As for the claim that agriculture encouraged the flowering of art by providing us with leisure time, modern hunter-gatherers have at least as much free time as do farmers.
I think this is actually true, in a weird way. We work, including commuting, personal errands, and house chores, about 2700 hours per year. Most pre-agrarian people did not work as many hours. Their "work" was a lot more dangerous (throwing spears at angry, large animals) and probably more intense. The stakes were also a lot higher: if they fail, they die. That said, they probably only worked about 1600-2400 hours per year because there wasn't all that much work for them to do. During the off-season (hunting-wise) and during the winter (for gatherers) it's also likely that they slept 10-18 hours per day due to low metabolism/semi-hibernation. (Many medieval people in the Alps went into semi-hibernation in the winter, sleeping 16-20 hours per day.) Whether this is to be considered "free time" is uncertain and probably somewhat subjective. It's unclear what they did. It's likely that their lives were very boring by our standards, exciting only on account of the extreme danger.
AFAIK, in hunter-gatherer sopcities people are divided into two groups: those that can hunt and those who cannot, the latter group including elderly, children, women, and very few other people, e.g. the shaman (this also disproves his point about gender equality, in such socities women are, by necessity, second class). So, it is very hard, esp. for men, to specialize in anything other than hunting, e.g. arts or crafts, unless it brings an immediate utility to the tribe.
Another point is: more people = more brain diversity -> easier for people with interesting ideas to be in the society, the intellectual gene pool, if you will. And an agri lifestyle definitely supports larger tribes.
> in such socities women are, by necessity, second class
Not necessarily. Please take into account that in all but most extreme climates, most of the raw calories in a hunter-gatherer group comes from the gathering part, which is mostly a female activity. The problem with a pure gathering diet is that it tends to be protein and fat deficient, so one strategic contribution of the male hunters is not to keep the bellies full, but the diet balanced. Neolithic farmers discovered the hard way that a belly full of grains still leads you to malnutrition.
The other big strategic contribution of male hunters to their communities is protection. The only way a bunch slow moving, child bearing women can wander safely in the wilderness gathering food and wood is to bring a couple of armed men along. This men were probably too old or too young to join the hunters, but would provide a valuable service in protecting their people of predators (human or otherwise).
Not to imply that women are unable to defend themselves... but Nature does not care about political correctness. Females are more valuable to the reproductive capacity of the tribe, so it makes more sense to have males run higher risks.
I think this is actually true, in a weird way. We work, including commuting, personal errands, and house chores, about 2700 hours per year. Most pre-agrarian people did not work as many hours. Their "work" was a lot more dangerous (throwing spears at angry, large animals) and probably more intense. The stakes were also a lot higher: if they fail, they die. That said, they probably only worked about 1600-2400 hours per year because there wasn't all that much work for them to do. During the off-season (hunting-wise) and during the winter (for gatherers) it's also likely that they slept 10-18 hours per day due to low metabolism/semi-hibernation. (Many medieval people in the Alps went into semi-hibernation in the winter, sleeping 16-20 hours per day.) Whether this is to be considered "free time" is uncertain and probably somewhat subjective. It's unclear what they did. It's likely that their lives were very boring by our standards, exciting only on account of the extreme danger.