Using newly digitised logbooks detailing the hunting of sperm whales in the north Pacific, the authors discovered that within just a few years, the strike rate of the whalers' harpoons fell by 58%. This simple fact leads to an astonishing conclusion: that information about what was happening to them was being collectively shared among the whales, who made vital changes to their behaviour. As their culture made fatal first contact with ours, they learned quickly from their mistakes. "Sperm whales have a traditional way of reacting to attacks from orca," notes Hal Whitehead, who spoke to the Guardian from his house overlooking the ocean in Dalhousie, Nova Scotia, where he teaches. Before humans, orca were their only predators, against whom sperm whales form defensive circles, their powerful tails held outwards to keep their assailants at bay. But such techniques "just made it easier for the whalers to slaughter them", says Whitehead.