Spontaneous Generation

No, I'm not talking about the children of the 60's, you silly people.  It's what we all heard about in seventh grade science class, laughed about with an air of superiority, and pushed to the back of our minds with all of the other trivia that holds no bearing on modern life.  Today, the idea that organic life can spring from non-living matter, like rats born from a pile of rags, maggots from rotting flesh, or policemen from a sack full of hammers (I'm not sure about that last one) is laughable to everyone.  The reason to discuss it is simple: we didn't get around to fully disproving it until the 19th Century; thank you Louis Pasteur.  Consequently,  characters in a Fantasy setting might just hold with this belief.
    Much like the whole "the Sun goes around the Earth" concept (though the Church held on to that longer than common people did),  the idea that something can come from nothing was a widely held belief.  In a world ignorant of the microscopic, and with limited capacity for the scientific, it is an entirely understandable conclusion.  This concept is also in line with any belief in a Creator/God.  If a god created life once, no reason not to do it again, or all the time.  
    Modern scientific thought doesn't even have a good answer for where life came from originally.  It's entirely possible that life may spring from inanimate matter on a microscopic level.  You can't prove that it never does.  Science doesn't work that way.  Bigger stuff, though, is pretty clearly a no go on the spontaneous generation front.  Eventually we learned that flies lay their eggs on rotting flesh (which become maggots), and microorganisms can travel through the air to make your food moldy.  However, it took a long time for scientists to devise the proper experiments to disprove these theories.   
    Is it such a difficult concept to believe?  Weren't humans made from clay before being brought to life (at least in Greek myth)?  It's only natural then  for your characters to believe that elves were birthed from the trees and dwarfs from stone.  I seem to remember orcs having been birthed from fungi in some universe.  When you remember to remove some of our ingrained scientific understanding, you leave a lot more room for magic and wonder in your world.  Give it a try and you just might give birth to something wholly new.  




http://www.accessexcellence.org/RC/AB/BC/Spontaneous_Generation.php
http://www.allaboutscience.org/what-is-spontaneous-generation-faq.htm


interestingly, the second site seems to be going in an anti-evolution direction with some of its entries.  the history part seems good though.  as always, be mindful of what you read.