When the Lusitania was torpedoed by a German U-boat in 1915, it sank in 18 minutes and the bulk of survivors were young men and women who responded immediately to their powerful survival instincts.

But when the Titanic struck an iceberg in 1912, it took three hours to go down, allowing time for more civilized instincts to take control. — and the bulk of the survivors were women, children and people with young children.

Economist Benno Torgler of the Queensland University of Technology in Australia and his colleagues studied the two sinkings in order to explore the economic theory that people generally behave in a rational and selfish manner. The two tragedies provided a “natural experiment” for testing the idea, because the passengers on the two ships were quite similar in terms of gender and wealth.

The primary difference was how long it took the ships to sink.