When humans look up at the night sky, we often wonder if the universe holds any other complex societies created by intelligent life. It does, many scientists say, and they've been under our noses all along.
Humans have outcompeted other animals largely due to our gigantic brains, which evolved along with our byzantine social life and deep cultural knowledge. Yet while we are still unrivaled as Earth's biggest nerds, a new study suggests our species has "a unique and striking parallel" to another group of Earthlings: whales and dolphins.
These marine mammals are already famously clever, but the new study explores the social and cultural roots of their intelligence. Using information from 90 different species of whales, dolphins and porpoises (known as cetaceans), its authors built an unprecedented database of social behaviors and brain sizes. They report "overwhelming evidence" of sophisticated social skills and cooperative traits "similar to many found in human culture," according to a news release from the University of Manchester.
Those abilities include forming complex alliances, cooperative hunting, teaching each other how to hunt and use tools, complex vocalizations with regional dialects, vocal mimicry, name recognition, working with different species and social play.
The researchers used their database to test the social brain hypothesis (SBH) and the cultural brain hypothesis (CBH), two related evolutionary theories that were originally developed to explain the big brains of primates. They found that brain expansion — or encephalization — can be predicted in cetaceans based on their social structure and group size, and that brain size predicts the breadth of the animals' social and cultural behaviors. Scientists think human brains grew huge partly in response to our complex social structures, and this suggests whales and dolphins underwent a similar process at sea.
"As humans, our ability to socially interact and cultivate relationships has allowed us to colonize almost every ecosystem and environment on the planet," says study co-author Susanne Shultz, an evolutionary biologist at the University of Manchester, in a statement. "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 behavioral richness of marine mammals provides a unique and striking parallel to the large brains and hyper-sociality of humans and other primates on land," Shultz adds. "Unfortunately, they won't ever mimic our great metropolises and technologies because they didn't evolve opposable thumbs."
Yet despite our many anatomical differences, including brain structure, whales and dolphins have evolved eerily human-like abilities, notes co-author Kieran Fox, a neuroscientist at Stanford University. There is a risk of anthropomorphizing, or projecting human traits onto other animals, but there is also a risk of underestimating intelligence in other species.
"Cetaceans have many complex social behaviors that are similar to humans and other primates," Fox says in a statement. "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."
This research isn't just about heralding the intelligence of whales and dolphins, adds co-author Michael Muthukrishna, a professor of economic psychology at the London School of Economics: "In order to move toward a more general theory of human behavior, 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."
In fact, as Muthukrishna tells the Guardian, whales and dolphins are the kinds of nonhuman intelligent life forms we often wonder about while gazing at the stars. "We don't have to look at other planets to look for aliens," he says, "because we know that underwater there are these amazing species with so many parallels to us in their complex behaviors."
Related on MNN: Listen to these haunting songs sung by whales