Eurasia ended up with the most domesticated animal species in part because it's the world's largest land mass and offered the most wild species to begin with.

F. 2005 Collapse: How Societies Choose to Fail or Succeed. PMID 3762700.

Originally trained in physiology Diamond's work is known for drawing from a variety of fields including anthropology ecology geography and evolutionary biology. He is currently Professor of Geography at the University of California Los Angeles.