Smelling the difference between young and old

Informative Body Odor

By Edyta Zielinska

Humans can tell the difference between the body smells of the young and the old, and find that youth is smellier.

The Smell of Age: Perception and Discrimination of Body Odors of Different Ages

My comment:

Nutrient chemicals in the ecological niche calibrate individual survival, and the nutrient chemicals metabolize to pheromones in the social niche, which standardize and control reproduction in all species. Ecological and social niche construction also are required for adaptive evolution. For example, the construction of ecological and social niches results in epigenetic effects of food odors and pheromones on the hypothalamic neurogenic niche responsible for mammalian brain development and behavior. This exemplifies the design that is apparent in biology. That is, the transgenerational epigenetic inheritance of the molecular mechanisms for food preferences and social/kin preferences are manifestations of the common molecular biology of organisms from microbes to man.

Given the fact that body odors (social odors called pheromones) convey social cues that are as important as food odors to species survival in all species, it should surprise no one that we can detect differences in age via these olfactory/pheromonal cues. How could this not be the same in humans as in every other species that can detect the differences in aged foods and aged conspecifics. Food odors and pheromones classically condition our response to the visual appeal of food and conspecifics as occurs in all other animals. It’s nice to see the data that prove another aspect of this model for species survival, but to many people it’s common sense. Isn’t it? You’re not likely to eat something that doesn’t smell right, or mate with anyone who doesn’t smell right. The common sense that ensures that is olfaction.

A thought experiment

I may be confused about proximate and ultimate cause, especially if the role of transgenerational epigenetic inheritance is not central to the extended evolutionary synthesis. Isn’t transgenerational epigenetic inheritance the problem that led Dickins and Rahman to suggest a thought experiment; one where epigenetic mechanisms introduce shifts in learning bias for certain associations as would endocrine functioning? If so, my model (Kohl, 2012), which combines the epigenetic effects of nutrient chemicals and pheromones with biased endocrine functioning and adaptive evolution, may help move the modern synthesis forward.

I tried this before, but the evolutionary continuum from microbes to man (Kohl, 2007) seems too much to grasp in the context of biased endocrine functioning. However, the honeybee has since emerged as a model organism to exemplify nutrient chemical and pheromone-dependent epigenetic alterations in endocrine functioning. These epigenetic effects that bias endocrine functioning are required for the adaptive evolution of reproduction.

Reproduction is required for transgenerational epigenetic inheritance and species diversity, which is perhaps better represented in the threespine stickleback vertebrate model organism. However, in all invertebrate and vertebrate model organisms, nutrient chemicals establish the ecological niche of individuals, and the presence of conspecifics establishes their social niche (as also occurs with microbial species).

The honeybee best exemplifies how  ecological and social niches contribute to the hypothalamic gonadotropin releasing hormone (GnRH) neurogenic niche that is responsible for the adaptive evolution of the human brain. Simply put, what the queen eats determines her pheromone production and everything else about the social interactions in the colony, including the required epigenetic effects of pheromones on the neuroanatomy of the worker bee’s brains during the development of their diverse behaviors that change with exposure to different chemical input associated with a variety of other sensory input of lesser importance / salience.

Of course, that sounds too simple in the context of the extended evolutionary synthesis and human brain evolution. But the molecular biology is conserved across species, which is helpful for proof of concept. In placental mammals, for example, in utero nutrient chemical transfer is responsible for organization of the brain’s postnatal activation by nutrient chemicals and pheromones. The proper GnRH-driven behavioral response of the infant to activation by these chemicals ensures its survival, just as the proper response of the honeybee worker bee’s brain to nutrient chemicals and pheromones ensures its survival and helps to ensure the colony’s survival via changes in the neuroanatomy of its brain. (Parenthetically, spectral input may or may not be correlated with direct epigenetic effects on the brain, but it is not causal to brain development.)

Model organisms have their molecular biology in common with all other organisms. No organism survives in the absence of sufficient nutrient chemicals. Ecological niches contract. And no species survives in the absence of reproduction controlled by pheromones. I think that’s why we are now seeing more reports on transgenerational epigenetic inheritance, with causal links to speciation via ecological and social niches in all species. We should soon see the addition of neurogenic niches in many others.

What I don’t see is anyone who is integrating the ecological, social, and neurogenic niches and considering the epigenetic effects of nutrient chemicals and pheromones in the context of endocrine disruption and transgenerational epigenetic inheritance. Nutrient chemicals and pheromones promote homeostasis and also allow adaptive evolution, including adaptive evolution of the human brain. Endocrine disruption causes atypical development of the brain and the body.

Isn’t that the apparent design we might all someday see in biology? Isn’t seeing the apparent design required to move forward from the Modern Synthesis to the Extended Evolutionary Synthesis?

