While I don't disagree that humans are essentially at the lowest level of intelligence that make civilization possible (else why would it have taken hundreds of thousands of years to get started?), this claim has no bearing on the claim that the upper limit of intelligence is immediately above human genius level.
But there's no particular reason to believe that the upper limit of intelligence is pretty much right where we are, either.
In fact, I'd argue that based on what we know about other evolved systems, our priors for "the biologically evolved system that does X has plenty of room for improvement" should be much, much, much higher than "the biologically evolved system for X is almost optimal for achieving X".
Like, a thousand to one or more - there are very few tasks that evolution has found optimal solutions to (which is not surprising, its "goal" is gene survival, everything else is an accident), and most of those are extremely low level physical things, chemical processes and the like. I'd need to hear some really strong argument that suggested that there's something special about human intelligence that should make us think it's near the limit, otherwise the odds ratio is just too hard to overcome...
But there's no particular reason to believe that the upper limit of intelligence is pretty much right where we are, either.
In fact, I'd argue that based on what we know about other evolved systems, our priors for "the biologically evolved system that does X has plenty of room for improvement" should be much, much, much higher than "the biologically evolved system for X is almost optimal for achieving X".
Like, a thousand to one or more - there are very few tasks that evolution has found optimal solutions to (which is not surprising, its "goal" is gene survival, everything else is an accident), and most of those are extremely low level physical things, chemical processes and the like. I'd need to hear some really strong argument that suggested that there's something special about human intelligence that should make us think it's near the limit, otherwise the odds ratio is just too hard to overcome...