How would understanding systems have been significantly adaptive for humans before a few thousand years ago? I agree with you that humans generally lack this capability. We also lack the ability to understand exponential growth, which I think is partially a cause of our lack of ability to comprehend systems.
My personal theory on this is that it comes from the fact that our sensory systems operate on a logarithmic response curve [0]. Note, for instance, how the decibel scale for measuring sound intensity is a logarithmic scale. Because our sensory systems respond logarithmically, that means an exponential increase in stimulus feels linear, at least until the point where the stimulus is damaging or so intense as to be uncomfortable. The end result is that we think "it's not so bad" until it's really bad.
I find your perspective interesting, but have the feeling that you are not thinking in systems (!). The sensory systems are perceptual systems, but they are subsystems of a larger "cognitive" system, and we cannot be sure that it exhibits the same logarithmic response behavior.
My personal theory on this is that it comes from the fact that our sensory systems operate on a logarithmic response curve [0]. Note, for instance, how the decibel scale for measuring sound intensity is a logarithmic scale. Because our sensory systems respond logarithmically, that means an exponential increase in stimulus feels linear, at least until the point where the stimulus is damaging or so intense as to be uncomfortable. The end result is that we think "it's not so bad" until it's really bad.
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[0]: https://en.wikipedia.org/wiki/Weber%E2%80%93Fechner_law