It hasn't aged as well as you might like, and it certainly isn't very scientifically sound, but this early novel by Anderson still has much readability and remains a good showcase for his then-burgeoning storytelling chops. What flaws it has are not necessarily Anderson's fault. It feels like a potential SF epic bursting at its 164-page seams. Unfortunately, SF publishing in the Ike era was not quite as receptive to longer novels as it is today. So Brain Wave's brevity can in all likelihood be attributed to editorial requirements of the time that shackled SF writers' imaginations to guidelines dictated by the marketplace. I know I've come down often on novels for being overlong. But there are holes in this tale that would undoubtedly have been paved over smoothly had Anderson been able to expand his story more fully.
The premise is that the Earth has, since the Cretaceous era, been drifting through a sort of force field emanating from deep space that has served to slow down electrochemical and electromagnetic processes. When the planet emerges from this field one day, everything, particularly human and animal brains, start getting better, smarter, faster. Already brilliant men are supergeniuses overnight, while morons achieve levels of intelligence formerly deemed normal. Even the animals get wise: livestock refuse to remain beasts of burden, and the smartest animals, such as chimpanzees, even pick up rudimentary speech. But sociologically, the ramifications of what you might initially think is the best thing to happen to us become devastating. Panic and riots ensue. No one wants to hold menial jobs any more. Citizens formerly cowed by oppressive governments confidently revolt. People have gotten more intelligent, but not necessarily smarter; old prejudices and superstitions continue to hold sway.
This is all good solid speculative fiction, and I was interested all the way through. Yet the book does feel somewhat rushed, as well as heavily edited, and I felt there was more Anderson was wanting to tell me. Anderson focuses his plot on a handful of lead characters, but one — scientist Peter Corinth — gets far more play than Archie Brock, the gentle halfwit living out on a farm who finds himself now mentally competent, but in a world that still doesn't want him. Brock's tale has the heart that Corinth's more cerebral tale lacks, yet I suppose Corinth as a scientist was of greater interest to Anderson's editor back in the day.
So, Brain Wave, while a good book, fails to rise to its ultimate potential — yet for devoted fans of Anderson, it ought not to be missed.