International Society of Human Ethology, August 1-5, 2010, Madison, Wisconsin
J. V. Kohl
Human Pheromones: Linking Neuroendocrinology and Ethology (revisited)
The evolution of food choice and mate choice provides a bottom-up model that reveals we are genetically predisposed to respond to olfactory/pheromonal input with alterations that occur in hormone-secreting cells of tissue in the brain. With unparalleled reciprocity, the development of human personal preferences for visually perceived physical features is accompanied by a top-down model. The direct effect of the olfactory/pheromonal input on the central nervous system alters the genetically predisposed maturation of the neuroendocrine system and the reproductive system during a behavioral maturation sequence driven by the same hormone-secreting nerve cells. This direct effect of olfactory/pheromonal input is associated with other sensory input from the social environment that is not required for the development of human personal preferences (e.g., visual input associated with visually perceived physical features). Cultural effects on behavior are effects of gene-culture co-evolution that allows us to think about the relative salience of sensory input.
Visual input from our social environment co-exists in reports of observed behavioral affects that tend to confuse co-existence with cause and effect. This confusion arises from the failure to incorporate evidence of an evolved neurophysiological mechanism that directly links what we see to changes in hormones that affect our social behavior. The failure to mention this required neurophysiological mechanism is exemplified in reports that link visual stimuli to co-existing personal preferences for the physical features of others. Human personal preferences for these physical features are most often linked to visual input in the absence of any mammalian model for their development.
Any evolved link to mammalian behavior from a sensory stimulus in the social environment must incorporate five levels of biological organization that allow the link to evolve: 1. gene; 2. cell; 3. tissue; 4. organ; 5. organ system. During embryonic and prenatal development of the mammalian central nervous system (CNS), genes in cells of tissue in the brain (i.e., the most important organ of any organ system associated with the development of behavior) predispose the ability of hypothalamic tissue to generate the pulsatile secretion of gonadotropin releasing hormone (GnRH). The hypothalamic GnRH pulse modulates the concurrent maturation of the reproductive system, the neuroendocrine system, and the CNS during behavioral development.
It is generally agreed that the social behavior of many other animals is affected most by olfactory/pheromonal input, which acts on GnRH pulsatility. A mammalian model details how olfactory/pheromonal input alters genes in cells of tissue in the brain. This bottom-up gene-cell–tissue-organ-organ system model has its evolutionary basis in animal models of food choice and mate choice, both of which are required for survival of all species that sexually reproduce. With unparalleled reciprocity, the development of human personal preferences for visually perceived physical features is accompanied by a top-down explanation. The direct effect of the olfactory/pheromonal input on the CNS alters the genetically predisposed maturation of the neuroendocrine system and the reproductive system during the behavioral maturation sequence that is driven by the hormone-secreting (i.e., GnRH) nerve cells.
This genetically predisposed behavioral maturation sequence incorporates evolutionary aspects of self/non-self recognition (immune system function) and evolutionary aspects of sex differences and their recognition. Cultural effects on behavior are attributed to gene-culture co-evolution, rather than to any vague means by which culture might otherwise influence behavior.