Pffffthahahaha. This has a grain of truth; prior to 12,000 years ago there was very little movement between continents. There was very little agriculture, and humanity was mostly small tribes and nomadic. "Egalitarian" is a hell of a stretch though; the only theories we've come up with that explain our brain development is internal conflict; human vs human, and not merely between tribes but jockeying for position inside tribes. Whether a tribe had one head man or a group of "elders" is a good question; circumstances may have switched back and forth over time. When agriculture became prevalent things changed enormously. Permanent settlements sprang up, which had to be defended and which allowed for stable infrastructure, and the increase in available food was able to support armies. Tribes became larger and began exploiting each other, and kingdoms sprang up. But it took more technological improvement over a few more thousand years before most people even had a chance to "visit foreign lands, meet interesting people, and kill them." Edit: And I completely lost my train regarding slavery. Tribes would often capture people during inter-tribal conflict and enslave them or take them as concubines, even before agriculture.