I'm looking for a word whose definition is something along the lines of "growing in intelligence". I'm trying to use it in a sentence like "the people are getting smarter and smarter throughout the years".
I'm not sure that there is a single word that means specifically what you are looking for, at least not one common enough that you could expect your readers to know it. Stick enough Latin stems together and I'm sure you could make something up.
There are words that could be interpreted to mean such a thing in the right context, such as 'evolving', which was previously suggested. Others have suggested phrases, and there are plenty of those.
Some suggestions to fill in the blank below follow:
"People are ____ over the years"
- smartening up
- wising up
- wisening up
- becoming more intelligent
- gaining intelligence
- improving intellectually
- improving in intelligence
- growing intellectually
- and so on...
I would probably use 'becoming more intelligent', but 'growing' might highlight that the change is an increase better than 'becoming', although both would have 'more' included in the phrase.
That being said, if you're talking about a change in the makeup of the population as new people are born and die, rather than highlighting the intellectual growth of individuals within the population, you might want to rephrase things to make that clearer. In other words, no one's intelligence is changing, instead the makeup of the population is changing.
Something like gaining wisdom? Cognitive development is usually applied to the mental development of children as they grow up. Intellectual development is more often applied to adults during their lifetime.
I'm not sure there is a need for such a word to apply the general populace, although from GPAs, you might think so.
If intelligence is one of the primary defining characteristics of our species, you might say evolving
to change or develop slowly often into a better, more complex, or more advanced state : to develop by a process of evolution
If the implication is that people were not insightful, but are becoming more so, you could say wising up
(slang) to make or become informed, insightful, etc.