Are Dolphins Held Back From Evolving Because They Don’t Have Opposable Thumbs?

(Telegraph) Dolphins have ‘human-like’ societies…but are held back by a lack of opposable thumbs, say scientists

Whales and dolphins live in human-like societies and share similar brain evolution to primates and man, scientist have concluded.

A new study which looked at 90 species found a link between brain size and social and cultural traits in marine mammals.

It is the first time that scientists have considered whether ‘social brain hypothesis’ applies to whales and dolphins, as well as humans. The theory suggests that intelligence developed as a means of coping with large and complex social groups.

Just like humans, whales and dolphins live in tightly-knit social groups, cooperate with other species, talk to each other and even have regional dialects.

They also engage in cooperative hunting, and pass on their skills to younger members. Some even have signature whistles, which are believed to represent names, so they can call to individuals.

The study showed it was possible to predict the brain size of intelligent marine mammals based on the complexity of their social and cultural structures.

The researchers conclude that, just like humans, whale and dolphin cognition may have arisen to cope with the challenges of social living.

Dr Susanne Shultz, an evolutionary biologist in the University of Manchester’s School of Earth and Environmental   Sciences, said: “As humans, our ability to socially interact and cultivate relationships has allowed us to colonise almost every ecosystem and environment on the planet.

“We know whales and dolphins also have exceptionally large and anatomically sophisticated brains and, therefore, have created a similar marine based culture.

“That means the apparent co-evolution of brains, social structure, and behavioural richness of marine mammals provides a unique and striking parallel to the large brains and hyper-sociality of humans and other primates on land.

“Unfortunately they won’t even mimic our great metropolisis and technologies because they didn’t evolve opposable thumbs.”

The study demonstrates that these societal and cultural characteristics are linked with brain size and brain expansion – also known as encephalisation.

Encephalisation, underpins humans’ sophisticated social cognition, including language, joint attention, shared goals, teaching, consensus decision-making, and empathy.

Dr Kieran Fox, a neuroscientist at Stanford University, added: “Cetaceans have many complex social behaviours that are similar to humans and other primates.

“They, however, have different brain structures from us, leading some researchers to argue that whales and dolphins could not achieve higher cognitive and social skills.

“I think our research shows that this is clearly not the case. Instead, a new question emerges: How can very diverse patterns of brain structure in very different species nonetheless give rise to highly similar cognitive and social behaviours?”

Researchers say the findings could help scientists also understand more about how humans have been so successful.

Dr Michael Muthukrishna, Assistant Professor of Economic Psychology at LSE, added: “This research isn’t just about looking at the intelligence of whales and dolphins, it also has important anthropological ramifications as well.

“In order to move toward a more general theory of human behaviour, we need to understand what makes humans so different from other animals.

“And to do this, we need a control group. Compared to primates, cetaceans are a more “alien” control group.”

The research was published in the journal Nature Ecology & Evolution.

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