Gut bacteria have co-evolved with humans over millions of years and helped them adapt to new environments and foods. For the first time, an international team of researchers has deciphered the intestinal bacteria of present-day hunter-gatherers.
The Hadza community of Tanzania harbours a unique microbial profile with features yet unseen in any other human group.
The findings show that the Hadza have a more diverse gut microbe ecosystem.
"This is extremely relevant for human health.
Several diseases like irritable bowel syndrome, colorectal cancer, obesity, type II diabetes, Crohn's disease and others are significantly associated with a reduction in gut microbial diversity," explained Stephanie Schnorr from the Max Planck Institute for Evolutionary Anthropology in Germany.
This offers a rare opportunity for scientists to learn how humans survive by hunting and gathering in the same environment and using similar foods as our ancestors did.
The study further shows how gut microbiota may have helped our ancestors adapt and survive during the Paleolithic period or old Stone Age - the earliest period of human development and the longest phase of mankind's history.
The Hadza gut microbiota is well suited for processing indigestible fibres from a plant-rich diet and likely helps the Hadza get more energy from the fibrous foods that they consume.
Surprisingly, Hadza men and women differed significantly in the type and amount of their gut microbiota, something never before seen in any other human population.
Hadza men hunt game and collect honey, while Hadza women collect tubers and other plant foods.
"The differences in gut microbiota between the sexes reflects this sexual division of labour. It appears that women have more bacteria to help process fibrous plant foods, which has direct implications for their fertility and reproductive success," Schnorr noted.
The Hadza experience little to no autoimmune diseases that would result from gut bacteria imbalances, said the study published in the journal Nature Communications.
"Genetic diversity of bacteria is likely the most important criterion for the health and stability of the gut microbiome. Co-resident microbes are our 'old friends' that help us adapt to different lifestyles and environments", said Amanda Henry, leader of the Max Planck Research Group on Plant Foods.