The microbiome changes as our diet alters during our lifetime—from consuming breast milk, to eating soft foods and then solids, and finally vegetables and meats.
But eating a poor diet creates a poorly-functioning microbiome that affects the way our immune system deals with viruses and bugs.
The good news is that we can change our microbiome by improving our diet, as researchers from Stanford University School of Medicine discovered when they researched four communities living in the Himalayas. The Raute and the Raji communities have farmed for the past 40 years, the Tharu for 300 years, while the Chepang are still hunter-gatherers.
The gut microbiomes of each community differed, although the Rautes' and Rajis' was similar. "Human microbiomes may have changed gradually as human lifestyle changed, and these changes can happen within a human's lifetime", said researcher Aashish Jha.
The discovery echoes that made by earlier studies, which noted that the microbiomes of indigenous populations in Africa and South America differed from those in industrialised Western countries.
It also throws into question what it is that makes us 'tick'. The standard model has it that we are made up of the genetic coding of our DNA, but these new discoveries suggest that we are more microbial—and changeable over very short time periods.