In short

Jared Diamond convincingly argues that geographical and environmental factors shaped the modern world. Societies that had a head start in food production advanced beyond the hunter-gatherer stage, and then developed writing, technology, government, and organized religion—as well as nasty germs and potent weapons of war—and adventured on sea and land to conquer and decimate preliterate cultures. A major advance in our understanding of human societies, Guns, Germs, and Steel chronicles the way that the modern world came to be and stunningly dismantles racially based theories of human history.

My takeaways

Why did Europeans conquer the Americas and not vice-versa? Spoiler alert: It has nothing to do with race or intelligence of the Europeans.