“Babies learn mum’s unique odour.” October 4th, 2012.
Excerpt: “This is a neat study which shows the value of studying the development underlying an apparently ‘innate’ behavior.” Dr Tristram Wyatt of the University of Oxford. “The surprising result is that mouse pups use the individual odours of the mother to find their first feed.”
My comment: In Kohl (2012) I wrote: “It is now clearer how an environmental drive probably evolved from that of food ingestion in unicellular organisms to that of socialization in insects. It is also clear that, in mammals, food odors and pheromones cause changes in hormones such as LH, which has developmental affects on sexual behavior in nutrient-dependent, reproductively fit individuals across species of vertebrates.”
What surprises me is that Dr Wyatt seems not to be aware that mouse pups, like all infant mammals, find food when they locate the nutrient-dependent pheromones of the mother.
Darren W Logan, Lisa J Brunet, William R Webb, Tyler Cutforth, John Ngai, Lisa Stowers. (2012) ‘Learned recognition of maternal signature odors mediates the first suckling episode in mice‘ Published in Current Biology, 4 October 2012.
Excerpt: “Here we use behavioral analysis, metabolomics, and calcium imaging of primary sensory neurons and find no evidence of ligands with intrinsic bioactivity, such as pheromones, acting to promote first suckling in the mouse. Instead, we find that the initiation of suckling is dependent on variable blends of maternal “signature odors” that are learned and recognized prior to first suckling.”
My comment: I use the term olfactory/pheromonal input in an attempt to clarify that the epigenetic effects of nutrient chemicals and pheromones cause the required changes in intracellular signaling and stochastic gene expression enables nutrient chemical-dependent changes in pheromones. The pheromones effect hormones that affect social behavior, which is essential to the development of sexual behavior. The attempt to change the concept of olfactory/pheromonal communication to one where “signature odors” somehow affect behavior seems rather pointless. There is no mention of how the “signature odors” could cause the epigenetic effects that are required for adaptive evolution, which I have modeled in Kohl (2012).
Next month I will present the latest graphic illustration of the diagram I have been presenting since 1992. Here is the abstract from that forthcoming presentation.
Human Pheromones: Epigenetic effects of odors and their affects on behavior
Background: Integrated chemical ecology supports a model for adaptive evolution of human sexual behavior via ecological, social, neurogenic, and socio-cognitive niche construction. The model details the epigenetic effects of 1) nutrient chemicals on reproductive fitness and 2) reproduction controlled by pheromones.
Theoretical Perspective: In mammals, olfactory/pheromonal input activates gene expression, and changes in hypothalamic gonadotropin releasing hormone (GnRH) secretion. Changes in GnRH secretion are evidenced in downstream effects on other hormone secretion throughout the hypothalamic-pituitary-gonadal (HPG) axis and hypothalamic-pituitary-adrenal (HPA) axis. Food odors and pheromones activate the prenatal organization of the HPG and HPA axes and postnatally “calibrate” the genetically predisposed survival potential of individuals and of species. Calibration of odor preferences occurs via effects on synaptogenesis, synaptolysis, and apoptosis throughout life. In mammals, these effects of odors are routinely associated with neurotransmission, hippocampal neurogenesis, learning, and memory during classically conditioned hormone-driven changes in behavior. In people, these epigenetic effects of odors are typically consciously associated only with input from spectral senses or tactile sensations.
Significance to the Field: Extension to people of the molecular biology common to all species explains how cerebral activation of hormone-secreting neurons and processes commonly attributed to individual components of the model, like genes or hormones, results in genetically predisposed phenotypic expression, which may or may not be physically or behaviorally manifested during development. The explanation includes 1) a cognitive component associated with the identification and categorization of some odors; 2) an emotional component associated with odors and increased or decreased arousal, appetite, and satiation; 3) a motivational component linked to processes that direct behavior toward or away from food odors and pheromones; and 4) a neurophysiological component, directly linked from odors to gene activation in hormone-secreting nerve cells of brain tissue; to HPG / HPA axis variability, socio-cognitive niche construction and to behavioral development.