older SF, earth moves into a cosmic space which reduces human intelligence

I'm actually struggling to remember two old SF stories that involve the premise that earth's location in the cosmos has a direct effect on humanity. The planet passes into a zone or a cloud which changes the working of our brains.

One explores the consequences of a general loss of intelligence across the board. And I can't even remember the viewpoint or the resolution.

The other one notches down human tolerance for irritation and reduces inhibitions, which results in unprecedented aggression. Violent crime becomes normalized.

I'm possibly conflating the back stories as to the cause of the change.

I'd like to explore this trope of cosmic effects on humanity, so other titles would be welcome as well.

Brain Wave by Poul Anderson has every person and animal on Earth getting smarter practically overnight as the solar system moves out of a region in space where intelligence is muffled.

That's it! Gee, I must still be in that muffled space to have gotten it so backward.

And, yeah, the increased animal intelligence created some interesting moral dillemas.

If you are interested in that kind of concept, there is something similar in A fire upon the deep by Vernor Vinge. To me, this books is reminiscent of old-fashioned sf with too much emphasis on concepts and not enough on character and story, but I have to admit, the concepts in this book are pretty cool. Part of it involves regions in space that inhibit technological advancement. Or something like that, I don't remember the details.

Brain Wave was my first thought, too. Something in the other direction would be the short story "The Locusts" by Larry Niven and Steve Barnes. Not sure what Niven collection it's in, though.

Your other query doesn't ring any bells with me. Fritz Leiber occasionally had some stories where violence was fairly normalized, but it wasn't the result of a cosmic event, just basic societal trends.

Are you sure this is SF? Sounds more like a documentary of current events to me.

Yup, Anderson's Brain Wave. IIRC, it includes this tidbit: the last time Earth was passing through that high-intelligence field ended 65 million years ago, causing some nasty extinctions. One of the protagonists, an 11yo boy, figures out integrals over lunch while doing his math homework. Normal-intelligence people become extreme geniuses, while special needs people are merely bumped up to the level of what we would consider geniuses, meaning that even with this boost in intelligence they're doomed to remain special needs people.

S.

For a book that touches on this topic, read Bimbos of the Death Sun it's really funny
The main character wrote a somewhat scholarly book on this subject and his publisher renames it Bimbos and markets it at a sci-fi convention where all kinds of shenanigans happen.