Any study that indicates no olfactory bulb neurogenesis occurs in adult humans argues against the design in biology that ensures the plasticity of our brain-directed behavioral response to novel stimuli in our environment…
The direct effect of food odors and social odors on signalling pathways makes the epigenetic effects of chemical cues as important to the understanding of human behavior as they are to the understanding of behavior in every other species. This is especially true for placental mammals.
…model organisms make clear the extension of the concept to nutrient chemical and pheromone-dependent neurogenic niches, human brain development, and individual differences in behavior.
1) ecology and the nutrient chemical-dependent evolution of ecological niches;
2) social interactions and the pheromone-dependent evolution of social niches.