Earlier quoted context omitted.
IQ tests are proxies for intelegence but not direct measurements. They are fairly good at that from around 60-140, and less useful at the top and bottom. As to low IQ scores people with an IQ of 60 generally don't have anything that they preform very well. The problem is everything we think of as takes even something as simple as holding your hand steady is really complicated. Getting better at even simple motor func…
An IQ of 60 isn't difference, it's indicative of either malnutrition, severe neglect, or some form of developmental disorder. In fact, I'd be surprised if there are many people of below average intelligence that don't suffer from one of those things. I'd even wager that if you took any random infant that didn't have a developmental problem and raised them in a loving affluent western family with good food and an enri…
Further sub 110 IQ's don't indicate a problem. Natural variation is simply much wider than you assume.