Recent archaeological research in the Andean highlands of Central Chile provides evidence that hunter-gatherers of the Archaic IV period incorporated knowledge and use of initial cultigens into their subsistence system. At the archaeological site of El Plomo (3,460-3,340 years cal BP), located at 2,070 m above sea level, charred and desiccated small fruits of Chenopodium (cf Chenopodium quinoa), ranging from 0,8 to 1 mm in diameter, have been documented. Morphological analyses perfonned on the desiccated fruits suggest that their sizes parallel those of Chenopodium pallidicaule or canihua, or correspond to an early variety of quinoa. The absence of testa or other diagnostic characteristics of these fruits makes any secure species identification difficult. This new finding opens a new line in the discussion of Chenopodium domestication in Central Chile. Additionally, we propose that other plant resources that had not been considered as foodstuffs by scholars in previous studies were used by the late hunter-gatherers in this region. The Alto Maipo location in Central Chile is suggested to have been an ecological and cultural threshold where hunter-gatherers of the Archaic IV period introduced a significant innovation into their basic subsistence system.