It still does not make sense. Humans were in a hunter-gathering mode for quite some time. If they were so much healthier, AND had more free time, why did the society start rapidly progressing only with the advent of agriculture? Did they just magically become smart? I'm sorry, but no. While this article is certainly interesting, and thought provoking, the thesis doesn't hold.
They didn't suddenly become smart and you certainly cannot attribute all the developments to the adoption of agriculture. Progress has been very... erratic (can't find the right word) throughout history.
To blindly attribute progress to a singular cause such as farming is short sighted. I'm sure there are many different variables (farming included) that influence progress and discovery.
Agriculture is not exactly the reason for technological advances; rather, progress became possible (but not guaranteed!) thanks to agriculture.
While a few hunter-gatherer societies lived in a place so abundant that they can settle in a single location and gather everything they needed, the vast majority of such societies were migratory, moving to wherever the food was.
In a migratory society, most technological advances are simply not useful. When you only keep the things you can carry on your back, anything that doesn't have a direct use is an active hindrance with a quantifiable opportunity cost. Civilization is only possible when people can settle in one place.
Further, even hunter-gatherer societies that are fortunate enough to settle in a single place have to remain small to survive, or they exceed their food supply. This means that the chance of a given society developing a new technology is much smaller (given a smaller supply of creative individuals). It also means that even if a society does develop a new technology, that technology spreads very slowly, leading to less cross-pollination with other individuals and ideas.
By contrast, agriculture concentrates people together. There are a variety of technologies that increased the productivity of an agricultural society as a whole, and it's very natural for those technologies to spread throughout a society. Furthermore, agricultural societies that are more productive than their neighbors can produce more soldiers (when a smaller percentage of the population can feed the whole society, there is excess labor for armies, as well as other pursuits), allowing them to conquer their neighbors and spread their advances to their newly conquered territories. Basically, in an agricultural society, technology spreads like a virus.
