Guns, germs, and steel video

how many species are native to Australia, sub sahara Africa, North and South America combined?

At the time of colonization, the Europeans had a food production system in place that produced enough surplus to allow large parts of their society to engage in other activities, including war. They had better technology such as steel weapons and horses, a writing system that allowed them to share knowledge across generations and finally, over time they had developed immunity to diseases such as smallpox that they took with them to the New World.