There is even less hope for improving the properties and components of the organism that are far from ideal. The vertebrate eye is often cited as an example of excellence, but it also has significant design flaws. A bundle of blood vessels and nerve fibers is passed into the eye through a hole in the fundus, creating a blind spot, and then the nerve fibers diverge right along the surface of the retina. Why don’t they go to the light-sensitive cells not along the retina, but behind it, like an octopus? But nothing can be changed. Natural selection cannot correct this constructive flaw, since it would have to doom thousands of generations to blindness.
There is plenty of similar hack in the brain, which is prone to all sorts of thinking errors because of this. Some of them stay with us for the same reason as the blind spot in the eye: it is impossible to return to the starting point and redo everything again. And even if developmental momentum is not taken into account, much of our susceptibility to mental illness is due to limited selection. There is no way without mutations.
There are problems that natural selection cannot deal with.
Much is simply beyond the control of natural selection. None of the systems are capable of copying genetic information perfectly accurately, so mutations are inevitable. Natural selection cannot change the laws of physics, so we won’t have flying elephants. Selection is unable to form an organism that produces its own energy and does not need its other sources. These limitations are inherent in any system, both natural and mechanical.
Among other things, the inertia of development interferes with the achievement of absolute perfection for both the engineering structure and the body. When the trajectory of development has already been set, you will not be able to start over. An example is a computer keyboard: you can change to some more efficient layout, but for this you will have to retrain, and it will be incompatible with the meaning of the keys on the existing keyboard.
There is even less hope for improving the properties and components of the organism that are far from ideal. The vertebrate eye is often cited as an example of excellence, but it also has significant design flaws. A bundle of blood vessels and nerve fibers is passed into the eye through a hole in the fundus, creating a blind spot, and then the nerve fibers diverge right along the surface of the retina. Why don’t they go to the light-sensitive cells not along the retina, but behind it, like an octopus? But nothing can be altered. Natural selection cannot correct this constructive flaw, since it would have to doom thousands of generations to blindness.
There is plenty of similar hack in the brain, which is prone to all sorts of thinking errors because of this. Some of them stay with us for the same reason as the blind spot in the eye: it is impossible to return to the starting point and redo everything again. And even if developmental momentum is not taken into account, much of our susceptibility to mental illness is due to limited selection. There is no way without mutations.