Science 04 Dec 2020: 370(6521): eaaz6827 https://bit.ly/3q47CTG
These authors review the human traits and genes that microbiota may have contributed or altered in response to changes in host diet, climate, or pathogen exposure.
It is now widely recognized that the microbiota of mammals is a product of coevolution. Nevertheless, humans are different in having a geographically specific microbiome and displays community compositions and a range of overlapping and redundant metabolic characteristics that can alter host physiology to become s combined hostmicrobiota entity. Microbiota evolve quickly and can provide capabilities that may be exchanged with other microbiotas, their hosts, and the environment. Microbes evolve faster than their host, which allows them to respond quickly to environmental change. They respond to changes in diet exposure to pathogens such as malaria parasites and changes in local climate.
Evolution of the microbiome, like all biological traits, arises randomly or is adaptive to the environment. Hosts may pass their microbiome to their offspring, which will affect the heritability and transmission modes of these microbes. The authors give the example of lactose digestion via microbial lactase activity in adults resulting from shifts in diet. The allelic variation of these genes also predicts compositional and functional variation of the gut microbiota.
Thus, host genes and the microbiota are linked and interact by dietary adaptations, where host and microbial enzymes metabolize the same dietary components (e.g., fatty acid and alcohol metabolism), through climate-related adaptations. Moreover, microbiota have the potential to affect host evolution by modifying the adaptive landscape.
A better understanding of reciprocal interactions between the host genome and microbiota in the context of adaptive evolution will add another dimension to our understanding of human evolution as we moved with our microbes through time and space.