So said the Hittites when the Sea Peoples swept in from the seas in the West and the Kaskians surged down from the mountains in the East. So said the Romans wh

So said the Hittites when the Sea Peoples swept in from the seas in the West and the Kaskians surged down from the mountains in the East. So said the Romans when the Teutons migrated their men, women, and children into Italy and took town after town. So said the Sasanians when the Mohamaddans swept up from their deserts with swords and zealotry. So said the Native Americans when the white man brought more and more of his kin to North America. The Romans averted demographic destruction because they acted before the migrants achieved a sure enough foothold. The Hittites were the mightiest people on Earth at the time (they were the first to work iron). The migrants they took in, first thinking they would prove useful as mercenaries to fight their enemies, destroyed them. The Sasanians ruled the powerful Persian empire. A bunch of fanatical desert nomads relying on brutal Assyrian war strategies wiped them out. Native Americans controlled an entire hemisphere, but ended up all but wiped out of the upper half of that. They had centuries to get rid of their migrants, but instead remained fractured, with parts of them allied with the migrants and others against them. The most racially diverse nations do go to war with outsiders less; yet, they are also the ones with the most internal crime, distrust, suffering, and injustice. India's Untouchables, South Africa's Apartheid (followed by South Africa's through-the-roof black-on-white rapes and murders after the ending of Apartheid), Rhodesia/Zimbabwe, Germans and Jews in Germany. If you'd prefer science over history, here are 24 studies in Europe, America, and other places on the effects of ethnic and cultural diversity on group cohesion, trust, strife, civility, and harmony: http://www.truthjustice.net/politics/diversity-proximity-war-the-reference-list/ http://www.truthjustice.net/politics/diversity-proximity-war... It would be nice if we could all just join hands and get along. Unfortunately, humans compete for resources, and cooperate with each other for those resources against other groups. One of the primary ways we divide ourselves is by relatedness (the selfish gene). The more homogeneous the society, the more it trusts and cooperates; the less homogeneous the society, the more it distrusts and divides.