I'm enamoured with Matt Ridley's exposition, but consider an alternative:
-- It takes Og 3 hours to catch a fish and would take 4 hours for him to gather some fruit,
-- While it only takes Iga 1 hour to catch a fish, and 2 hours to gather some fruit
Q1: Who has a comparative advantage in fish, who has a comparative advantage in fruit?
Q2: Are there any gains from trade?
Q3: Does this example disprove the Ricardian model?