p-ter has the details. For me one of the most confusing aspects of the Hobbits were the concomitant phenomena of extremely small cranial capacities (inference: low intelligence) with relatively advanced toolkits. If it the Hobbits exhibited the pathology reported in the paper which p-ter discusses that might be the solution.
Isn't there additional evidence such as wristbone structure that indicates reasons why the flores specimen may be a distinct species? I think there was another expidition to the cave last year so I look forward to hearing more details about this topic if they ave found anything new (there was a report I read recently that a caver had discovered a shaft at the back of the cave that might lead to a subsection with additional bones).
Interesting, but it still leaves the question whether the individuals found were "pathological" or if the Flores population had evolved so that this gene was the normal one.
The wristbones are definitely primitive and the brain structure basically Homo erectus with extra development in the "foresight" area of the brain. I'm really leaning towards the separate species hypothesis. What's so surprising about island populations differentiating into dofferent species?