The gut microbiota consists of trillions of microbes and is crucial in health and disease in vertebrates, including humans and other primates. Eggerthellaceae, a bacterial family in the mammalian gut microbiome, is important in various specialized metabolic processes. Although this family is common in mammals, their roles in non-human primates (NHPs) remain largely unexplored. This study investigates how Eggerthellaceae metabolic functions vary across primate hosts, focusing on conserved core metabolic pathways and specialized genes involved in flavonoid and lignan metabolism. We analyzed 12 high-quality Eggerthellaceae metagenome-assembled genomes (MAGs) from the gut microbiomes of 5 NHP species. We annotated metabolic functions using DRAM, RAST-tk, metabolic modeling, and BLAST, comparing the results to the common human gut microbe Eggerthella lenta. Our preliminary results reveal that Eggerthellaceae in NHPs share many but not all metabolic traits. For example, amino acid transporter profiles differ between NHP strains. Senegalimassilia, a genus in primate gut microbiota, exhibits more similarity to human-associated strains than other genera. Additionally, none of the NHP genomes contain genes similar to the ber lignan reductase in Eggerthella lenta. Our ongoing work includes identifying additional genes involved in polyphenol metabolism and investigating the potential coevolution between Eggerthellaceae and NHPs. These efforts aim to deepen our understanding of how host phylogeny and dietary adaptations influence the metabolic functions of Eggerthellaceae in primate gut health. This variability could provide new insights into the evolution of gut microbiota and how its functional roles differ between humans and NHPs.