Bottlenose dolphins adapt to new situations by learning from a wide array of influencers

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Think of the last time you learned something from a friend. Was it a game? A cool trick? A lifesaving skill? Turns out, bottlenose dolphins learn from their peers too. This may not seem all that surprising, but up until recently, the only type of learning scientists had observed in dolphins was parent-child learning—the “do as mother does” strategy. Now, it seems some young dolphins have found a new way of capturing food, and it’s spreading like any online trend—from friend to friend, without (too many) moms involved.

The hip new foraging technique is called “shelling.” A dolphin chases a fish into a large shell (such as that of a sea snail), carries the shell up to the surface of the water using its snout, or rostrum, then dumps the water out of the shell in such a way that the fish falls right into the dolphin’s open mouth. This is only the second reported case of tool usage in dolphins. The other technique, called “sponging,” is where a dolphin carries a sea sponge on the tip of its rostrum and uses it to sift through rocks and broken coral on the seafloor. The poking and prodding stirs up fish that normally hide amongst the sediments and debris, and the sponge, worn like a protective glove, prevents the dolphins’ rostra from being scraped up in the process. Interestingly, knowledge of the sponging technique tends to be passed on consistently from mother to child. Statistical analysis of shelling, on the other hand, indicated that an estimated 57% of dolphins learned the technique through “social transmission,” from peers or older non-parent individuals. 

Biologists have theorized that when environmental conditions are stable, animals will rely on the wisdom of their parents or other elders in their group. This is a safe bet, since older generations have more experience, and have had time to test out various behaviors. When there is rapid environmental change, however, it may carry more of an advantage to become more experimental, since the elders’ techniques may be outdated given the new circumstances. 

The shelling behavior and social learning of bottlenose dolphins provides support for this theory. In 2011 there was a severe marine heatwave that caused catastrophic ecological damage in Shark Bay, the home of these bottlenose dolphins, and scientists saw a marked increase in shelling behavior in the years after. 

As our planet experiences more and more rapid environmental change, humans may need to take one from the dolphins, encouraging innovation and knowledge sharing both between and within generations. Wisdom passed from parent to child is crucial for an individual’s survival, but when new ideas can also be introduced and spread from peer to peer, a population’s resilience will increase exponentially.

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For an individual with average group size (each individual’s average number of group members averaged across the population), s was estimated to be 15.6 (95% confidence interval [CI] 2.06–145), indicating a 15.6-fold increase in the social learning rate per unit connection with informed individuals relative to the baseline level of asocial learning. This corresponds to an estimated 57% (95% CI 41%–74%) of dolphins learning shelling by social transmission. The estimated strength of social transmission stayed the same even if the environmental and/or genetic networks were added to the best model.

Journal article
Integrating Genetic, Environmental, and Social Networks to Reveal Transmission Pathways of a Dolphin Foraging InnovationCurrent BiologyWild, S., Hoppitt, W. J. E., Allen, S. J., & Krützen, M.

This highly specific tool use has implications for cognition and brain evolution among cetaceans and could even be considered a case of problem solving, a phenomenon difficult to document in the wild, but well established in studies of captive bottlenose dolphins [48]. Our study demonstrates how bottlenose dolphins might use these skills in their natural environment and provides insight into the ecological and evolutionary pressures that promote higher-level cognition. Spongers may have solved the problem of detecting and extracting swimbladderless prey from below a sharp and rough substrate by probing the seafloor with a soft sponge tool.

Journal article
The Ecological Conditions That Favor Tool Use and Innovation in Wild Bottlenose Dolphins PLOS ONEPatterson EM, Mann J

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