Ancient poop tells story of how urbanisation changed the intestine
Research by US scientists into the composition of dried human faeces from archeological sites shows that the increasingly urban and cosmopolitan way of modern life has led to dramatic changes in the make-up of human intestinal flora.
Raul Tito and his colleagues from the University of Oklahoma analysed the microbial composition of coprolite samples (faeces retrieved from archaeological contexts) from three locations in the Americas.
The sites were chosen because they provided a broad range of environmental conditions.
The samples taken from Hinds Cave in the southwestern United States were the oldest, at around 8,000 years, while those recovered from Rio Zape in northern Mexico were 1,400 years old.
The samples taken from naturally preserved mummies in Caserones in northern Chile were 1,600 years old.
Thanks to DNA testing, it was shown that the bacterial composition of the Rio Zape samples had similarities to those taken from children living in a rural African village, the researchers reported in a paper published in the PLOS ONE online science journal.
Tests on the samples from the other two sites showed no similarities with the composition of the intestinal flora of a typical adult American.
Researchers also compared the results with the intestinal flora data taken from Oetzi, the mummified prehistoric man found on a European mountaintop, as well as those from the body of an Austrian soldier frozen in a glacier almost a century ago.
These results also bore the closest resemblance to the intestinal flora of rural children, the scientists concluded.
“These results indicate that our modern, cosmopolitan lifestyle has dramatically changed the human intestinal flora,” explained the article’s main author Cecil Lewis.
The researchers also argue that that modern use of antibiotics has wreaked havoc on the health and content of our gut bacteria, increasing susceptibility to autoimmune diseases and other sicknesses.