In order for Crabtree's hypothesis to be true, people in third world countries who have to use traditional skills in order to survive should score higher on intelligence tests than people in developed countries, but that's not the case. To my knowledge, there are two things that can adversely affect people's intelligence quotient: malnutrition and a lack of cognitive stimulation. In the developed world, we have to use our problem solving skills very often, and we certainly don't suffer from malnutrition. Hunter-gatherers, on the other hand, only had to hunt and gather. These are simple activities which do not involve problem solving.
I really like this quote: "Crabtree does argue that no matter how deteriorated our intellectual abilities may have become over the millennia, advancements in technology will someday render these changes insignificant."
If people are getting dumber, who's going to invent these advanced technologies?
Well, I also can't be sure ($40 for anything like this just doesn't seem like a good deal), but I could imagine that one could argue that only a select few are actually responsible for the technological riches of society… while the people who benefit from those riches aren't necessarily capable of reproducing, improving, or even repairing the things around them.
Think about the iPhone for example-- I would imagine that something like that is unthinkably complex to the majority of people who own them. It's not magic, because people still know that it's made of aluminum and circuits and chips and plastic… but I highly doubt that it would be possible for most people to assemble one from scratch, even when given all of the necessary parts and tools.
You say that hunting/gathering isn't intellectually stimulating or demanding-- have you ever been hunting? Even with a semi-automatic rifle and an abundance of non-dangerous game, a lot of people nowadays still find it difficult. So how would one do the same thing with primitive tools, as well as the ever-present threat of being killed? It's kind of funny how we always assume that ancient humans would look at modern humans and say 'that's magic!', when chances are if we actually met a primitive man and saw how they did things, we probably wouldn't believe it either.
Whenever you go into the wild, there are the time-tested things that you need to know how to do, but there are also unexpected things that can occur and require problem-solving abilities to resolve-- otherwise you die. There are a lot of survival situations where you need ti able to recognize beneficial elements simply from what's on hand, and failure to do so can be a matter of life or death… so practically
everyone would have to be innovative-- but in the west, and especially in the cities, people just aren't faced with those kinds of situations.
Some people may be lucky, but most of us work at jobs that are routine and not particularly challenging. Quite a few jobs in the west don't demand
any degree of innovation from the people involved… and certainly aren't physically healthy. We get our food from supermarkets, our entertainment from computers, film and TV, our knowledge from books, newspapers, etc… there really aren't a lot of opportunities for the average person to actually apply or exercise their intelligence.
