The Human Gut Microbiome is an important host’s component defining its health. These microorganisms are mutualistic symbionts dependent on factors such as host’s age, subsistence models and sociocultural practices, among others. The conjunction of these factors define the microbial ecosystem dynamics. Using a fecal microbiome approach in children, a comparison of two Mexican communities with contrasting lifestyles: “westernized” (Mexico City) and “non-westernized” (Me’phaa indigenous group) was evaluated. The main differences between these two communities are in bacteria associated with different types of diets (high animal protein and refined sugars vs high fiber food, respectively). In addition, the gut microbiome of Me’phaa children showed higher total diversity and the presence of exclusive phyla, such as Deinococcus-Thermus, Chloroflexi, Elusimicrobia, Acidobacteria and Fibrobacteres. In contrast, Mexico City children had less diversity and the exclusive presence of Saccharibacteria phylum which is associated with the degradation of sugar compounds. This comparison allows further exploration of the selective pressures affecting microbial ecosystemic composition over the course of human evolution and the potential consequences of pathophysiological states correlated with westernization lifestyles.