Shifting Climates, Foods, and Diseases: The Human Microbiome through Evolution

Human evolution has been punctuated by climate anomalies, structuring environments, deadly infections, and altering landscapes. How well humans adapted to these new circumstances had direct effects on fitness and survival. Here, how the gut microbiome could have contributed to human evolutionary success through contributions to host nutritional buffering and infectious disease resistance is reviewed. How changes in human genetics, diet, disease exposure, and social environments almost certainly altered microbial community composition is also explored. Emerging research points to the microbiome as a key player in host responses to environmental change. Therefore, the reciprocal interactions between humans and their microbes are likely to have shaped human patterns of local adaptation throughout our shared evolutionary history. Recent alterations in human lifestyle, however, are altering human microbiomes in unprecedented ways. The consequences of interrupted host–microbe relationships for human adaptive potential in the future are unknown. Humans live in a microbial world including microbial communities living on the body mucosal surfaces. This microbiome provides essential metabolic activities, and has played a key role in adaptation to nutritional and climatic changes during human evolution. This microbiome protects humans against pathogens, but can affect or modulate the expressivity of susceptibility to inflammatory and metabolic diseases.