> 10 adults for one child? I think I would not want to live in that
> world. Humanity would wither and die.
Eventually, yes. The theory, as I understand it, is to keep to that ratio until reaching some ideal population figure. I get this sort of stuff from green fundies--dear friends, I might add, in many cases--all the time.
A more reasonable version, which one of those dear friends put into a non-unreadable novel, is for each couple to have only one child. That, I think, could be done without wrecking the culture, and might even be something people would be willing to do (assuming they were willing to couple up--a plot point in the novel (which I would mark as a spoiler, except that I'm pretty sure none of you will ever read it--it's locally published and essentially undistributed--involved the protagonist getting someone other than his long-term significant other pregnant). God knows, I can barely handle one child--twins would've probably killed me.
My understanding of the evolutionary psychology explanation of population is that humans have (I think this is right) a k-strategy for raising offspring--one at a time, rather than in batches--and that reducing number of offspring requires giving people reason to believe that their one child or two children will prosper and thrive. Otherwise, people have more kids in order to ensure that at least one of them survives. This turns the k-strategy into a strategy which (I think) was labeled with a Greek letter, where animals raise litters in the hopes of at least one surviving.
What I took away from that was that population stability requires decent living standards for all. Whether I understood correctly or not, I can't really say--but it made sense. I think.