Western South America was one of the worldwide cradles of civilization. The well-known Inca Empire was the tip of the iceberg of an evolutionary process that started 11,000 to 14,000 years ago. Genetic data from 18 Peruvian populations reveal the following: 1) The between-population homogenization of the central southern Andes and its differentiation with respect to Amazonian populations of similar latitudes do not extend northward. Instead, longitudinal gene flow between the northern coast of Peru, Andes, and Amazonia accompanied cultural and socioeconomic interactions revealed by archeology. This pattern recapitulates the environmental and cultural differentiation between the fertile north, where altitudes are lower, and the arid south, where the Andes are higher, acting as a genetic barrier between the sharply different environments of the Andes and Amazonia. 2) The genetic homogenization between the populations of the arid Andes is not only due to migrations during the Inca Empire or the subsequent colonial period. It started at least during the earlier expansion of the Wari Empire (600 to 1,000 years before present). 3) This demographic history allowed for cases of positive natural selection in the high and arid Andes vs. the low Amazon tropical forest: in the Andes, a putative enhancer in HAND2-AS1 (heart and neural crest derivatives expressed 2 antisense RNA1, a noncoding gene related to cardiovascular function) and rs269868-C/Ser1067 in DUOX2 (dual oxidase 2, related to thyroid function and innate immunity) genes and, in the Amazon, the gene encoding for the CD45 protein, essential for antigen recognition by T and B lymphocytes in viral–host interaction.

南美洲西部是世界文明的摇篮之一。著名的印加帝国只是 11,000 到 14,000 年前开始的进化过程的冰山一角。来自 18 个秘鲁种群的遗传数据揭示了以下内容：1）安第斯山脉中南部的种群间同质化及其相对于相似纬度的亚马逊种群的分化并未向北延伸。相反，秘鲁北部海岸、安第斯山脉和亚马逊河流域之间的纵向基因流动伴随着考古学揭示的文化和社会经济相互作用。这种模式概括了海拔较低的肥沃北部和安第斯山脉较高的干旱南部之间的环境和文化差异，作为安第斯山脉和亚马逊河流域截然不同的环境之间的遗传屏障。2）干旱的安第斯山脉人口之间的遗传同质化不仅是由于印加帝国或随后的殖民时期的迁移。它至少开始于瓦里帝国早期扩张期间（距今 600 至 1000 年）。3）这种人口历史允许在高干旱的安第斯山脉与低亚马逊热带森林中进行积极自然选择的案例：在安第斯山脉，推定的增强剂HAND2-AS1 （心脏和神经嵴衍生物在DUOX2（双氧化酶 2，与甲状腺功能和先天免疫相关）基因中表达 2 个反义 RNA1，一种与心血管功能相关的非编码基因）和 rs269868-C/Ser1067 ，在亚马逊，编码CD45蛋白的基因，在病毒-宿主相互作用中对T淋巴细胞和B淋巴细胞的抗原识别至关重要。