Relationships are complicated, even in nature. Two unrelated species living close together and interacting for survival is called symbiosis. There are three types of symbiotic relationships: mutualism, commensalism, and parasitism.

In a mutualistic relationship, both organisms benefit from the interaction. One example is the relationship between honeybees and flowers. Honeybees drink nectar from flowers, collecting and carrying pollen as they fly from one flower to another. Nectar allows bees to make honey, and spreading pollen helps flowers reproduce. Another example of a mutualistic relationship is between clownfish and sea anemones. The sea anemone provides protection and shelter, while clownfish waste provides the sea anemone with nutrients.

Have you ever noticed a skin care product advertised as “microbiome friendly” and wondered what that meant? The microbiome is the collection of all the microbes—including bacteria, viruses, and fungi—that live in a specific environment, such as on the skin or in the digestive tract.

It’s a common misconception that all microbes are harmful—in truth, much of the human microbiome is made up of microbes that form beneficial symbiotic relationships with us. Microbiome-friendly skin care products don’t have antimicrobial properties that could harm the beneficial bacteria that live on our skin.

Your Microbiome and You

Cataloging the human microbiome—the complete collection of bacteria, fungi, archaea, protists, and viruses that live in and on our bodies—is an enormous task. Most estimates put the number of organisms who call us home on par with the number of our own cells. Imagine trying to figure out how the billions of critters influence each other and, ultimately, impact our health. Elhanan Borenstein, a computer scientist-cum-genomicist at the University of Washington, and his team are not only tackling this difficult challenge, they are also trying to obtain a systems-level understanding of the collective effect of all of the genes, proteins, and metabolites produced by the numerous species within the microbiome.

You’ve likely heard some variation of the statistic that there are at least as many microbial cells in our body as human cells. You may have also heard that the microscopic bugs that live in our guts, on our skins, and every crevice they can find, collectively referred to as the human microbiome, are implicated in human health. But do these bacteria, fungi, archaea, protists, and viruses cause disease, or are the specific populations of microbes inside us a result of our state of health? That’s the question that drives the research in the lab of Andrew Goodman, associate professor of microbial pathogenesis at Yale University.