Sydney, 11 May 2021: An international team of palaeontologists, led by Dr. Matthew McCurry, Australian Museum Research Institute (AMRI) and the University of New South Wales (UNSW), have discovered surprisingly large brains in prehistoric whales. The new research findings were published today in the prestigious scientific journal Biological Journal of the Linnean Society.

The group of international scientists, including researchers from Japan, United Kingdom and the United States, scanned fossils using hospital CT scanners to estimate the size of their brains.

“The size of the brains in these fossil species revolutionises our understanding of why whales and dolphins evolved large brains,” McCurry said.

Scientists have long debated the reasons why whales and dolphins evolved large brains, that are proportionally as large as those seen in some primates. One of the most popular arguments is that toothed whales (the group that includes sperm whales and dolphins) evolved large brains because of the need to process complex sensory information that they gather through echolocation. The data gathered in this study suggests that non-echolocating whales also possessed large brains.

“This means that large brains arose before echolocation and suggests that it can’t be the only cause of brain size evolution in whales,” McCurry said.

Instead, Dr McCurry suggests that sociality could be a more important driving factor.

Dr Matthew McCurry
Dr Matthew McCurry with a piece of a jaw from one of one of the fossil whales used in the study. Image: James DiLoreto
© Smithsonian Institution

“It’s hard to tell how social a fossilised species was, but we think that the need to live in complex social groups is a more plausible explanation for the evolution of large brains in these species,” McCurry said.

Professor Kristofer Helgen, Chief Scientist and Director of AMRI, said that whales have sophisticated traits and behaviours that are as complex as those of primates, and even humans.

“Whales evolved from terrestrial hoofed animals, which lived around 50 million years ago, to become the largest and one of the most unique animals on our planet,” Helgen said.

“Dr. McCurry’s research on brain size yields valuable information on their history and evolution, adding to the body of whale knowledge with the goal of strengthening conservation efforts,” Helgen said.

The team of researchers used museum collections to CT scan whale fossils and then calculated the size of the cavity where the brain sits to estimate the brain size.

“This study is another great example of how museum collections contribute to our knowledge of important species like whales, a fundamental component of marine ecosystems. As we learn more about whales, we realise that they are more magnificently complex, and even more like us, than we imagined,” Helgen said.

Today, many species of whales are under threat and endangered from whaling, overfishing and pollution. This research illuminates the need for further study and protection of these breath-taking giants of the ocean.

Editor’s note:

Video available here.

AM blog can be found here.

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