic populations began to be fragmented at some point in lime. We believe that the termination of the proposed period of transhumance constitutes an extremely interesting problem. At the present time this feature has been discussed only in terms of data from the Peruvian coast. In this paper we employ some of Lynch’s data and observations in an attempt to demonstrate (I) that a minimum of modification of the preceramic pattern of food procurement within the highlands was required to convert hunter-gatherers into food producers; and (2) wild tubers played a crucial role in this process.     

Lack of Chemically Induced Mutation in Repair-Deficient Mutants of Yeast

Two genes, rad6 and rad9, that confer radiation sensitivity in the yeast Saccharomyces cerevisiae also greatly reduce the frequency of chemically-induced reversions of a tester mutant cyc1-131, which is a chain initiation mutant in the structural gene determining iso-1-cytochrome c. Mutations induced by ethyl methanesulfonate (EMS), diethyl sulfate (DES), methyl methanesulfonate (MMS), dimethyl sulfate (DMS), nitroquinoline oxide (NQO), nitrosoguanidine (NTG), nitrogen mustard (HN2), beta-propiolactone, and tritiated uridine, as well as mutations induced by ultraviolet light (UV) and ionizing radiation were greatly diminished in strains homozygous for either the rad6 or rad9 gene. Nitrous acid and nitrosoimidazolidone (NIL), on the other hand, were highly mutagenic in these repair-deficient mutants, and at low doses, these mutagens acted with about the same efficiency as in the normal RAD strain. At high doses of either nitrous acid or NIL, however, reversion frequencies were significantly reduced in the two rad mutants compared to normal strains. Although both rad mutants are immutable to about the same extent, the rad9 strains tend to be less sensitive to the lethal effect of chemical mutagens than rad6 strains. It is concluded that yeast requires a functional repair system for mutation induction by chemical agents.