Excerpt: “Particular single nucleotide polymorphisms are associated with core deficits of children with specific language impairment and also coincide with language delays in autistic children . In songbirds, CNTNAP2 is differentially expressed in some song control nuclei, but whether FoxP2 regulates CNTNAP2 in songbirds has not yet been addressed . These findings are encouraging in the light of potential deep homologies between human speech and bird song.”
My comment: Bird song and speech homologies now extend from microbes to insects and from birds to man via an unbroken biophysically constrained hierarchy of nutrient-dependent pheromone-controlled ecological adaptations.
Alternatively, constraint-breaking mutations may link morphological and behavioral phenotypes across species. However, there is no model or model organism that can be used to support those assertions. That’s why some researchers consider those assertions to be nothing more than pseudoscientific nonsense, since no biologically-based experimental evidence supports such ideas.