&gt;<i>Aren&#x27;t there lots of low hanging fruit that we haven&#x27;t taken yet? It seems like it&#x27;d be easier to eliminate the things that are known to cause decreases in intelligence, first. Or, do we not know what those are?</i><p>Yes, these issues have been researched, and are continually being addressed (though one might argue they should be given much more attention than is currently the case).  Some examples of causes of decreased intelligence include malnutrition (sometimes caused by parasites), and heavy metal poisoning (often lead and&#x2F;or arsenic in well-water).[1][2][3]<p>&gt;<i>Also, having been around a lot of &#x27;highly intelligent&#x27; people, I have found that many are still not very effective. Most still make bad choices, have poor judgement, adhere to dogma, can&#x27;t think laterally or fluidly, lack curiosity, lack discipline, etc. Is it possible for a &#x27;smart&#x27; individual to get better at those things?</i><p>If you are interested in these issues, I suggest that you read some of Phillip Tetlock&#x27;s work on judgement and prediction; I have found it tremendously interesting and helpful, though I have often been taken aback when re-examining my own faults through the lens of his work.[4]  From what I have read, you are already at a tremendous intellectual advantage, as you are examining meta-cognition issues, which can help you improve your cognition, and understand your limitations.<p>[1] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Impact_of_health_on_intelligence" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Impact_of_health_on_intelligen...</a><p>[2] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Lead_poisoning" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Lead_poisoning</a><p>[3] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Arsenic_poisoning" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Arsenic_poisoning</a><p>[4] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Philip_E._Tetlock" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Philip_E._Tetlock</a>