Jim Kohl
www.pheromones.com

On 5/27/2012 3:26 AM, R.J.King@lse.ac.uk wrote:

jvkohl:
I fear that you may have confused proximate and ultimate. Easily done. Epigenetics, while fascinating, has no impact on the central doctine of genes as the sole information carriers. Epigenetics are just one more set of mechanisms by which genes achieve their ultimate aim of replication. I.e. they are part of the suite of adaptations. The University of Utah has an excellent site detailing this

http://learn.genetics.utah.edu/

May I particularly recommened this page which beautifully illustrates the way in which behaviours and epigenetics intereact in this way to calibrate personality to environment?

http://learn.genetics.utah.edu/content/epigenetics/rats/

My suspicion  is that the folk biology concept of "biology=fixed at birth" dies very very hard and keeps recurring in odd forms in even the best and brightest of us.

A nutrient chemical and pheromone-dependent neurogenic niche

The article linked below offers the first evidence I have seen for a diet-responsive neuogenic niche.

“Weight struggles? Blame new neurons in your hypothalamus.” May 21st, 2012.

Excerpt: “People typically think growing new neurons in the brain is a good thing – but it’s really just another way for the brain to modify behavior,” Blackshaw explains. He adds that hypothalamic neurogenesis is probably a mechanism that evolved to help wild animals survive and helped our ancestors do the same in the past.”

My comment:

In my model nutrient chemicals and pheromones have direct effects on hypothalamic neurogenesis, olfactory bulb neurogenesis, and hippocampal neurogenesis. These direct effects link nutrient chemicals and pheromones to the biological core of mammalian reproduction: the hypothalamic gonadotropin releasing hormone (GnRH) pulse.

In mammals, for example, food odors and pheromones cause changes in GnRH pulse frequency that result in patterns of neurogenesis responsible for the development of behaviors associated with proper food choice (individual survival) and proper mate choice (species survival). Food odors up-regulate and social odors down-regulate the calibration of stochastic gene expression responsible for control of speciation via hippocampal neurogenesis and the required learning and memory of species specific behaviors.

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.

The in utero and postnatal effect of the chemical stimuli is on the development of the hypothalamic GnRH neuronal niche, which is responsible for the conditioning of food preferences and mate preferences and the transgenerational epigenetic inheritance of all behaviors required for individual and species survival.  GnRH-dependent luteinizing hormone (LH) secretion, for example, is the link between proper nutrition and reproductive sexual behavior. The feedback loops are detailed in my model for the adaptive evolution of the human brain and behavior.

Kohl, J.V. (2012) Human pheromones and food odors: epigenetic influences on the socioaffective nature of evolved behaviors. Socioaffective Neuroscience & Psychology, 2: 17338.

Human pheromones: Olfaction, odor receptors, learning, memory, mood, brains and behavior

Learning and memory: The role of neo-neurons revealed

Excerpt: Beyond simply discovering the functional contribution of these neo-neurons, the study has also reaffirmed the clear link between “mood” (defined here by a specific pattern of stimulation) and cerebral activity. It has been shown that curiosity, attentiveness and pleasure all promote the formation of neo-neurons and consequently the acquisition of new cognitive abilities.

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My comment: The mouse model is one in which olfaction and odor receptors clearly link the role of nutrient chemicals in ecological niches that calibrate intracellular signaling and the development of social niches, which are standardized and controlled by pheromones that control species specific behaviors. Because the molecular biology is the same across species with or without eyes or a central nervous system, olfaction and odor receptors provide a clear evolutionary trail that can be followed from unicellular organisms to insects to other mammals and humans.

The idea that ecological niches and social niches are the determinants of neurogenic niches, like those that develop with exposure to food odors and social odors, is one that is important to consider whether we intend to look at pharmacogenomics or to better understand the development of human behavior in the context of epigenetic effects of odors on brain development. The role of odors and neo-neurons is one that can be examined in a model of adaptive evolution and behavioral development. These results attest to the fact that my model is the right one.

Brain Activation Areas of Sexual Arousal with Olfactory Stimulation in Men

Brain Activation Areas of Sexual Arousal with Olfactory Stimulation in Men: A Preliminary Study Using Functional MRI

Human studies of brain activation:

Excerpt 1: “The brain areas activated in the present study showed some areas of similarity compared with those identified in studies of visual sexual stimulation.”

Use of fragrance for human brain activation

Excerpt 2: “In this study, we used Chanel N°5 perfume (Chanel, Paris, France) as the medium for sexual arousal in male subjects.”

