Humans have lost half primate ancestors' gut bacteria

A few days ago, I blogged here about certain deletions of genes in the human genome that made us human.

"In the study, researchers compared populations of gut bacteria found in chimpanzees and bonobos, our closest relatives, with those of humans – which in total amount to some 10,000 different lineages of bacteria. The scientists analyzed the evolutionary relationships of these bacteria in primates and identified groups of bacteria that were present in distant ancestors of humans and primates. Strikingly, the results showed that these ancestral symbionts are being lost rapidly from the human lineage. ..."

From the abstract:

"Humans and other primates harbour complex gut bacterial communities that influence health and disease, but the evolutionary histories of these symbioses remain unclear. This is partly due to limited information about the microbiota of ancestral primates. Here, using phylogenetic analyses of metagenome-assembled genomes (MAGs), we show that hundreds of gut bacterial clades diversified in parallel (that is, co-diversified) with primate species over millions of years, but that humans have experienced widespread losses of these ancestral symbionts. Analyses of 9,460 human and non-human primate MAGs, including newly generated MAGs from chimpanzees and bonobos, revealed significant co-diversification within ten gut bacterial phyla, including Firmicutes, Actinobacteriota and Bacteroidota. Strikingly, ~44% of the co-diversifying clades detected in African apes were absent from available metagenomic data from humans and ~54% were absent from industrialized human populations. In contrast, only ~3% of non-co-diversifying clades detected in African apes were absent from humans. Co-diversifying clades present in both humans and chimpanzees displayed consistent genomic signatures of natural selection between the two host species but differed in functional content from co-diversifying clades lost from humans, consistent with selection against certain functions. This study discovers host-species-specific bacterial symbionts that predate hominid diversification, many of which have undergone accelerated extinctions from human populations."

Humans have lost half primate ancestors' gut bacteria | Cornell Chronicle A new study finds that hundreds of bacterial groups have evolved in the guts of primate species over millions of years, but humans have lost close to half of these symbiotic bacteria.

Widespread extinctions of co-diversified primate gut bacterial symbionts from humans (no public access)