Objective/context: The European Enlightenment debates on the influence of climate over a region’s inhabitants created a gendered discourse that questioned the virility of European men born and raised in the Americas, while at the same time reducing American indigenous men to a state of infancy. These scientific discussions, which circulated throughout the American continent, had a particular resonance in Lima’s Enlightenment newspaper the Mercurio Peruano. This was due to the broader discussion on the sources of effeminacy and feebleness among Limeño men of which this scientific debate was a part. Originality: This article explores the gendered dimension of European and American scientific discussions on climatic determinism, researching a particular case: the knowledge produced by the contributors to the Mercurio Peruano (mercuristas), dismissing European misrepresentations that claimed Peruvian men lacked virile features. Methodology: Looking primarily at natural history produced in Europe, the reactions in the Peruvian Enlightenment press, but also public debate and further knowledge produced in Peru, this research analyzes scientific discourses from a gender perspective centered on masculinities. Conclusions: Based on Connell’s masculinity theory, this article demonstrates that the extensive scientific knowledge produced by the Mercurio Peruano, praising the benefits of the land for Peruvian manhood, promoted a new form of industrious fatherhood-centered masculinity.