Study examines primate’s guts

New research shows that evolution trumps environment.

A study led by Dr. Howard Ochman, Yale Ecology and Evolutionary Biology professor, revealed that bacteria found in the guts of primates may not be a result of what they eat, but rather a result of heritage. The paper, titled “Evolutionary Relationships of Wild Hominids Recapitulated by Gut Microbial Communities,” was published on Nov. 16 in the journal PLoS Biology and investigated differences in the types of bacteria found in the stomachs and intestines of primates. Genetics professors said the research will help build understanding of the evolutionary links between species.

“The composition of the community of gut microbes in humans and our closest relatives maps onto the evolutionary tree just like any other trait, rather than being determined only by the environment,” said Dr. Michael Worobey, a University of Arizona associate ecology and evolutionary biology professor and co-author of the present study.

Researchers extracted DNA from the feces of five primates, humans, chimpanzees, bonobos, and Western and Eastern Lowland Gorillas. After analyzing the fecal material, they investigated the relationships between the DNA in the fecal matter, to see whether there were any variations in the bacteria, which help the uptake of nutrients in the intestines.

“We showed that phylogeny, or the relationships of the host, plays a dominant role in the diversification of gut communities in great apes,” Ochman said.

Gut microbes are miniscule digesting machines that number in the trillions and live in stomachs and intestines and play a vital role in metabolic processes.

Ochman said that these bacteria are also important in health and disease.

“The community that [the bacteria] form is easily as important to our biology as many of our organs, providing vitamins, protection from disease, even affecting obesity,” Worobey said. “It’s like each one of has a tiny ranch inside of us, with trillions of domesticated bacteria providing biochemical goods.”

Ochman decided to study gut bacteria in primates as a key to understanding gut bacteria in humans, he said, adding that studying gut bacteria in great apes can inform us about its contents, evolution and function.

Dr. Irene Eckstrand, program director at the National Institute of General Medical Sciences department of the National Institute of Health, decided to fund this work because increased knowledge of how humans and primates acquire microbial communities allows scientists to better understand the basis of health and disease, she said.

Eckstrand said she finds Ochman’s research compelling because it shows how gut microbial communities can be used as phylogenetic markers, helping scientists understand evolutionary relationships between species.

Genetics professor Dr. Kenneth Kidd said this study provides a clear baseline for understanding bacterial variation.

Kidd added the study is significant in uncovering evolutionary ties between species.

“Communities of gut flora are clearly important to human health overall and deserve greater understanding,” he said.

Chimpanzees and humans share approximately 98.4 percent of their genes, according to Jared Diamond, author of the book “The Third Chimpanzee.”

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