<p>The gut microbiota is inextricably linked to the host over a long evolutionary process, and the mammalian gut microbiota is the result of the interaction between bacterial species and the host. It plays a vital role in the digestion and absorption of the host, nutrient metabolism, and immune regulation, and the host genetics, diet, age, antibiotic use, and other factors can also cause changes in the gut microbiota. Natural selection serves to maintain a stable dynamic balance between the gut microbiota and the host over an extended period, and the symbiotic system formed by the microbiota and the host under this dynamic equilibrium can clearly indicate the transmission mode of the gut microbiota during the evolutionary process. Hence, the function, influencing factors, and recent advances in the evolution of the gut microbiota in mammals were reviewed, which provides a reference for a deeper understanding of the interaction between the gut microbiota and the host.</p>