Could humans have evolved a parietal eye (or perhaps a “pineal eye”) which then migrated to the back of the head?
It is worth saying, though tautologically true, that evolution can’t do what evolution can’t do, and that the genetic code for new structures and functions has to be combinatorially accessible to the evolving genome. But the modularity of genetic regulatory networks (GRNs) can produce big rearrangements at a single step: redirection of a single “pointer variable” could see hardwired data structures and algorithms evolved within one sensory/cognitive module suddenly duplicated within a new brain region. (See the idea of William Calvin and Derek Bickerton that nested syntax resulted from transposing tree structures used in arm-hand-finger coordination to vocal communication.) Alternatively, polyploid mutations can duplicate at the genetic level a whole GRN, which permits divergent evolution of recycled algorithms—the tree structures for syntax could then be modified without impairing manual dexterity.
So your point is valid, but don’t underestimate the power of evolution!
It is worth saying, though tautologically true, that evolution can’t do what evolution can’t do, and that the genetic code for new structures and functions has to be combinatorially accessible to the evolving genome.
It is worth adding that evolution can’t do most of the things that evolution could do either. At least not in one instance like that which we see.
Big rearrangements at a single step leave you with disabled individuals. That’s how we didn’t evolve the third eye, too.
It is certainly possible to evolve a third eye on back of the head, but that takes several steps going in different direction, a very huge number of generations, and it most certainly is extremely unlikely in such brief timeframe.
One shouldn’t invoke that sort of change unless one first demonstrates that this extremely unlikely path is positively the most likely way in which nested syntax can arise. They didn’t demonstrate so; they just have very strong prejudice; that’s what rationalizations are.
The neuroplasticity being what it is, it appears we don’t need conjunctions of multiple highly unlikely events such as this as explanation for the nested syntax.
Could humans have evolved a parietal eye (or perhaps a “pineal eye”) which then migrated to the back of the head?
It is worth saying, though tautologically true, that evolution can’t do what evolution can’t do, and that the genetic code for new structures and functions has to be combinatorially accessible to the evolving genome. But the modularity of genetic regulatory networks (GRNs) can produce big rearrangements at a single step: redirection of a single “pointer variable” could see hardwired data structures and algorithms evolved within one sensory/cognitive module suddenly duplicated within a new brain region. (See the idea of William Calvin and Derek Bickerton that nested syntax resulted from transposing tree structures used in arm-hand-finger coordination to vocal communication.) Alternatively, polyploid mutations can duplicate at the genetic level a whole GRN, which permits divergent evolution of recycled algorithms—the tree structures for syntax could then be modified without impairing manual dexterity.
So your point is valid, but don’t underestimate the power of evolution!
It is worth adding that evolution can’t do most of the things that evolution could do either. At least not in one instance like that which we see.
Big rearrangements at a single step leave you with disabled individuals. That’s how we didn’t evolve the third eye, too.
It is certainly possible to evolve a third eye on back of the head, but that takes several steps going in different direction, a very huge number of generations, and it most certainly is extremely unlikely in such brief timeframe.
One shouldn’t invoke that sort of change unless one first demonstrates that this extremely unlikely path is positively the most likely way in which nested syntax can arise. They didn’t demonstrate so; they just have very strong prejudice; that’s what rationalizations are.
The neuroplasticity being what it is, it appears we don’t need conjunctions of multiple highly unlikely events such as this as explanation for the nested syntax.