I enjoy reading a good epic fantasy from time to time. Sure, it's a well-worn genre, but I like a big story, and if it's well-written, it can be fun.
I just finished re-reading Tad Williams' Memory, Sorrow, and Thorn trilogy (for the first time since it was published 20 years ago). It was enjoyable, despite a bunch of cliche bits.
But it got me thinking about how ridiculous many fantasy worlds are when you look a little deeper.
The first example is the Sitha (Tad Williams' elves). In these books, the Sitha are immortal, and it's stated that they give birth approximately every 500 years. They migrated to the continent they're on thousands of years ago, but it doesn't say how many. For some reason, their population is ridiculously small, but that really doesn't make much sense, especially considering that they were the unchallenged rulers of that continent for a long time.
If we assume that 1,000 Sitha were in the first migration, and that migration occurred 10,000 years ago, how many Sitha should there be "now"? Let's assume that the every 500 years birth pattern is true. Let's also assume, since they're immortal, that the females can continue to have children indefinitely. That means that every 500 years, half of the population will give birth to a child, of whom half will be female, and so on and so forth.
In other words, every 500 years the population should increase by 50 percent. After 10,000 years, the initial population of 1,000 should be over 3,000,000 (that's 3 million)! That's a lot of Sitha! In the books, however, they're a dying race. Yes, there's been a bunch of wars and such, but those wars started a long time after their initial migration, when their population should already have been in the hundreds of thousands.
The other goofy bit of ecology is a dragon that supposedly lived in a system of tunnels underneath a castle. The dragon is described as being very large, presumably bigger than an elephant. While there are some big spaces in the tunnel system, there's no giant pathway into the part where the dragon is, which seems to be pretty far into the tunnel system. Maybe it was born there and grew too big to leave? I can buy that, but what does it eat?
People know about this dragon, so excluding the occasional foolhardy hero, I don't think there's a lot of traffic down there. Certainly there is probably nothing bigger than mice and bats, and even they would probably avoid a large predator's living space.
Stuff like this does kind of annoy me, because it seems like the author adopts some fantasy convention (immortal elves who are dying out) without actually figuring out how to make that make any sort of sense, other than "it's a magic world, and I say so".
A good example of doing better is Robin Hobb's Elderlings trilogy of trilogies. She actually comes up with a very interesting and sane life-cycle for various fantastic creatures (I don't want to be too specific), and even includes things like natural disasters in this fantasy ecology. It all makes sense and ties into the story very nicely.
