It's startling to come back to a book you read when you were 9 and discover that it has some eerily prescient science-fiction concepts. I don't know if this book could be published today, but if you can find a copy it's well worth a read.
I read this book repeatedly when I was 9 or 10 - it was the only science fiction book my grandmother had in the house, and whenever I stayed with her I would read it. I know I read it sometime around when I read Clan of the Cave Bear, because when I finally figured out what this book was (thanks, Ask Metafilter!), found it (thanks, Borderlands!) and read it again, I realized I had conflated some of the details of the two books in my mind.
[Side note: The strangest thing about the copy I found is that the handwriting on the back page is identical to my grandmother's, but I found it in a used bookstore over 3,100 miles away from where she'd lived.]
There are some ways in which the books are similar. Like Ayla, Daiya is a misfit in her village (although she is not born of a different species), with radical ideas that her tradition-bound elders reject. Like Ayla, Daiya has to go through a rite of passage to be accepted as an adult in her village. If you read the two back-to-back, you could see how a 10-year-old could conflate certain aspects.
Even if there are certain character and structural similarities, Watchstar is a very different books, and one that deals with concepts which seem to me to be as relevant today as they were 30 years ago. The book takes place post-technological singularity, and over the course of the novel Pamela Sargent shows several different potential paths for a post-technological society.
If it seems like I'm giving away a lot below, this is all in the first 30 or 40 pages. Sargent does a good job of painting the society, although I can't help but think that under a modern editor this book would have been 200 pages longer and had a lot more detail about the society in questions.
The society that has evolved is telepathic and telekinetic, agrarian and insular, with low population density. Adults communicate with each other exclusively by telepathy, can heal themselves with their psychic powers, can fly and lift objects and much more. However, all of this is treated in the book the same way walking or using a tool would be treated - it's just the way life is. There is no written language; knowledge is passed on through the Net, the psychic collective that everyone is a part of. People live in nuclear family units with many children, the children move out and start their own families, and once the parents become empty nesters, they enter the next phase of their evolution. Their selves begin to merge with this collective consciousness until they become completely one with everyone. Sounds like Glen Beck's worst nightmare of collectivism, right?
Oh, yeah, and the old and most enlightened people also have a lot of group sex - a way in which this book is very '70s. Another way this book is very '70s, which I appreciated, is that our heroine is not white, nor are the majority of the people in her village. They're a United Colors of Benetton mixture, which seems like it would fade after 2,000+ years of interbreeding, but I digress.
Some infants are born without this psychic ability; they're called solitaries. The solitaries are considered non-people and are euthanized shortly after their birth. For them to live would destroy the harmony of the village, say the elders. Objections to this or anything else rarely come up - to object to tradition, or to have a different idea, or to be alone, is to destroy what is harmonious about society.
Daiya is taught that her people once lived in a technological world. Then a miracle happened and people were able to communicate psychically. She's taught that many lost their minds and tore themselves apart or tormented those who could not communicate psychically. Finally, she's told, the enlightened psychics destroyed everyone who wasn't them, leveled the city and split off into small villages in order to preserve humanity.
This is science fiction - so of course you know a twist to that is coming.
Daiya goes into the desert to prepare for her ordeal, unnerved by the comet that has been hanging in the sky. She sees something odd, and investigates. She finds a young man who has come down from the sky in a shuttle to investigate her world. He lives on the comet, his people originally came from Earth, and their post-singularity evolution has been very different. And - oh yeah - he's a solitary.
I was surprised to realize that Daiya is 14 and the spaceboy she meets is 16; in my memory they were both adults. Not sure if you could do that today considering some of what happens to both of them.
Though some of the set decoration that surrounds the people in these two societies are a little on the '70s side, many of the concepts are very up to date and forward thinking. This book in general doesn't feel dated to me like many other science fiction books I read do (such as the earlier Darkover books, for example).
I didn't realize it when I was a kid, but this is the first book of a trilogy. Now I need to find the other two!