Winner of the 1998 Pulitzer, Guns, Germs, and Steel attempts to answer why human history unfolded differently on different continents. Drawing on evidence from a diverse range of disciplines, Diamond argues that the varying rates of human development over the past 13,000 years have had little to do with genetic superiority. Rather, they are due to differences in environment: in plants, animal species that could be domesticated, the sizes of areas and populations, and the advent—or lack of—agriculture. Agricultural societies could diversify and develop technologies; people were able to become warriors, leaders, and tool-makers, leading to a virtuous circle of technological advances.