War: is it in our genes?
Capitalism drives modern warfare — but our species has waged determined and passionate campaigns of murder against each other long before its arrival. How can we begin to explain this, asks JOHN GREEN

AT this moment armed conflicts are taking place on all continents apart from North America and Antarctica. We live in a world in which war has become an accepted fact of life.
Homo sapiens is the only species on the planet that deliberately kills its own in huge numbers —and with the grisliest cruelty. All other animals may battle over territory or to obtain a mate, but they rarely kill; their battles are more ritualistic, simply driving the vanquished away.
They are satisfied with the territory or the mate they have or the food they have gathered, they are not driven to want excess. On the other hand, humans are driven invariably by greed and go to war for more land, food, and wealth than they need. Why?
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