It is not surprising to me. At a certain point "intelligence" becomes a hindrance to evolution. It could be a speed bump or a cul-de-sac, which is determined by how we handle it.
It is possible that there are multiple phases in how evolution is affected by intelligence.
1/ Intelligence selected for as an advantage.
2/ Knowledge at a plateau where it (intelligence) is advantageous but higher IQ not enough to be selected for
3/ Medicine & Society advanced enough to keep alive those who would have been selected against (now)
4/ Biological science advances to the point of directed evolution (whether by a plan or just "fashion") (approaching)
For some time now, large segments of our populations have not been subject to natural selection, only sexual selection. The result is predictable.
Just wait until we all evolve peacocks tails. Then you'll have something to complain about.
Actually with plastic surgery and so on even this is being neutralized.
Damn you Nemesis. (That's a good damn you...) Picking this stuff apart is what makes me want to continue.
On the topic of intelligence I suspect that intelligence is partly nurture, that most people have the potential if they had been nurtured differently to have higher IQs. This could explain for example the various sudden surges in knowledge in prehistory as society changed and the way of nurturing children raised the IQ of future generations. These "primordial" jumps could easily be partly improved nourishment rather than how the young were cared for.
Now apply this nurture idea to earlier hominids. One genius comes along and invents the stone axe. Merely by inventing it and passing the knowledge on he changes the way the young are raised. They spend part of their youth learning the best and easiest means of making stone tools, actively developing their ability to think in at least one way. Physically they are unchanged but their brains are jumped up to a higher level of mentation by training. Later mutations for better hearing or vocalization result in bigger vocabularies and with more words more ability to think and communicate complex thoughts, without changing the brain up jumps the IQ again. Of course a larger brain makes the higher IQ easier for an individual to develop so it would still be selected for. Longer lives would also be selected for as those who lived longer learned more and passed more on to the next generation.
Those with the greater use of their brain had a reproductive advantage. Those who nurtured their children in IQ enhancing ways gave their tribe an advantage. Those whose tribes suppressed the use of thought lost out.
Now apply this to homo floriensis. They had tiny brains but had tool use equal to the larger brained (and possibly their ancestor) homo erectus. That mere tool use might have caused those small brains to be used more thoroughly to the point where though their IQ potential had dropped it still maintained the IQ level to keep their cultural level though perhaps not enough to advance it.
Apply it to Neandertal. They preceded Sapiens but didn't advance as far in culture or technology. It could have been as simple as their rough environment kept them from having time to develop thinking in their kids or had a culture that suppressed "smart asses". It could also be that they didn't have the mutations for vocalization or hearing to allow a large vocabulary or had ones that were not as broad in function. It is a lot harder to think of something you have no words for and they might have need the larger brain to function at an equal or near equal IQ level.
If we were to take a chimp, mutate it with the changes to vocalization and hearing then raise it with humans how smart would it become compared to a wild chimp or a normal chimp raised by humans? Extend its childhood as well to give it more time to learn and again how smart would it be? Of course letting it choose to name itself Caesar might be a bad idea (Trivia question who knows the name given to Caesar in the 3rd Planet of the Apes movie by his mother Zera?)