CrAssphages are a type of bacteriophage, a virus that infects bacteria and reproduces within them. They are thought to infect one of the most prevalent bacteria in the human gut microbiome, Bacteroides (Dutilh et al., 2014). CrAssphages are suspected to be in 73-77% of humans (Siranosian et al., 2020), however little is known about the effects they might have on the gut microbiome or the host organism’s digestion, metabolism, nutrition, or host immune function and disease states (Shreiner et al., 2015). CrAssphages were recently identified in gelada fecal samples from infants and adults. This study analyzed variables surrounding crAssphage presence in fecal samples collected throughout infant development and from adults and analyzed the presence of six crAssphages that were genetically similar to the proto-crAssphage originally discovered in humans (Dutilh et al., 2014). It was determined that recent rainfall has a significant effect on crAssphage presence. Additionally, recent rainfall and gelada sex have significant effects on the likelihood of infection by multiple crAssphages at once. The six crAssphages analyzed all peaked in presence between 10-20 months of age, while Bacteroides presence decreases at ~10 months (Baniel et al., 2022). It remains unsure if Bacteroides are the true host of crAssphages, or if there are other possible hosts.