From Andy Turnbull:

Re: More unequal societies spread faster, according to simulations (Sept. 28): Could be, but there's another possibility. I suggest that perhaps societies are unequal and they spread faster for the same reason -- that the ruling class is rapacious. I would not suggest that invasions of other countries are led by the poor -- rather that they are led, or ordered, by the wealthy.

Andy Turnbull
Toronto, Ontario
Canada