Lack of Heterogeneous Study Samples in Farm Animal Cognition Research

Farm animals have received limited attention in animal cognition research, despite their numbers and biomass surpassing all other mammalian species, including humans. Nevertheless, studying farm animal cognition can yield benefits for both fundamental and applied research. First, in a comparative context, cognitive research on farm animals and their wild counterparts can provide insights into how domestication has shaped the evolution of the brain, including our own. Second, in an applied context, understanding the cognitive processes of farm animals can improve our knowledge of how they perceive their environment and how their environment shapes their cognitive development, helping to inform better husbandry practices that meet their abilities and needs. To examine the characteristics of farm animal cognition studies, we conducted a scoping review of the cognition literature on cattle, pigs, sheep, and goats, focusing on potential biases in study samples. These species were well represented across different cognitive task types (learning, physical, social, and other), though learning tasks and pig studies were slightly overrepresented. Most studies were conducted on single breeds at single sites (which were most often research sites), with an overrepresentation of females and young animals (i.e., under one year), limiting the generalizability of findings and our interpretation of fully developed cognitive capacities in these species. Geographically, the majority of studies originated from North America or Europe, restricting international representation and limiting insights into local breeds across the globe. These sample biases reduce diversity, compromise generalizability, and can hinder broader understanding of farm animal cognition - knowledge that is crucial for understanding the impact of domestication on the brain and for improving husbandry practices to meet farm animals' perceptual and cognitive needs. We conclude by proposing strategies to achieve more diverse and representative study populations in farm animal cognition to mitigate the above-mentioned shortcomings.