The hunter-gatherers did not necessarily chose a farming lifestyle, they were likely displaced by the sheer numbers of the farmers. However, modern agriculture requires very few people (proportionally), under 5%. The second worst mistake in human history would be to stifle agricultural and industrial development. There is the great opportunity to lift the other 2/3 of the world out of "farm slavery". Not only to just feed them, but raise their standard of living too.
You could interpret a pre-industrial economy as working on a flat per-capita capital increase. People grew as fast as capital, so there was little opportunity for accumulation (outside the very small ruling class). That is no longer the case, although there are powerful ideologies that would undo it.
I'm not sure the point is to stifle industrial development as much as it's to show we've built our society on several "facts" that might not be entirely accurate. Further I think the author is trying to say people in our society don't question these supposed facts and that society is worse off because of it.
In this case his point is that modern society takes hunter/gatherer cultures that still exist and tries to change them to agriculture based cultures without questioning whether it's best for them.
In your very reply you proved the second point. Let me lay it out...
- His central argument is against the assumption that agriculture is proven to be better than hunting and gathering. He showed evidence of hunter/gatherers spending less time acquiring food and getting a better balanced diet in spite of that.
- You replied that agriculture is great without giving any evidence to refute his argument. The fact that modern agriculture requires fewer people than it once did is only relevant to his point if you have numbers that say modern agriculture's time to acquire food has fallen below that of hunter/gatherers. Otherwise it's irrelevant. Plus you didn't even address the balanced diet argument.
So you've proven the author's main point in that you fell back on the assumption that agriculture automatically equals the best solution.
The article is based on a false dichotomy. Hunter/gatherers farmed, and farmers hunted and gathered. Some did more hunting and gathering, while others did more farming, but for most early societies the labels "hunter/gatherer" and "farmer" describe the same people. See a fantastic (and fantastically short) book on this by Colin Tudge: http://www.amazon.com/gp/product/0300080247.
Exactly. When farmers outnumber you, guess who's winning any land disputes? Even if land changes hands peacefully, a farmer can give you more food for your land than you could possibly gather on it. As Diamond points out, today's gatherers live on land that's not good for farming.
You could interpret a pre-industrial economy as working on a flat per-capita capital increase. People grew as fast as capital, so there was little opportunity for accumulation (outside the very small ruling class). That is no longer the case, although there are powerful ideologies that would undo it.