“Negative” impacts on understanding the development of intelligence and human behavior.
Molecules of deoxyribonucleic acid (DNA) contain genes. The genomes of organisms appear to self-engineer genetic changes that depend on environmental factors, which include ecological factors. The effect of the environmental factors is driven by electrical signals. For example, at the molecular level, the absorption of a single quantum of photic energy by only one of the approximately one hundred million molecules of rhodopsin contained in a single rod is sufficient to generate and transmit an electrical signal.
An afterimage shows what the brain can do with photic stimuli and three different receptors that generate electrical signals involved in visual assessment of a photographic negative.
Stare at the colored dots on this woman’s nose for 30 seconds, then quickly look at a white wall or ceiling (or anything pure white) and start blinking rapidly. Your brain processes the negative and adds color to the image you see!
The transfer from a visual signal to an electrical signal observable as color is largely responsible for the claim that the evolution of three receptors for color vision reduced the impact of pheromones on human behavior when compared to the influence of pheromones on the behavior of other primates. The argument put forth is that the evolution of ecological niches and the increased complexity of the social environment caused expansion of the primate cortex. The result was a decline in the importance of pheromonal regulation of behavior at the same time the evolution of color vision became more important to primates, including more highly intelligent humans.
This approach argues against evidence for the incentive salience of olfactory/pheromonal input across all species from microbes to man. For example, in humans, odors are transduced from chemical to electrical signals by receptors in nerve cells of brain tissue. Each of these nerve cells expresses only one of 1000 olfactory receptors. All possible combinations of a blend of one set of twenty odors would yield over one million unique mixtures. No one has calculated how many odors each of us might be exposed to during our life, but it is safe to say that many millions of unique mixtures of twenty or more odors are possible.
In the context of our uniquely individual experiences, we can compare color vision and the discriminatory power of the brain when it processes olfactory/pheromonal input associated with food odors or pheromones. The comparison depends only on what is known about the complexity of mathematical calculations; self-engineering of genetic changes; and the discriminatory power of other animals that contain the genomes of species from microbes to man.
Self-engineering of genetic changes enables self / non-self recognition in other organisms. This ensures bacteria do not eat conspecifics, but are willing to dine on the DNA of heterospecifics. When no food is available, bacteria respond to the pheromones of conspecifics and cease reproduction. Unlike some species, they do not cannibalize each other, and they do not sexually reproduce. When sufficient food enables fertility and sexual reproduction in other species, the pheromones of a potential non-self mate of the opposite sex signal an opportunity for sexual reproduction.
In mammals, food odors and pheromones cause the electrical activation of genes in nerve cells of brain tissue. This links them directly to behavior via the required gene, cell, tissue, organ, organ system pathway (Kohl, submitted).
Now that you have seen with your own eyes what can be done by your brain to add color to your life via only three different receptors, perhaps you can better imagine the role that your mind’s eyes play in the development of behavior associated with olfactory/pheromonal input. Food odors and pheromones play the most important role of sensory input in any species.
Even though you cannot see the olfactory/pheromonal input activating the genes that self-engineer genetic changes, the relative incentive salience of environmental and social factors like food odors and pheromones should be as clear as the misrepresentations of cause and effect associated with the evolution of primate color vision.