Animal studies of brain activation and behavior:

Excerpt 3: “In animal studies… the median preoptic area (MPOA) of the hypothalamus, and the limbic system have been shown to be essential for sexual motivation and performance [13]. McKenna [14] suggested that neurons within the MPOA, paraventricular nucleus of the hypothalamus, and the medial amygdala interact in a complex way to regulate sexual behavior in both men and women. The paralimbic areas, which consist of the inferior frontal lobe, corpus callosum, cingulate gyrus, parahippocampal gyrus, and uncus, are responsible for initiation, motivation, and goal-directed behaviors [12].”

My comment on the three excerpts from this article on brain activation:

Neurons within the MPOA are most likely to be collectively responsible for variations in the secretion of hypothalamic gonadotropin releasing hormone (GnRH). The role of GnRH in human sexual behavior was first detailed in a 1991 book chapter (Moss, Dudley, & Riskind, 1991).

A recent report links the likelihood of a diet-responsive hypothalamic neurogenic niche (Lee et al., 2012) to the postnatal differentiation of neuronal systems that interact with the ability of the MPOA to produce alterations in GnRH pulse frequency and amplitude in response to environmental influences (Forni, Fornaro, Guenette, & Wray, 2011). This diet-responsive hypothalamic neurogenic niche links the epigenetic effects of nutrient chemicals on GnRH to the evolution of the brain across species from microbes to man. Many other works link the epigenetic effects of pheromones to this diet-responsive neurogenic niche and to adaptive evolution of the human brain.

In mammals, GnRH pulse frequency and amplitude cause changes in the secretion of luteinizing hormone (LH). Nutrient chemicals associated with food acquisition and pheromones associated with conspecifics directly link changes in GnRH and LH from this hypothetical neurogenic niche to brain development and behaviors required for species survival in species from invertebrates to vertebrates. This direct link, via epigenetic effects on intracellular signaling that cause changes in stochastic gene expression that are linked via c-fos to GnRH (Kohl, 2012).

There is no direct link from visual or auditory stimuli that would explain any likelihood that spectral stimuli could classically condition the response to nutrient chemical associated with food odors. There is no direct link from spectral stimuli that supports the idea that spectral stimuli classically condition sex differences in responses to pheromones. The lack of the direct link from food odors and pheromones to classical conditioning of the LH response to spectral stimuli, like erotic imagery, leads to the conclusion that the response to erotic imagery is classically conditioned by olfactory/pheromonal input in precisely the same way that food odors classically condition the hormone responses associated with the visual appeal of food in men and women. Pheromones, however, are sexually dimorphic, which is why men and women respond to them differently, just as they respond differently to fragrances like the Chanel N°5 perfume (Chanel, Paris, France) used in the experiment I have just reported.

Bickering theorists: opinions about selfish genes and group selection

The Descent of Edward Wilson by Richard Dawkins / May 24, 2012

A new book on evolution by a great biologist makes a slew of mistakes

Book review: The Social Conquest of Earth

By Edward O Wilson
(WW Norton, £18.99, May)

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My comment:

Last month (see below) I responded to a request for information about The Social Conquest of Earth. I think Dawkins’ review and Wilson’s book are like cries for help in the wilderness of evolutionary theory.

When these prominent theorists bicker, it can only mean good things for those with a better understanding of adaptive evolution/natural selection/sexual selection, via the basic principles of biology and levels of biological organization that link sensory cause directly to hormones and their affects on mammals, like us.

Wilson says we evolved via group selection. Dawkins, as always, posits the primary role of genes as replicators, as if epigenetic effects of the sensory environment are not responsible for their stochastic expression (e.g., in cells). (more…)

No New Neurons for Smell?

Excerpt: The finding may mean that as humans evolved from animals, we lost the ability to produce new neurons in this area because we don’t rely as much on our sense of smell. On the other hand, it may mean that people living in an affluent, Western city like Stockholm aren’t exposed to enough new smells to keep the neurons alive.

My comment:

Evidence for the epigenetic effects of nutrient chemicals and pheromones on mammalian olfactory bulb neurogenesis, hypothalamic neurogenesis and hippocampal neurogenesis attest to design in biology. For example, nutrient chemicals are required for survival of individual organisms in the ecological niche where pheromones control interactions in the social niche of microbes.

In the honeybee model organism, this obvious design, where nutrients and pheromones are both required, extends to brain development. What the queen bee eats determines her pheromone production and everything about the interactions of every other organism in the colony — including the neuroanatomy of the worker bees’ brains.

An extension of this model to vertebrates is found in nutrient-dependent ecological niches of the threespine stickleback that determine their social niches and speciation. Extending this model of transgenerational epigenetic inheritance from yeasts to mammals is done by examining the direct effect of nutrient chemicals, like glucose, and the direct effect of pheromones on the gonadotropin releasing hormone neurons of the hypothalamic neurogenenic niche that is responsible for luteinizing hormone secretion, fertility, steroidogenesis, sex differences in behavior, brain development (among other things), and learning and memory via hippocampal neurogenesis.

