> According to the researchers, the decrease in the size of game and the need to hunt small, swift animals forced humans to display cunning and boldness—an evolutionary process that demanded increased volume of the human brain.
There are plenty of predators that hunt fast small prey, but don't have advanced cognitive capacities. Cats, for example, are adapted to hunting rodents, but have pretty small brains.
> As humans moved into permanent settlements and became farmers, their brain size decreased to its current volume of 1300-1400cc. This happened because, with domesticated plants and animals that don't take flight, there was no more need for the allocation of outstanding cognitive abilities to the task of hunting.
There are active hunter-gatherer societies out there (or at least societies that lean heavily that way along the hunter-farmer axis). Do these societies have larger brains than everyone else? Seems like a simple way to test their hypothesis.