Darwin thought that the moral sense was among the most challenging aspects of human life to account for through evolutionary explanations. This article seeks to probe the question about human uniqueness primarily from a theological perspective by focusing in depth on one distinctive moral sentiment, gratitude, particularly in the thought of Thomas Aquinas. It uses that example as a case study about how to consider the validity of arguments for human uniqueness within the broader compass of the cultural evolution of (...) sociality and morality within the human sciences, including evolutionary anthropology. Further questions about the evolution of religion surface in this discussion since gratitude, from a theological perspective, necessarily includes gratitude to God as a fundamental aspect of religious faith and practice. (shrink)