Strepsirrhini
At the Duke Lemur Center, the researchers from the North Carolina State University examined three lemur species. Lemurs are Strepsirrhini, a suborder of primates; the three species used for this research were the leaf-eating Coquerel’s sifaka (Propithecus coquereli), the black-and-white-ruffed lemur (Varecia variegata) and the ring-tailed lemur (Lemur catta). The latter two have an identical fruit diet, but very different digestive tracts. The digestive system of the black-and-white-ruffed lemur is very simple – practically a straight line – while that of the ring-tailed lemur is far more complex with far more bends, just like a human one. The researchers gathered data on the diet of each species, after which they used genetic sequencing techniques to determine the bacterial composition of the gut microbiota. They also examined the chemical products produced by the gut bacteria.
Identical bacteria
All humans have a similar digestive tract, but their gut microbes depend strongly on their diet. Despite the great differences in the structure of their digestive tract, black-and-white-ruffed lemurs and ring-tailed lemurs apparently have a very similar gut microbiota. The researchers attribute this to the remarkable similarity of their diets. This study shows that, with similar diets, very different digestive systems can still have very similar gut bacteria.
Digestive problems in humans
However, the team of researchers made another remarkable discovery. ‘We wanted to know which microbes were present and what they were doing’, says Erin McKenney, lead author of the article on the NCSU website. ‘We found, among other things, some similarities between lemurs and humans – their distant primate cousins.’ Black-and-white-ruffed lemurs and ring-tailed lemurs had several metabolic pathways in common with humans with inflammatory bowel diseases, like Crohn’s disease. ‘In humans, it’s thought that these metabolic pathways may be contributing to intestinal health problems’, McKenney says. ‘But those same metabolic pathways in lemurs don’t appear to harm the animal’s health.’ This raises some interesting questions about the role of these metabolic pathways in humans. Are the relevant microbes actually harmful, or is there no causal relationship between metabolic pathways and digestive problems, despite the correlation? These are questions to which we do not yet have an answer.