Are humans getting cleverer?
bbc.com
bbc.com
What? That head man of the Siberian tribe gave a darned excellent answer there.
There is nothing scientific about taking the premises for granted that bears are always white wherever there is always snow, and that there is always snow at the North Pole. Unless you empirically investigate these things for yourself, you take them on authority. Deduction isn't scientific; it's just a way of rearranging logical statements to see their truth value in a different representation.
From the premises it can be deduced "bears are white at the North Pole", but that doesn't make the premises true.
The Siberian simply didn't recognize the academic context of being asked a question about logical deduction in order to demonstrate that he understands that form; he looked at it in a broad, real-world context relevant to himself and his position in that world.
It could be said that even people (not logicians), who answer that bears there are white, are not using a logic system including the Modus Ponens, because they would also stand that there are darker bears at the North pole, teddy bears, and that even white bears are not entirely white.
So indeed, it's hard to judge this Siberian intelligence, without further elaboration.
There's a problem of selection, and the system that sets the selection criteria is as important as the population selected. Perhaps the IQ only measures the match between the selection criteria and the population. Raising it or lowering it is caused as much by changes in the population, as changes in the selecting system.
If everyone did nothing but check everyone else's results, there would be no progress. While we don't trust first-hand original research, we do place trust in third party validations of research.
And the ending idea of there being more geniuses, just that they're unrecognized--are they? We've been accumulating knowledge for a long time. Sure, in the 1500s there were people who were top of the class in physics, chemistry, and biology. I'm sure many, many people here know (or could readily learn) those as well as the great polymaths, and come up with novel new-to-the-1500s-models ideas. But physics, for one, has gone so far beyond what we understood back then.
You're impressed by people inventing calculus? Yeah, it's pretty impressive. It's also something a fairly intelligent person these days can at least _understand_ as a young teen. Do you have any idea what we've developed to model modern theoretical physics?
Another possible explanation is immigration, which selects for people that can do paperwork really well; at least in America.
But the average score of IQ is 100 by definition. It doesn't matter whether the test is hard or easy, since the score system is determined by the average performance of people on the test. So even if a test was nearly impossible and nobody got more than 2-3 questions right, the average result would still be 100, because the points would be computed accordingly.