Intel-sharing sperm whales may have taught each other how to avoid harpoons when whalers began hunting them 200 years ago. A new study presents evidence of social learning in the animals and offers a window into a form of whale culture.
The research focused on 19th Century whaler logbooks from the North Pacific, which recorded details of hunts, such as the number of whales spotted or harpooned on a given voyage. Analysis shows that the ships’ strike rate fell by 58 per cent in less than two and half years after the whalers first arrived in the region.
The study, published by the Royal Society, combined the work of cetacean researchers Hal Whitehead and Luke Rendell, and data scientist Tim D Smith. Their analysis concluded that the drop-off could not be attributed to other factors, such as whalers initially targeting vulnerable whales and thereby boosting their numbers.
Instead, they believe that whales came to understand the threat and adapted new escape strategies, such as swimming upwind of the wind-powered ships. This information was then shared in their pods, suggesting rapid social learning, cultural evolution and real-time communication.
Sperm whales, which have the largest brains of any animal on Earth, live in complex social structures and communicate using sonar-like clicks that travel underwater.
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This study helps to highlight that whales and dolphins have culture and social learning, says Nicola Hodgins, a researcher at Whale & Dolphin Conservation.
“There’s certainly an element of watch and learn in these animals, watching their parents and peers and then mimicking that behaviour, as well as acoustic communication.”
Commercial whaling was banned in the 1980s but tens of thousands of whales are still killed by humans every year. “Today, whales are going to have to learn how to avoid boats and ship strikes,” Hodgins says. “The difference in the number of vessels on the water – everything from military vessels to cruise liners to jet skis – is huge. There’s more nets, too.
“We know that whales and dolphins are incredibly intelligent and must have complex social lives. This fascinating research not only highlights that this happens, but hopefully means we can in turn protect them better.”
Reader Q&A: Do whales sleep?
Asked by: Steven Collins, by email
Whales, dolphins and porpoises need to retain conscious brain activity in order to take a breath because they must be able to tell that their blowhole is at the surface. To get around this, they only sleep with one hemisphere of the brain at a time. This resting state is more like a very light nap and the whale can still swim at the same time.