This study focuses on the impact that urbanization and human interactions have on the gut microbiome of wildlife. These animals that come into contact with humans have shown that they have differences in their microbiome, rather than other animals of the same species that are deep in the woods with no human contact. The process of animal microbiomes becoming more like people’s is called “humanization” of their microbiome. This is a very important factor when studying human-animal interactions in urban areas, because these distinct changes are indicators of urbanization.

The research performed in this study was done on 3 different animals: anoles, coyotes, and sparrows. These animals were tested in both urban and rural areas around the world. Some samples were taken from Puerto Rico, some were from California, and others, like Venezuela or Cameroon. The diversity of the animals and places reduced the amount of bias and error that the results would show. The more diverse the location and the species of animal, the more reliable the data. To compare the animal microbiota findings, the researchers compared these microbes to humans. The more similar they were to humans, the more humanization that occurred in the animal’s microbiome.

The results of the research showed that the closer an animal lives to an urban area, the more their microbiome reflects humans. The closer animals were to humans, the more human-associated bacteria there were in their gut. This clear shift in microbiome contents between wildlife coming into contact with urban areas/cities versus wildlife that lives in the wild indicates a clear humanization of microbiomes in animals.

Some changes or improvements that I would make for next time would be to look into more of the causes of why humanization occurs, rather than focus on whether or not it occurs. With this research, we know that it does happen, but I think it would be of better use to know where it stems from. For example, do animals that eat human trash have an increased number of human-associated microbes? Is that the number one cause of humanization of animal microbiomes? If not, then what is? Though it is important to know that humanization of microbes exists, I think the next area of research needs to focus on how animals are at an increased risk of exposure to human microbes, as well as how that impacts them.

Citation: Dillard, B. A., Chung, A. K., Gunderson, A. R., Campbell-Staton, S. C., & Moeller, A. H. (2022). Humanization of wildlife gut microbiota in urban environments. eLife, 11, e76381. https://doi.org/10.7554/eLife.76381