Every human being is an unique individual. Thus it surprises me to see humans engage in collective herd-like behaviour. This collective mentality I think is highly destructive and is responsible for a lot of the world's problems.
Every human being is capable of being a psychopath, meaning that we have the capacity to choose the most selfish and least useful path (as in the prisoner's dilemma scenario) even though we're fully aware of the consequences. There is no group, organisation, race, or religion that can claim a monopoly on psychopaths. When individuals do so on behave of a collective, they're only using the collective to their advantage, as an excuse to be a psychopath.
This is by no means exhaustive and are listed in an arbitrary order; group classifications are also generally arbitrary but are based on human conflicts over the centuries. Please send any additions to me. Note that the present tense of the word "kill" is used as though these comments are made by an observer who is watching humanity with the time dimension compressed.
Albanians kill Serbians. American Indians kill Americans. Americans kill Afghanis. Americans kill American Indians. Americans kill Arabs. Americans kill Germans. Americans kill Iraqis. Americans kill Muslims. Americans kill Russians. Arabs kill Americans. Arabs kill Jews. Arabs kill Kurds. Arabs kill Turks. Armenians kill Turks. Basques kill Spaniards. Blacks kill Whites. British kill Africans. British kill American Indians. British kill French. British kill Germans. British kill Indians. British kill Irish. British kill Portugese. British kill Scots. British kill Spanish. Catholics kill Jews. Catholics kill Muslims. Catholics kill Protestants. Chechens kill Russians. Chinese kill Chinese. Chinese kill Indians. Chinese kill Japanese Chinese kill Tibetans. Christians kill Muslims. French kill Indians. Germans kill British. Germans kill French. Germans kill Jews. Germans kill Poles. Germans kill Russians. Greeks kill Turks. Hindus kill Muslims. Hutus kill Tutsis. Indians kill Chinese. Indians kill Pakistanis. Iranians kill Iraqis. Iranians kill Kurds. Iraqis call Iranians. Iraqis kill Kurds. Iraqis kill Kuwaitis. Irish kill British. Israelis kill Palestinians. Japanese kill Chinese. Japanese kill Koreans. Japanese kill Russians. Jews kill Arabs. Jews kill Romans. Kurds kill Arabs. Kurds kill Armenians. Kurds kill Iranians. Kurds kill Iraqis. Kurds kill Turks. Kuwaitis kill Iraqis. Muslims kill Americans. Muslims kill Christians. Muslims kill Hindus. Normans killed Saxons. Pakistanis kill Indians. Palestinians kill Israels. Protestants kill Catholics. Romans kill Christians. Romans kill Germans. Romans kill Jews. Russians kill Americans. Russians kill Chechens. Russians kill Japanese. Saxons kill Normans. Scots kill Brits. Serbians kill Albanians. Spaniards kill Basques. Spanish kill Incas. Spanish kill Mayans. Spanish kill Muslims. Sudanese kill Chadanese. Sunnis kill Shiites. Turks kill Arabs. Turks kill Armenians. Turks kill Greeks. Turks kill Kurds. Tutsis kill Hutus. Vikings kill British. Vikings kill French. Vikings kill Irish. Vikings kill Scots. Whites kill Blacks.