A gene selection analysis of TAS1R1 and TAS1R3 to examine human carnivory

Humans are considered to have a unique reliance on meat compared to other primates, as much of humans unique evolutionary trajectory, such as human brain expansion, is linked to the increased consumption of meat for calories and nutrients. However, other primates such as chimpanzees (Pan troglodytes) and bonobos (Pan paniscus) are also known to consume meat. While humans meat consumption is considered to be unique in humans increased incorporation of tools to process the prey carcass and consumption of a broader range of prey, these distinctions are less obvious when contextualized within the broader behavioral repertoire of Pan species carnivory. This research seeks to identify if the taste perception of meat is different between humans and other ape clades through gene selection analyses. Specifically, this work examines the umami taste receptor genes, TAS1R1 and TAS1R3, which enable the savory flavor perceived when eating meat. Using PAML, we test for positive selection in these genes across several ape clades. We infer positive selection in TAS1R1 for the homininae clade and positive selection in TAS1R3 for the Homo/Pan clade. No selection was detected in only the human lineage, which complicates claims that human carnivory is unique compared to other primates while simultaneously suggesting the role of meat may be unappreciated in chimpanzees and bonobos as well as the role of insectivory in gorillas.