Bacteria inherited by insects: Pheromones control brain development


Complex brains evolved much earlier than previously thought, 520-million-year-old fossilized arthropod confirms.Arthropods, the largest animal phylum, includes insects.

I asked: Didn’t you tell us insects were not included in the evolutionary trail I say links microbes to man? [The epigenetic effects of nutrient-dependent production of pheromones in insects is a central feature of my model.]

RKS replied: “Except for horizontal gene transfer, perhaps via viruses, insects and most invertebrates branched off and are not in our evolutionary past.  See

I think that the link exemplifies why others should probably learn more about the basic principles of biology and levels of biological organization required to link sensory cause to behavior in species from microbes to man. It is comparatively simple-minded to accept the link as if it were a factual representation of what is known. In the context of nutrient-dependent pheromone-controlled adaptive evolution of the brain and behavior, and as an alternative to the “Timeline of human evolution” link RKS provided, see this article for evidence that refutes mutations theory via inclusion of arthropods (e.g., insects) in our adaptive evolution (full text is free): Arthropods and inherited bacteria: from counting the symbionts to understanding how symbionts count.

Excerpt: “The mutational source of adaptation – a symbiont in other members of the ecological community rather than a mutation of existing genetic material – is likely to change our understanding of arthropod evolution.”

My comment: Like all adaptive evolution, arthropod evolution is nutrient-dependent and pheromone-controlled. Clearly, as indicated above, it is not caused by mutation of existing material, and most people realize the role of insect pheromones in their adaptively evolved behaviors. When the fact that differences in insect behaviors are not caused by mutations sinks in, we will be able to dispense with mutations theory.

For example, in my model, symbionts from the ecological community are transferred as nutrients. For contrast with mutations theory, “This indicates that reproduction began with an active nutrient uptake mechanism in heterospecifics and that the mechanism evolved to become symbiogenesis in the conspecifics of asexual organisms (Margulis, 1998). In yeasts, epigenetic changes driven by nutrition might then have led to the creation of novel cell types, which are required at evolutionary advent of sexual reproduction (Jin et al., 2011). These epigenetic changes probably occur across the evolutionary continuum that includes both nutrition-dependent reproduction in unicellular organisms and sexual reproduction in mammals. For example, ingested plant microRNAs influence gene expression across kingdoms (Zhang et al., 2012). In mammals, this epigenetically links what mammals eat to changes in gene expression (McNulty et al., 2011) and to new genes required for the evolutionary development of the mammalian placenta (Lynch, Leclerc, May, & Wagner, 2011) and the human brain (Zhang, Landback, Vibranovski, & Long, 2011).”

My model, for comparison to mutations theory, is based on what is currently known about conserved molecular mechanisms. When RKS or anyone else eliminates arthropods (e.g., insects) from the context of adaptive evolution, an artificial gap appears. That gap can be filled via use of mutations theory, if you are willing to accept a scientifically unsubstantiated explanation of adaptive evolution. However, it now appears that “Rapid spread of beneficial symbiont-encoded traits may be commonplace in insects. In this context, horizontal transfer through ecological interactions can serve as an immediate and powerful mechanism of rapid adaptation.”

Rapid adaptations do not fit with the bastardization of Darwinian theory, which suggests that evolution occurs via the slow accumulation of mutations, which are somehow “naturally” selected. For contrast to that slow accumulation theory, in insects “symbionts mediate variation in heat tolerance, plant use and body color [5,9]. For instance, the symbiont Rickettsiella changes the body color of the aphid host from red to green, and is thus likely to influence relative susceptibility to predators [9].”

If you remove insects from adaptive evolution in the context of the human brain and behavior, what’s left is the mutations theory:  Predators cause natural selection in moth species because they eat the moths that are more readily detected via visual cues (color against a light or dark background associated with industrial pollution that causes mutations and color change). Bring insects back into the timeline of adaptive evolution and most people will quickly realize that the pheromones produced by female moth are nutrient-dependent as is the ability of the males to detect them and fly up to 2 kilometers upwind on any given evening to find a female and mate with her.

This nutrient-dependent pheromone production and the ability of the male to find a fertile female mate is paralleled in mammals by dogs that sniff out a “bitch in heat” from far away.  The odds are incalculable that this ability would be conserved across species from insects to mammals if it were due to mutations. Those incalculable odds ensure that anyone who believes in mutation-caused adaptive evolution is about to be discovered believing in a theory made unpopular by a new model of nutrient-dependent pheromone-controlled adaptive evolution that incorporates this biological fact: “Olfaction and odor receptors provide a clear evolutionary trail that can be followed from unicellular organisms to insects to humans.”

Author: James Kohl

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