Excerpt: “The findings also provide a framework for understanding fascinating evolutionary questions, such as why humans of different ethnicities have distinct facial features and how these are embedded in our genome. IRX genes have been repeatedly co-opted during evolution, and small variation in their activity could underlie fine alterations in the way we look…”
This “Nature Genetics” paper (subscription required) details the complex stochiometry (i.e., ‘chemistry’) of intracellular signaling and stochastic gene expression. A link from one nutrient chemical (folate) to genetically predisposed gonadal and craniofacial effects brings to bear the interdisciplinary approach that is required to link epigenetic effects, nutrient chemicals, pheromones, intracellular signaling, gene expression, and transgenerational epigenetic inheritance to reproduction (or not) associated with the visual perception of physical (e.g., facial)features.
Evolutionary theorists and sexuality researchers may want to reconsider how much they know about the genetically predisposed nutrient-dependent visual appeal of human facial characteristics and try to explain how a random mutation or anything except nutrient chemicals could cause adaptive evolution that is manifested in the physical features and pheromones of species from microbes to man. Faces and brains do not seem to be required for adaptive evolution. Nutrient chemical and pheromones are required.
The basic principles of biology and levels of biological organization continue to show that the visual appeal of conspecifics in species with eyes and brains is a conditioned response to olfactory / pheromonal input. The same basic principles of biology and levels of biological organization are unquestionably responsible for the visual appeal of food in species with eyes and brains. Is there another model for that?
If not, human pheromones must be responsible for the visual appeal of other people, as detailed in: Human pheromones and food odors: epigenetic influences on the socioaffective nature of evolved behaviors