- THE LOOM:
by Carl Zimmer
Excerpt: “You may also want to check out P.Z. Myers’s critique of the “tether hypothesis” on his blog Pharyngula. He raises some important questions about the idea, based on his own experiences as a neuroscientist. I’m puzzled, though, why he decided to kick it off with this swipe at me…”
My comment: It is obvious that he took a swipe at Zimmer for again making nonsense from what makes sense to biologists. Even the expert who Zimmer consulted knows about the role of nutrient-dependent amino acid substitutions in human brain development. Did Zimmer ignore the fact that a glucose-dependent duplication of the glutamate dehydrogenase gene took place, which led to amino acid substitutions that characterize hominoid variants of new genes that appear to enhance the ability of mitochondria to provide energy to neurons in the developing brain?
But wait, there’s even more of what may be Zimmer’s ignorance. His expert also knows that two additional amino acid substitutions show up in the context of comparisons with other primates. For example, the amino acid sequence of the FOXP2 gene is highly conserved across mammals and the amino acid sequences are identical in rhesus macaques, gorillas, and chimpanzees. Thus, the additional amino acid substitutions in humans appear to be the clearest link to the neuroscientifically established ability to talk and to understand what others are saying. Does Zimmer understand anything about the role of nutrient-dependent amino acid substitutions in any cell type? His focus appears to become published work that reiterates the importance of what can be learned from brain imaging about the development of the human brain: Nothing!
Panksepp said it best, and I love to quote from the paper that won the same award for his group that my group won a year earlier. But, let me keep it simple. In an interview, Panksepp said: “If you don’t understand the foundational level, then you can do brain imaging until you’re blue in the face, but you still will not understand the process at a deep causal level.” Therein lies the problem that Zimmer appears to have, and that PZ Myers tries to address. Here’s what he says you don’t need to get your work reviewed by Carl Zimmer: You know what you don’t need? Data, or a hypothesis that makes sense. Zimmer seems willing to block all of my comments on his reviews, but Myers did not block this one.
Tethering hypotheses to the holy grail of evolutionary biology via molecular epigenetics and de novo gene creation.
“The epigenetic effects of nutrients and pheromones extend across the life history of organisms, but from 1996 to 2012 the concept of molecular epigenetics and epigenetic effects on hormone-driven adaptive evolution of the human brain and behavior seems to have gone missing. Evolutionary psychologists and other social scientists, for example, refused to tether their hypotheses to a new discipline called ‘neuroevolutionary psychobiology’, to neurogenetics (Zoghbi & Warren, 2010), or to any biologically based discipline whatsoever (see for review Panksepp, Moskal, Panksepp, & Kroes, 2002). More than five decades of progress that directly links molecular epigenetics to behavior has been virtually ignored (Shapiro, 2012), but see Ledón-Rettig, Richards, and Martin (2012).”
My comment: Buckner had the opportunity to tether his review, and Zimmer had the opportunity to tether his comments, to what is currently known about de novo gene creation, which occurs via one signaling pathway that links nutrient uptake to pheromone-controlled reproduction in species from microbes to man. For example, it is easy to start with ecological, social, and neurogenic niche construction and link it from grazing nematodes to predatory nematodes by a nutrient-dependent single amino-acid substitution, which is associated with the development of teeth in the predator and rewiring of the most primitive neuronal system to result in dramatic differences in behavior.
So where’s the hypothesis? Dobzhansky (1964) was critical of anyone who was not interested in what I just wrote. Fifty years ago., he wrote: “The notion has gained some currency that the only worthwhile biology is molecular biology. All else is “bird watching” or “butterfly collecting.” Bird watching and butterfly collecting are occupations manifestly unworthy of serious scientists!”
Dobzhansky also noted the finding, in sickle-cell disease “‘…that hemoglobin S differs from A in the substitution of just a single amino acid, valine in place of glutamic acid in the beta chain of the hemoglobin molecule.”
Why is Buckner ignoring the fact that amino acid substitutions differentiate cell types in individuals of the same species and different species. These amino acid substitutions explain differences in the olfactory receptor genes of individual humans, and they arise via the de novo experience-driven intercellular signaling and transcription / gene expression capacity of the genome.
Why is it that Zimmer appears to be just now beginning to realize that what has been neuroscientifically known for decades refutes the concept of mutation-initiated natural selection in the context of the development of the human brain? Did anyone seriously think that our conspecifics somehow selected carriers of the sickle-cell variant? If the variant was a mutation that was not selected, how it remain in the context of the evolution of the human brain?
Zimmer’s NY Times article concluded: “The emergence of the human mind might not have been a result of a vast number of mutations that altered the fine structure of the brain. Instead, a simple increase in the growth of neurons could have untethered them from their evolutionary anchors, creating the opportunity for the human mind to emerge.”
My comment: If you know any other science journalist who does not seem to realize the importance of nutrition and ecological adaptations, which biologists have attributed to species diversity since Dobzhansky (1964), please let either P.Z. Myers, or me, know who they are. In my opinion, Zimmer may remain a lost case when it comes to learning anything from the experts, but perhaps others can be helped. However, I am also concerned that Zimmer or someone like him will suddenly develop what appears to be their expertise on the topic of amino acid substitutions and the de novo creation of genes, and continue to ignore or block my comments on their misrepresentations until they finally begin to get it right. Ecological, social, neurogenic, and socio-cognitive niche construction are nutrient-dependent and pheromone-controlled.