The human gut houses a great quantity of living organisms in the form of bacteria that generate a number of effects on the body. A new study now suggests that some of these living things might constitute a different life form altogether; one that does not fall into the 3 main broad categories, namely bacteria, archaea, and eukaryotes. The scientific paper is published in the journal Biology Direct.
Researchers from the Pierre and Marie Curie University in France initially aimed at restructuring the classification system of the organisms residing in the human colon. When they analysed 86 gene families to achieve this end, they came across sequences of DNA that do not correspond with what we normally know of the three domains of life (bacteria, archaea, and eukaryotes).
All living organisms are thought to fall into either one of the three groups, each having specific characteristics. The discovery of the team from Paris, however, appears to point at a fourth category.
While their findings are not conclusive – the three domains might have genetic features that are unknown to us – the degree of difference between the genes they found and the known ones is quite queer.
The researchers collected 230,000 DNA sequences related to known ones from the 86 gene families from the gut microbiome. The former sequences were then analysed further, thereby unveiling 80,000 pieces of microbial DNA belonging to the 86 gene families. However, around 33 % of the DNA sequences was deemed unusual; only 60 % (or less) of the DNA was related to known gene sequences. The extent of this difference might be enough to exclude these organisms from the known domains of life.
The authors conclude that their findings indicate the possibility that “major divisions of life have yet to be discovered”.
Now, scientists will have to analyse these organisms further to determine whether they really are from another domain.
Meanwhile, we, laymen, have no choice but to wait to find out about the true nature of these organisms.