Date: January 28, 2014
Summary: New research suggests a surprising degree of similarity in the organization of regions of the brain that control language and complex thought processes in humans and monkeys. The study also revealed some key differences. The findings may provide valuable insights into the evolutionary processes that established our ties to other primates but also made us distinctly human.
Excerpt: “…some uniquely human cognitive traits may rely on an evolutionarily conserved neural apparatus that initially supported different functions. Additional research may reveal how slight changes in connectivity accompanied or facilitated the development of distinctly human abilities.”
My comment: How is a trait that is associated with a neural apparatus evolutionarily conserved, if not by natural selection? That question can now be asked in the context of language development because four of the five co-authors on the study reported above are about to link ecological variation to what may be another powerful refutation of mutation-initiated natural selection. When it’s available see “A neural circuit covarying with social hierarchy in macaque. Do they realize they may be refuting the theory of mutation-initiated natural selection? Do they understand how this neural circuit covaries with ecological niche construction and socialization in other species?
For example, ecological adaptations clearly result in nutrient-dependent pheromone-controlled changes in the microRNA (miRNA)/ messenger RNA balance that lead to a post-transcriptional mechanism that regulates FOXP2 expression in a miRNA-FOXP2 gene regulatory network. That regulatory network is involved in the social context of singing in zebra finches (Shi et al., 2013).
The FOXP2 transcription factor plays a role in speech and language in humans. It is also highly conserved from mice to humans, differing at only 3 amino acid positions (Adipietro, Mainland, & Matsunami, 2012). Two extinct hominim species that supposedly diverged from the human lineage 400–800 kya differ from other primates and differ from humans by the same two amino acid substitutions in the FOXP2 gene. “Some researchers have speculated that the two amino acid differences between chimps and humans led to the evolution of language in humans.” But wait, how were the two amino acid differences naturally selected to result in the evolution of language in humans, if they resulted from mutations during hundreds of millions of years of vertebrate evolution? Are the researchers speculating or simply guessing that something, a mutation (perhaps) “just happens” to be naturally selected in all vertebrates?
There is experimental evidence that suggests what actually happens. In humans, the FOXP2 gene encodes a transcription factor that regulates the expression of many downstream genes, which in turn have important roles in changes in brain connectivity and in nervous system development and function (Somel, Liu, & Khaitovich, 2013). Taken together, the evidence for the roles played by nutrient-dependent pheromone-controlled FOXP2 gene expression in finches, mice, other primates, extinct hominims and modern humans makes it more difficult for me to consider FOXP2 gene expression in different species in the context of mutation-driven evolution. It seems clear that FOXP2 has been subject to accelerated ecological adaptations, which are clearly evidenced by amino acid changes that led to differentiated molecular functions in human compared to great apes and other species (see for review Shulha et al., 2012).
I reiterate, I do not think it is reasonable to assume; to believe; or to try to teach others to believe that the developmental staging of human speech and language is mutation-enabled and somehow arises via natural selection for mutations. Instead, I think it is reasonable to consider the developmental staging of human speech and language in the context of:
1) the conserved molecular mechanisms of de novo creation of genes via
2) nutrient-dependent pheromone-controlled changes in intracellular signaling that
3) enable experience-dependent receptor-mediated stochastic gene expression,
4) alternative splicings of pre-mRNA,
5) amino acid substitutions and
6) chromosomal rearrangements that enable different species-specific functions associated with
7) multisensory integration, socialization and with
8) the ecological adaptations that led to human language ability.
Steven Pinker recently suggested in an interview that our language ability should be approached from what is currently known about genetics and the functionally conserved molecular mechanisms that link the sensory environment to adaptively evolved behaviors during their development. I disagree. I think our language ability must be approached from what is currently known about ecological variations and nutrient-dependent pheromone-controlled adaptations.
Nutrient-dependent de novo creation of the FOXP2 gene in finches and regulation of its expression in the social context of singing links olfactory/pheromonal input to regulation of the gene’s expression during the development of human speech and language via conserved molecular mechanisms across vertebrate species that link bird odor and reproductive success.
It recently became clear that Jay R. Feierman, who moderates the International Society of Human Ethology (ISHE) yahoo group, is probably monitoring my blog posts and selectively representing the information I am offering here as if he came to it on his own. That’s why on a few recent occasions I have not provided full references to the works I have cited. However, I am providing full citations here since it no longer makes a difference where the refutations of mutation-driven evolution come from.
What might make a difference is if ISHE forced Feierman to apologize to me for blocking the dissemination of accurate information about biologically-based cause and effect in species from microbes to man. See, for example “Problems created by J. Kohl” where Prof. Dr. Wulf Schiefenhövel addressed the problems Feierman told him I created.
PROBLEM-CAUSING REFERENCES TO ACCURATE REPRESENTATIONS OF BIOLOGICALLY-BASED CAUSE AND EFFECT
Adipietro, K. A., Mainland, J. D., & Matsunami, H. (2012). Functional Evolution of Mammalian Odorant Receptors. PLoS Genet, 8(7), e1002821.
Shi, Z., Luo, G., Fu, L., Fang, Z., Wang, X., & Li, X. (2013). miR-9 and miR-140-5p Target FoxP2 and Are Regulated as a Function of the Social Context of Singing Behavior in Zebra Finches. The Journal of Neuroscience, 33(42), 16510-16521.
Shulha, H. P., Crisci, J. L., Reshetov, D., Tushir, J. S., Cheung, I., Bharadwaj, R., et al. (2012). Human-Specific Histone Methylation Signatures at Transcription Start Sites in Prefrontal Neurons. PLoS Biol, 10(11), e1001427.
Somel, M., Liu, X., & Khaitovich, P. (2013). Human brain evolution: transcripts, metabolites and their regulators. Nat Rev Neurosci, 14(2), 112-127.