Man, his dog and their microbes
We share many of the microbes that live on our skin and in our body with the people (and pets) we live with.
The human body is home to many different microbes, with a range of bacteria, fungi and archaea living on the skin, in the intestine and at various other sites in the body. While many of these microbes are beneficial to their human hosts, we know very little about most of them.
Early research focused primarily on comparing the microbes found in healthy individuals with those found in individuals suffering from a particular illness. More recently researchers have become interested in more general issues, such as understanding how these collections of microbes, which are also known as the human microbiota or the human microbiome, become established, and exploring the causes of similarities and differences between the microbiota of individuals.
We now know that the communities of microbes found in the intestines of genetically related people tend to be more similar than those of people who are not related. Moreover, the communities of microbes found in the intestines of non-related adults living in the same household are more similar than those of unrelated adults living in different households. We also know that the range of microbes found in the intestine changes dramatically between birth and the age of 3 years. However, these studies have focused on the intestine, and little is known about the effect of relatedness, cohabitation and age on the microbiota at other body sites.
Se Jin Song and colleagues compared the microbes found on the skin, on the tongue and in the intestines of 159 people — and 36 dogs — in 60 families. They found that co-habitation resulted in the communities of microbes being more similar to each other, with those on the skin being the most similar. This was true for all comparisons, including human pairs, dog pairs and human–dog pairs. This suggests that humans probably acquire many of the microbes on their skin through direct contact with their surroundings, and that humans tend to share more microbes with individuals, including their pets, with which they are in frequent contact.
Song and colleagues also discovered that, unlike what happens in the intestine, the microbial communities on the skin and tongue of infants and children were relatively similar to those of adults. Overall, these findings suggest that the communities of microbes found in the intestine changes with age in a way that differs significantly from those found on the skin and tongue.
To find out more
Read the eLife research paper on which this story is based: “Cohabiting family members share microbiota with one another and with their dogs” (April 16, 2013).
eLife is an open-access journal that publishes outstanding research in the life sciences and biomedicine.
