The new research by Tanya Yatsunenko and colleagues examining gut microbiomes in different human populations is just incredibly cool work
The population genomics of these gut microbes is a great topic also, but what I find most interesting is the parallel ontogenetic changes among populations from infants to adults:
The guts of babies are dominated by Bifidobacterium the group thats commonly found in probiotic foods. Theyre also loaded with genes for producing folate, an essential B-vitamin thats involved in creating and repairing DNA. These folate-making genes decline as babies grow up, and get more of the vitamin from their diets. At the same time, the genes for making other vitamins, like B1, B7 and especially B12, become more common. This similarity across cultures in building up the gut microbiome in childhood has been touched on before but its much more convincing here, says Peer Bork, from the European Molecular Biology Laboratory.
Adam Van Arsdale also has written up some thoughts about the research: “The human gut microbiome”.