Intestinal bacteria may have at least 15 million years

Certain intestinal bacteria arose at least 15 million years, long before humans, according to a survey published on Thursday.

This finding suggests that evolution has a major role in the composition of intestinal macrobiotic than previously thought, according to the researchers, whose work was published in the American journal Science.

These bacteria contribute to the early stages of development of our intestines, train our immune system to fight pathogens agent, and can even affect our mood and behavior, the study indicates.

When humans and apes evolved into different species from a common ancestor, the bacteria present in the intestines of the latter have also evolved in different lineages, the researchers said.

Thus, the first differentiation of intestinal bacteria occurred about 15.6 million years ago, when the line of gorillas diverged from the hominid.

The second was 5.3 million years ago, when the human branch is separated from chimpanzees.

"We knew for some time that humans and our closest cousins, the great apes, have these bacteria in their intestines," says Andrew Moeller, a researcher at the University of Berkeley and co-author of the study.

"The big question we wanted to answer was where they came from these bacteria, if our environment or our evolution, and how long the lines were kept," he adds.

To conduct their research, the scientists analyzed fecal samples from chimpanzees, bonobos and gorillas living in the wild in Africa, and people in the United States.

Fossils and genetic indexes allowed to establish that these four hominid species evolved from a common ancestor that lived more than 10 million years ago.