I'm kind of late posting here, but I wanted to let every one in on some research that has been taking place with brain size and autism. I can only find reference to one study in 2005, but I know I just read another study which confirmed the correlation.
Here is the 2005 article:
http://www.myomancy.com/2005/12/autism_mercury_Like twomoose said, I've read it has more to do with making associations between the two hemispheres, and possibly the number of folds or wrinkles in a brain that determines intelligences.
The question isn't how big is the brain, but how big is the primary work it does to keep it alive. Whales or elephants require larger brains, because they are larger animals. The ratio of that brain to their body requires a lot of primary cortex use, directly using the brain to help move their muscles and sensory uses. Human brains have primary cortex, but we have a secondary and tertiary cortex that allows for additional processing....
We have a lot of brain matter that can't be explained by moving a muscle or sensory issues...Anyway, I don't know if this makes sense, but I just thought I'd add why brain size doesn't really relate to intelligence.
