The Surprising Origins of Evolutionary Complexity Scientists are exploring how organisms can evolve elaborate structures without Darwinian selection By Carl Zimmer
My comments: Until people start asking questions about cause and effect, paradigm shifts are delayed. Now that others have begun to realize that complexity can result outside the context of what they thought Darwin wrote about “Darwian” selection, what he actually wrote can be addressed.
1) “Over generations those advantageous variations would become more common—would, in a word, be “selected.”
2) “…step-by-step, natural selection could drive this transformation to increased complexity because each intermediate form would provide an advantage over what came before.”
3). “…intricate systems of proteins can evolve from simpler ones, with natural selection favoring the intermediates along the way.”
4).”… if you start with a set of identical parts, according to McShea and Brandon, they will tend to become increasingly different from one another. In other words, the organism’s complexity will increase.”
5). “Mammals, for example, smell by binding odor molecules to receptors on nerve endings in their nose. These receptor genes have repeatedly duplicated over millions of years. The new copies mutate, allowing mammals to smell a wider range of aromas.”
6). “Natural selection will keep these mutations from spreading through populations.”
My Questions: 1). Variations are selected. How? 2). Why aren’t intermediate forms selected for their variations? 3). How does natural selection favor intermediate “intricate systems of proteins?” 4). How does complexity increase? 5). What causes the copies of receptor genes to mutate and allow mammals to smell a wider range of aromas? 6). If natural selection keeps mutations from spreading through populations how is de novo creation of olfactory receptor genes continuously enabled in conspecifics but prevented in heterospecifics?
Stories that make mutations responsible for adaptive evolution or that make operant conditioning associated with visual or auditory input responsible for adaptive evolution lack details of the molecular mechanisms or scientific support that links them to the de novo protein synthesis required for adaptive evolution.
“Zero-Force Evolutionary Law” McShea and Brandon
1) “Freed from natural selection, flies have reveled in complexity, just as the law predicts.”
2) “For an animal such as a fly to develop properly, hundreds of genes have to interact in an elaborate choreography, turning one cell into many, giving rise to different organs, and so on.”
In my model (2012), “The concept that is extended is the epigenetic tweaking of immense gene networks in ‘superorganisms’ (Lockett, Kucharski, & Maleszka, 2012) that ‘solve problems through the exchange and the selective cancellation and modification of signals (Bear, 2004, p. 330)’. It is now clearer how an environmental drive probably evolved from that of food ingestion in unicellular organisms to that of socialization in insects.”
In my model (2013), there are examples from nematodes, insects and mammals of how nutrient-dependent pheromone-controlled epigenetic tweaking of immense gene networks enables the continuum of ecological, social, neurogenic, and socio-cognitive niche construction required for adaptive evolution to occur.
Excerpt: “Mutations may disrupt that choreography, preventing the flies from becoming viable adults.”
See number 6 above: “Natural selection will keep these mutations from spreading through populations.”
Question: How does Natural Selection enable evolution in the theory of mutation-driven evolution (revised above), if natural selection prevents mutations from spreading through populations? In the peppered moth species example of industrial pollutant driven mutation and color change via natural selection by predators, birds naturally selected the lighter colored moths and ate them. In that story, natural selection by predators was for the mutants (until pollution was reduced).
Excerpt: “(Fungi and animals share a common ancestor that lived around a billion years ago.) … The fungi ended up with a more complex structure than their ancestors had. But it did not happen the way Darwin had imagined, with natural selection favoring a series of intermediate forms. Instead the fungal ring degenerated its way into complexity.”
Darwin clearly indicated on several occasions in his writings that ‘conditions of life’ precede natural selection. In my model, he was not wrong. His conditions of life are nutrient-dependent and pheromone-controlled. Natural selection for nutrients alters the microRNA/messenger RNA balance responsible for pheromone-controlled reproduction. Successful nutrient acquisition fuels the changes in seemingly futile thermodynamic cycles of protein biosynthesis and degradation that allow the epigenetic landscape to become the physical landscape of DNA. Nutrient-dependent RNA ‘editing’ results in adaptive evolution that depends on ecology (a food source), social interactions (controlled by pheromones), neurogenic niche construction (controlled by the epigenetic effects of nutrients and pheromones), and socio-cognitive niche construction, which exemplifies adaptive evolution in species that have superior learning and memory that enables more efficient foraging behaviors that promote advantageous social and sexual behaviors.
Excerpt: In other cases, such as RNA editing, scientists should not, in his view, dismiss the possibility that natural selection was at work, even if the complexity seems useless.
The compexity of Nutrient-dependent / Pheromone-controlled thermodynamics and thermoregulation is not useless. It is the cause of adaptive evolution (sans mutations theory) in species from microbes to man.