Social interactions among gut microbes shape our lives

hen it comes to the gut, it’s not which microbes you have but how they interact that appears to affect health.

This insight comes from a recent study of fruit fly gut microbes that explored the puzzling results of a UC Berkeley study from 91 years ago. Conducted in 1927 by Helen Steinfeld for her Ph.D. dissertation in zoology, her experiment demonstrated that by simply removing the gut bacteria from fruit flies, she could extend their lifespans by 14 percent.

Will Ludington, a former UC Berkeley Bowes Fellow now at the Carnegie Institution for Science in Baltimore, MD, confirmed Steinfeld’s results but carried the experiment much further, adding back different combinations of five bacterial species to see how interactions among them affected the flies’ health, in particular lifespan and fertility.

He and his team found that the interactions that take place among the microbial populations are as important to the fly’s physiology as which individual species are present. While removing all microbes increased a fly’s lifespan by 23 percent, adding back any one of the species could account for only one-quarter of this effect. Interactions among the five separate species accounted for the rest.

“The classic way we think about bacterial species is in a black-and-white context as agents of disease — either you have it or you don’t,” Ludington said. “Our work shows that isn’t the case for the microbiome. The effects of a particular species depend on the context of which other species are also present.”

Moreover, flies with a more diverse gut community had more offspring, even though they lived shorter lives. The longer-lived flies with sterile guts had fewer offspring.

“As we examined the total of what we call a fly’s fitness — its chances of surviving and creating offspring — we found that there was a tradeoff between having a short lifespan with lots of offspring, versus having a long lifespan with few offspring,” Ludington explained. “This tradeoff was mediated by microbiome interactions.”

The experiment required development of a novel system for mapping all the possible interactions between the five species of bacteria found in the fly gut in order to see how they affected an insect’s development, production of offspring and lifespan, which are a measure of its fitness. The analysis of the interactions also required developing new mathematical approaches.

Though the fruit fly gut is much simpler than that of humans, the results mean “that if we want to understand how the microbiome impacts our health, we need to develop a predictive understanding of how combinations of bacteria affect the host, not just the individual species,” he added.

Ludington and his team, including molecular biologists Alison Gould, Vivian Zhang and Benjamin Obadia of UC Berkeley, physicists Eric Jones and Jean Carlson of UC Santa Barbara, mathematicians Lisa Lamberti, Nikolaos Korasidis and Niko Beerenwinkel of ETH Zurich and Alex Gavryushkin of the University of Otago, published their findings online last month in the Proceedings of the National Academy of Sciences.


  1. All social interactions are food energy-dependent and biophysically constrained by the pheromone-controlled physiology of reproduction in species from microbes to humans.

    The first indication of that fact appeared in 1855 as “On the Influence of the Human Instinct in the Prevention and Cure of Disease, Chiefly in Reference to Diet”

    Darwin addressed this in the context of his “conditions of life.” (1859-Chapters 4-6) Thomas Hunt Morgan won the Nobel Prize in Physiology or Medicine in 1933 for discoveries in flies that elucidated the role that chromosomes plays in heredity. In the same year, Erwin Schrodinger won the Nobel Prize in Physics.

    2017 Nobel Laureate, Ben Feringa put everything known to serious scientists about energy-dependent healthy longevity back into the context of the creation of sunlight and biblical prophesy. See: The Future of Chemistry – Schrödinger at 75: The Future of Biology

    “Disabled were walking again, the blind were seeing again, and the death rose from the grave. 2013 was the year in which prophesy from the bible became reality. — De Correspondent dec 2013”

    See also: Nutrient-dependent Pheromone-Controlled Ecological Adaptations: From Angstroms to Ecosystems

    If you do not realize that theorists from all disciplines have been lying to you about what is known, there are two games for ages 10+ that teach you how to link the creation of “Subatomic” particles from food energy to “Cytosis” and protection from the viruses that cause all diseases.


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