Trending Science: Cetaceans having a whale of a time thanks to big brains, says study
Humans evolved their big heads to manage their complex social structures, an idea called the social brain hypothesis. Now a new study conducted by British and American researchers suggests that whale and dolphin brains evolved in much the same way.
Published in the journal ‘Nature Ecology and Evolution’, the study compiled a list of the rich behaviours spotted in 90 different species of cetaceans, including dolphins, whales and porpoises, and found that the bigger the species’ brain, the more complex – indeed, the more ‘human-like’ – their lives are likely to be.
This suggests that the cultural brain hypothesis theory may also apply to whales and dolphins, as well as humans, with species such as the killer whale and sperm whale leading the way. ‘Dolphin and whale societies are at least as complex as what we have observed in primates,’ said evolutionary biologist Susanne Shultz of the University of Manchester. ‘They are extremely playful; they learn from each other, have complex communication. One problem for understanding just how smart they are is how difficult it is to observe them and to understand their marine world. Therefore, we have only a glimpse of what they are capable of.’
The researchers gathered records of dolphins playing with humpback whales, helping fishermen with their catches, and even producing signature whistles for dolphins that are absent – suggesting the animals may even gossip. ‘Killer whales have cultural food preferences, have matriarchs that lead and teach other group members, and cooperatively hunt,’ explained Shultz.
In terms of intra-species food preferences, certain killer whale populations prefer salmon whereas others prefer seals or other whales or sharks depending on their group’s distinct culture. Other large-brained cetaceans also demonstrate sophisticated behaviours. Mother sperm whales organise babysitting duties using other members of their pod to protect their young whilst they hunt for food.
The distinctive vocalisations sperm whales use to communicate sometimes differ depending on where they live, much like regional dialects in human language. Bottlenose dolphins use sea sponges as tools to protect their beaks whilst foraging for food and live in structured communities.
Luke Rendell, a biologist at the University of St Andrews who was not involved in the study, but has done work on sperm whales and their distinctive dialects, warned in ‘The Guardian’ newspaper against anthropomorphising and making animals appear to be like humans. ‘There is a risk of sounding like there is a single train line, with humans at the final station and other animals on their way of getting there. The truth is that every animal responds to their own evolutionary pressures,’ he said.
Whilst humans have managed to spread to all four corners of the Earth thanks to our brains, one should not expect whales or dolphins to take over any time soon. ‘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,’ commented Shultz. ‘Unfortunately, they won’t ever mimic our great metropolises and technologies because they didn’t evolve opposable thumbs.’
last modification: 2017-10-20 17:15:01