So your claim is that the human brain is adaptable enough that it can rewire itself in reasonable ways in response to sense input, but so rigid that there are no easy mutations that would correspond to some of the behavioral changes evolutionary psychologists talk about.
The brain is adaptable, but the development process isn’t. You connect neurons by steering the growth cones through chemical gradients. Using the genes that affect large number of neurons at once.
Consider a centipede with, say, 40 segments. It is so flexible that it can lose a lot of legs and still walk, yet so rigid that you’ll have real trouble making a mutation which affects just the 27th segment (losing legs on it), requiring a lot of generations to specialize an ancient centipede into an insect (or spider, or crustacean). Why so? Because there aren’t 40 segments in the DNA, there’s 5..6 cell divisions when making cells that become the segments later. You need a whole lot of regulatory genes to just start addressing the segments individually from DNA. The DNA is not a blueprint.
That being said, I do agree that brain’s neuroplasticity can take advantage of some mutation that’s bridging two areas of the brain. How to use the data that comes over the bridge, however, is up to neuroplasticity to figure out.
You connect neurons by steering the growth cones through chemical gradients. Using the genes that affect large number of neurons at once.
Directly effecting neural growth patterns isn’t the only way for genes to effect human behavior. Consider for example, the effect on human behavior of drugs like caffeine, alcohol, anti-depressants, etc. Keep in mind any drug effect can be approximately stimulated by affecting any of the steps in the chemical cascade the drug uses.
Indeed. I’m not at all against the notion that the existing mechanisms can be adapted by evolution—whenever those are coded for. You can, most definitely, up or down regulate e.g. dopamine activity.
That is far cry from emergence of specialized modules, as per “organized into modules or mental organs, each with a specialized design that makes it an expert in one arena of interaction with the world. The modules’ basic logic is specified by our genetic program. Their operation was shaped by natural selection to solve the problems of the hunting and gathering life led by our ancestors in most of our evolutionary history” (Pinker 1997a, p. 21).
So your claim is that the human brain is adaptable enough that it can rewire itself in reasonable ways in response to sense input, but so rigid that there are no easy mutations that would correspond to some of the behavioral changes evolutionary psychologists talk about.
The brain is adaptable, but the development process isn’t. You connect neurons by steering the growth cones through chemical gradients. Using the genes that affect large number of neurons at once.
Consider a centipede with, say, 40 segments. It is so flexible that it can lose a lot of legs and still walk, yet so rigid that you’ll have real trouble making a mutation which affects just the 27th segment (losing legs on it), requiring a lot of generations to specialize an ancient centipede into an insect (or spider, or crustacean). Why so? Because there aren’t 40 segments in the DNA, there’s 5..6 cell divisions when making cells that become the segments later. You need a whole lot of regulatory genes to just start addressing the segments individually from DNA. The DNA is not a blueprint.
That being said, I do agree that brain’s neuroplasticity can take advantage of some mutation that’s bridging two areas of the brain. How to use the data that comes over the bridge, however, is up to neuroplasticity to figure out.
Directly effecting neural growth patterns isn’t the only way for genes to effect human behavior. Consider for example, the effect on human behavior of drugs like caffeine, alcohol, anti-depressants, etc. Keep in mind any drug effect can be approximately stimulated by affecting any of the steps in the chemical cascade the drug uses.
Indeed. I’m not at all against the notion that the existing mechanisms can be adapted by evolution—whenever those are coded for. You can, most definitely, up or down regulate e.g. dopamine activity.
That is far cry from emergence of specialized modules, as per “organized into modules or mental organs, each with a specialized design that makes it an expert in one arena of interaction with the world. The modules’ basic logic is specified by our genetic program. Their operation was shaped by natural selection to solve the problems of the hunting and gathering life led by our ancestors in most of our evolutionary history” (Pinker 1997a, p. 21).