The invention of the wheel

Fascinating story (via Hacker News) about the invention of the wheel. It seems like the wheel was invented once and then rolled out (ha ha) across the world. So, the question is: why didn’t advanced civilizations like the Inca’s figure out how to make one? I mean, it’s… a wheel! It seems to be such an obvious innovation to make.
Technological progress of early mankind fascinates me because of two reasons.
First, the speed of innovation is so much slower than today. We’re talking generations, perhaps even thousands of years between each major innovation.
Second, the slow speed of innovation means that the cultural impact of technology is more obvious. Technology changes society and our culture. Things are moving so fast these days that we’re almost speed blind but looking back at history we can see how major innovations like agriculture or roads transformed society.
So why didn’t the Inca’s invent the wheel? I think they were simply too occupied trying to tame llamas or slaves.
In other words, a classic case of innovators dilemma.