What fun! I can't speak to the animal history/biology stuff. His question about how many actors make a (competitive) market is a central one in microeconomics and in game theory. Microeconomics deals with the advantages of perfect competition (typically thought to require large numbers of buyers and sellers) and the welfare losses associated with monopoly and oligopoly (markets with small numbers of producers). Game theory asks how individuals (including businesses) interact and under what conditions they can maintain collusion (which is anti-competitive). (In certain cases, the number of actors matters.)
So, how about a Microeconomics textbook used on amazon? A game theory textbook? I don't teach econ, so perhaps someone will chime in with a better idea.
