system
Given the following post, respond as if you're commenting on Reddit:
human
If genetic mutations are random, and only later sorted according to the advantage or disadvantage they yield during the struggle to reproduce, why don't we see more functionally neutral traits?

A thumbnail sketch of evolution might go as follows: Sexual reproduction throws up genetic mutations which result in random variations in the resulting offspring of two organisms. If these random variations give the organism a slight advantage, it is more likely to survive and pass on its genes; if they do not, it is more likely to perish before reproductive age  and therefore fail to pass on those unfit genes.

We might summarize this still further by saying with Dawkins that reproduction is a sort of "combinatorial lottery" upon the results of which survival on earth exerts a selective force. But in that case the rules of the game are, “Anything goes,” followed by, “If it works once it’s here, it stays; if it doesn’t work, it's out,” with nothing to account for the conspicuous absence of functionally redunant attributes.

To put it slightly differently, if the above outline of evolution is valid might we not expect to see more animals with traits that offer NEITHER an obvious survivalistic advantage NOR a disadvantage? But looking at any particular organism on earth, one is impressed by how amazingly streamlined and efficient it is. You can say, “The spinal cord is poorly ‘designed,’” or else, “The optic nerves of the eye whorl back rather uneconomically through the pupil,” or whatever. But nevertheless, there seems to be zero fat or shoe-leather on Earth's organisms in that every trait, organ and feature serves a particular, easily identifiable and necessary purpose.

What I am struggling to express and understand, to conclude, is that the mechanism of evolution allows for the emergence and persistence of functionally neutral traits but that these are rarely if ever seen. 

As an example, let's imagine that twenty-thousand years ago a dragonfly is born with a larger mandible that enables it to consume a more varied died—but this trait is randomly paired with a nodule on its back. The advantage of an increased jaw size offsets whatever energy is squandered growing the nodule and so a selection bias emerges for the paired traits. But millennia later scientists will face a conspicuous feature of dragon-fly anatomy with no identifiable function.

I'm a mere artist and this is no doubt a crude example but it is easy to extract the basic idea and imagine the rich variety of traits of neutral functionality that might exist if evolution were random and the only selection force the advantageousness or disadvantageousness of the resulting variations  because *there is no selection force operating upon functional redundancy.*
gpt
Most mutations are neutral. (This is sort of a trick, most are going to be silent. They are neutral because they don't change any morphology.) You are confusing traits with sequence. Traits are things like arms. It does not really make sense to talk about a trait being neutral, neutral is in comparison. All traits help the organism, having something is expensive. Most *changes* are in fact neutral. A small number are positive, some of those make it to fixation (stick around), a larger number are negative and far fewer of those make it to fixation.