Evolution of mosquito preference for humans linked to an odorant receptor
Excerpt: “Our results also provide insight into the molecular basis of behavioural evolution.”
See their diagram in Extended Data Figure 3: Amino acid differences of major Or4 protein alleles.
Excerpt: Dots represent amino acid differences with respect to the genome reference, not an inferred ancestor.
Excerpt: The switch from preferring animals to humans involves a variety of behavior adjustments: Mosquitoes had to become comfortable living around humans, entering their homes, breeding in clean water found in water jugs instead of the muddy water found in tree holes. “There’s a whole suite of things that mosquitoes have to change about their lifestyle to live around humans,” Vosshall says. “This paper provides the first genetic insight into what happened thousands of years ago when some mosquitoes made this switch.”
My comment: In my model, nutrient-dependent amino acid substitutions stabilize DNA in the organized genome of species from mosquitoes (and microbes) to man but the substitutions are not linked via to any ancestor via evolution.What happened thousands of years ago is most readily attributed to a nutrient-dependent amino acid substitution and metabolism of nutrients to species specific pheromones that control the physiology of reproduction, which results in fixation of the amino acid substitution in the populations that were studied. Fixation of beneficial amino acid substitutions can be compared to the detrimental effects of mutations on protein folding that prevents the de novo creation of olfactory receptor genes associated with food odors.
See also: orco mutant mosquitoes lose strong preference for humans and are not repelled by volatile DEET
Excerpt: “We conclude that the odorant receptor pathway is crucial for an anthropophilic vector mosquito to discriminate human from non-human hosts…”
Their diagram and Excerpt: orco mutants exhibited severely impaired electrophysiological responses
My comment: I reiterate (from above) “There’s a whole suite of things that mosquitoes have to change about their lifestyle to live around humans…” Mutations appear to eliminate the suite of things that must occur in the context of nutrient-dependent pheromone-controlled fixation of amino acid substitutions linked to the behavior of mosquitoes.
Our 1996 model of RNA-mediated events links the molecular epigenetics of the nutrient-dependent pheromone-controlled physiology of reproduction to increasingly complex morphological and behavioral phenotypes in species from microbes to man. Nothing suggests mutations are beneficial or that they could be linked to biodiversity via natural selection and evolution. Instead, the model forms the basis for claims made in Elekonich and Robinson (2000), which link the model to insects and claims made in Elekonich and Roberts (2005) that link the model to life history transitions in the honeybee model organism. Additional evidence that supports our link from pheromones to the physiology of reproduction in mammals is was reported in
Excerpt: “…we now show how in the first hours of drawing breath it also triggers our brains to develop differently according to our sex.”
The need for pre-natal and post-natal development of sexually dimorphic olfactory systems that respond to similar food odors but differences in pheromones was clarified in the context of The Mind’s Eyes: Human pheromones, neuroscience, and male sexual preferences.
LeVay summarized his thoughts on extension of our 1996 model to sexual preferences in Gay, Straight, and the Reason Why: The Science of Sexual Orientation. (p. 210)P
“This model is attractive in that it solves the “binding problem” of sexual attraction. By that I mean the problem of why all the different features of men or women (visual appearance and feel of face, body, and genitals; voice quality, smell; personality and behavior, etc.) attract people as a more or less coherent package representing one sex, rather than as an arbitrary collage of male and female characteristics. If all these characteristics come to be attractive because they were experienced in association with a male- or female-specific pheromone, then they will naturally go together even in the absence of complex genetically coded instructions.”
“Still, even in fruit flies, other sensory input besides pheromones…”
Few people would foolishly argue that food odors associated with nutrient uptake and pheromones associated with controlled reproduction could be less important that any other sensory input that might somehow link the epigenetic landscape to the physical landscape of DNA in the organized genomes of species from microbes to man. Similarly, it is not likely that anything is more important than species-specific pheromones to the control of reproduction. Thus, the role of food odors and pheromones can be compared in the context of a recently reported link between blood-sucking mosquitoes and predatory mammals. See:
Excerpt: “…the results demonstrate that a single blood odor component can be as efficient in eliciting behavioral responses in large carnivores as the odor of real blood, suggesting that trans-4,5-epoxy-(E)-2-decenal may be perceived by predators as a “character impact compound” of mammalian blood odor.”
My comment: Food odors, which epigenetically effect hormones that affect behavior are considered in the context of ‘character impact compounds.’ Will pheromones continue to be considered in the context of anything that does not directly link the nutrient-dependent odor-controlled physiology of reproduction to epigenetically-effected hormones that affect species-specific behaviors via conserved molecular mechanisms of RNA-mediated amino acid substitutions and cell type differentiation in species from microbes to man? If so, the word-play of evolutionary theorists and semi-serious scientists will have won their game. Few people will learn that ecological variation is linked to ecological adaptations only via nutrient uptake and the pheromone-controlled physiology of reproduction. Most may continue to think that mutations and/or natural selection can somehow be linked to the evolution of biodiversity because that is what they have been taught to believe.
For comparison see:
Human pheromones and food odors: epigenetic influences on the socioaffective nature of evolved behaviors
Conclusion: “Olfaction and odor receptors provide a clear evolutionary trail that can be followed from unicellular organisms to insects to humans…”
Conclusion: “Minimally, this model can be compared to any other factual representations of epigenesis and epistasis for determination of the best scientific ‘fit’.”