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, like the visual and auditory input associated with the development of behavior via correlates with the direct effect of nutrient chemicals and pheromones.

Is there another model for the epigenetic effects of sensory input (like food odors and social odors/pheromones) that directly effect the hormones that affect our behavior via basic principles of biology and neuroscientifically established levels of biological organization? If not, the ‘right’ model of nutrient chemical and pheromone activation of genes in hormone secreting nerve cells of brain tissue (i.e., in the organ of the organ system responsible for our behavior) suggests that the results of this study are misleading.  Positing a lesser role for olfaction or for olfactory bulb neurogenesis  in humans is inconsistent with the fact that olfaction and odor receptors provide a clear evolutionary trail that can be followed from unicellular organisms to insects to humans.

Passing On Stress

Exposure to an environmental toxin can affect future generations’ ability to handle stressful conditions.

Excerpt: “We are now in the third human generation since the start of the chemical revolution, since humans have been exposed to these kinds of toxins,” David Crews, a zoologist at the University of Texas, at Austin and one of the paper’s lead authors, said in a press release. “This is the animal model of that.”

My comment:

It is now clearer how olfactory/pheromonal input causes beneficial transgenerational epigenetic effects via direct effects of nutrient chemicals on food preferences, and the role that nutrient chemicals play in sexual reproduction via their metabolism to pheromones. From the article: “How an ancestral environmental exposure modifies the germline epigenome and promotes epigenetic transgenerational inheritance is critical in any consideration of tissue function.”  This is the gene, cell, tissue… organ (the brain) organ-system model exemplified in the honeybee model of food odors, pheromones and brain development.

In species from microbes to man receptor-mediated changes caused by nutrient chemicals and pheromones alter intracellular signaling and stochastic gene expression. Thus, olfaction and odor receptors provide a clear evolutionary trail that can be followed from unicellular organisms to insects to humans. Nutrient chemicals are responsible for the ecological niche, and their metabolism is responsible for the social niche. The ecological and social niche cause the adaptive evolution of the neurogenic niche responsible for invertebrate and vertebrate food choice and mate choice.

I was happy to see the authors express the fact that: “Although no direct epigenetic measurements were made in the current study, the epigenetic model and role of epigenetics in development provides the molecular basis of the observations presented.” Perhaps others will now proceed based on the epigenetic effects of nutrient chemicals and pheromones that have been modeled in species from microbes to man.

Clearly, this is the right model, and it’s time to use it to explain biologically based cause and effect, and to dispense with theories that cannot be modeled using the molecular biology that is common to species from microbes to man.

Human pheromone- and nutrient-dependent brain development and behavior

“Gene mapping reveals architecture that controls expression of genes responsible for our sense of smell.” May 18th, 2012. Full text of the article cited (published in March 2012).

Excerpt 1: “OR promoters have therefore characteristics of non–nervous tissue–restricted genes. In the brain, the list of tissue-restricted genes that have TATA-box, non-CpG island sharp promoters includes retina-specific genes such as opsins, retbindin, and retinal S-antigen. Resemblances in the transcriptional control of those genes may be due to a similar role as sensory transduction elements with an early origin in evolutionary history, thus sharing the more ancient type of tissue-restricted regulation that is based on sharp, TATA-boxed promoters.”

My comment 1: The early origin of olfactory receptor genes predates retina-specific genes and attests to the relative salience of olfactory/pheromonal stimuli compared to visual stimuli across species from microbes to man, since many of these species don’t have eyes.

Excerpt 2: “Among the other mechanisms that can globally control gene expression, epigenetic modifications of the DNA or the chromatin may be a good complement, for instance, to select a single locus in which interaction between a shared enhancer and the stereotyped OR core promoters would then trigger the selection of a single OR gene.”

My comment 2: This suggests that adaptation of the CAGE technique for single cells will allow them to detail how nutrient chemicals cause the receptor-mediated changes in intracellular signaling and stochastic gene expression that lead to de novo olfactory receptor gene expression.  These changes lead to new nutrient dependent ecological niches accompanied by social niches that are standardized and controlled by pheromones.

In the honeybee invertebrate model, and stickleback vertebrate model the nutrient chemicals and pheromones control brain development and speciation. These model organisms and other 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. Sex differences in brain development and behavior are as readily linked to sex differences in pheromones as they are in every other species that reproduces sexually, from yeasts to other primates. So, why is this in the current news  several months after its publication? Did someone suddenly realize that their results could be meaningfully interpreted? Shall we compare them to any other results that might be relevant to the evolution of the human brain and behavior?

If so, you start! But first, is there a model for that!

Human pheromones and the visual appeal of other people (Part one)

Groundbreaking discovery of mutation causing genetic disorder in humans

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…”

My comments:

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