Human pheromones and inner conflict about evolution (1102 words)

June 24, 2012, 5:00 pm 234 Comments

Evolution and Our Inner Conflict


Excerpt with my emphasis: “Within biology itself, the key to the mystery is the force that lifted pre-human social behavior to the human level. The leading candidate in my judgment is multilevel selection by which hereditary social behavior improves the competitive ability not of just individuals within groups but among groups as a whole. Its consequences can be plainly seen in the caste systems of ants, termites and other social insects.”


My comment: “I should think we might fairly gauge the future of biological science, centuries ahead by estimating the time it will take to reach a complete comprehensive understanding of odor. It may not seem a profound enough problem to dominate all the life sciences, but it contains, piece by piece, all the mysteries.” — Lewis Thomas (1980) as cited in The Scent of Eros: Mysteries of Odor in Human Sexuality (1995/2002)

The force that lifted us from “pre-human social behavior to the human level” was predicted by Lewis Thomas, who allowed me to conclude more than three decades later that “Olfaction and odor receptors provide a clear evolutionary trail that can be followed from unicellular organisms to insects to humans (Kohl, 2012).”  Wilson errs when he misses the apparent design in the biology of species that “…can be plainly seen in the caste systems of ants, termites and other social insects…” He apparently can’t see that the apparent design includes the role of pheromones in species from microbes to man.

The concept of “core words” is important here, which is why they are in bold typeface. My model details the ecological, social, neurogenic, and socio-cognitive niche construction that is required for adaptive evolution of species from microbes to man. The details include what is now known about the only pathway that links sensory input directly to behavior. That’s the gene, cell, tissue, organ, organ system pathway, and it starts with an absolute requirement for gene activation in cells.

Using core words makes my model sound complicated, so I uncomplicated the model by using the honeybee model organism as an example. Model organisms make core words easier to understand by placing them in their proper context.

Here’s the simplified context. What the honeybee queen eats determines her pheromone production. Her pheromones determine everything else about the social interactions of the colony including the neuroanatomy of the worker bees’ brains. In the context of the requirement for proper nutrition and ongoing exposure to pheromones from other members of your species, the honeybee model organism makes my model of multilevel selection easy to understand. Simply put, we are what we eat and our pheromones tell others what we are and who we are. In my model there’s no switch from the basic principles of biology in all species to a theoretical perspective exclusive to some of the non-human primates and all humans. My model, for example, is not a theory that excluded human pheromones. And the entirety of the published work that details the model is only 10 pages long, which includes 3 pages of references.

I don’t think I’ve missed anything that is touted by others who espouse various theories of adaptive evolution inside or outside the context of the required biology. If I have missed something essential to multilevel selection, as portrayed by E.O. Wilson, no one has told me what’s missing. And if Wilson had merely taken what he knows about eusocial insects and kept the pheromonal perspective as he extended his thoughts on adaptive evolution to multilevel selection in humans, his portrayal of group selection might make more sense.

Instead, he confuses everyone with a switch. There’s one model of nutrient-dependent and pheromone-dependent adaptive evolution in species from microbes to insects, like eusocial ants and honeybees. Then there is the switch to a nutrient-dependent model of group selection (i.e., multilevel selection) without pheromones in humans. Let me make this perfectly clear. Wilson switches from one model of multilevel selection:

1)      ecological,

2)      social,

3)      neurogenic, and

4)      socio-cognitive niche construction.

He excludes level 2): our social odors, called human pheromones.

That leaves him the task of explaining how multilevel selection occurs via

1)      ecological,

2)      neurogenic, and

3)      socio-cognitive niche construction.

Without human pheromones, nothing enables the required socio-cognitive niche construction. In contrast, in every other species both nutrient chemicals and pheromones are required for adaptive evolution – as exemplified in the honeybee model organism and in many other model organisms from yeasts to mammals.

Clearly, neither Wilson, nor anyone else can simply skip from ecological to neurogenic and socio-cognitive niche construction, without missing something important to cognitive niche construction, i.e., the social component of socio-cognitive niche construction. Without pheromone-driven social niche construction, evolutionary theorists eliminate the role of pheromones in sexual differentiation and in the development of sexual preferences. In my model, that is like eliminating the role of food odors associated with the nutrient chemicals that are responsible for ecological niche construction and the development of human food preferences. Yet food acquisition and preferences for ‘brain food’ are central to Wilson’s theory of group selection.

Wilson’s in-congruent approach to multilevel/group selection (e.g., sans pheromones) is similar to an approach that tells us nutrient chemicals and food odors are not as important to selection in humans as they are in other species. My approach explains the importance of the epigenetic effects of both nutrient chemicals and pheromones.

Without the epigenetic effects of nutrient chemicals, organisms die. Starving organism selects for nothing at any level of multilevel selection and they are not ‘fit’ to reproduce. Well nourished organisms are fit to reproduce and the metabolism of nutrient chemicals to pheromones allows them to signal their reproductive fitness. Without the epigenetic effects of pheromones, species do not survive because there are no other signals of reproductive fitness that directly activate genes (in cells, as required for adaptive evolution). It’s food first, then pheromones. Their combined effect of food and pheromones on neurogenic niche construction is responsible for the adaptive evolution of the human brain which enabled construction of our socio-cognitive niche. There is no other model for that, just theories — in all their incongruent glory. Wilson missed the opportunity to make his latest theory consistent with what is currently known about the molecular biology common to all species from microbes to man, but he is probably closer than most. Maybe he will add back human pheromones in the next rendition of his series of theories and incorporate the biology of behavior as he did in his initial works.

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

Author: James Kohl

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