Prehistoric penguin skull reveals losing ability to fly did NOT cause brains to shrink

September 2024 · 6 minute read

Not being able to fly has given penguins their unrivalled swimming abilities.

But when the penguins stopped taking to the skies millions of years ago, the structure of the birds' brains did not change right away, according to a new study.

This means the loss of flight itself did not modify the brain structure, as scientists had previously thought it might, nor did they lose the ability to fly by a change in the brain. 

When penguins stopped taking to the skies millions of years ago and started taking to the seas instead, the structure of the birds' brains did not change right away, according to a new study. This means the loss of flight itself did not modify the brain structure, as scientists had previously thought it might

When penguins stopped taking to the skies millions of years ago and started taking to the seas instead, the structure of the birds' brains did not change right away, according to a new study. This means the loss of flight itself did not modify the brain structure, as scientists had previously thought it might

'What this seems to indicate is that becoming larger, losing flight and becoming a wing-propelled diver does not necessarily change the [brain] anatomy quickly,' said James Proffitt, a graduate student at the University of Texas at Austin's school of Geosciences, and leader of the research.

'The way the modern penguin brain looks doesn't show up until millions and millions of years later.'

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Proffitt conducted the research with Julia Clarke, a department, and Paul Scofield, the senior curator of Natural History at the Canterbury Museum in Christchurch, New Zealand, where the skull fossil is from.

BIRD BRAIN: THE SKULL STUDY

Not being able to fly has given penguins their unrivalled swimming abilities.

But when penguins stopped taking to the skies millions of years ago, the structure of the birds' brains did not change right away. 

This means the loss of flight itself did not modify the structure, as scientists had previously thought it might.

Proffitt and his team looked at the skull of a penguin that lived in New Zealand over 60 million years ago.

According to Proffitt, their results show the penguin would have lived much like penguins we see today.

They looked at the skull of a penguin that lived in New Zealand more than 60 million years ago.

According to Proffitt, the results show the penguin would have lived much like penguins we know today.

Today's penguins have been diving instead of flying for tens of millions of years, but the change was quite new for this ancient penguin.

That's why this particular skull is special, because it was the oldest known skull to have followed just after penguin's lost their flight. 

This gave the researchers a glimpse into what penguins' brains looked like just after they went through the huge evolutionary change from flying to swimming. 

The skull shape is determined by the structure of the brain, so by looking at the skull, researchers can tell much about what the brains of these animals were like.

They used X-ray imaging techniques to study the skull then modelled the brain using computer software, making a kind of 'digital mould'.

An ancient penguin skull and 'digital mould' or endocast. Scale bar is 2.5cm and letters indicate parts of the brain. This particular skull is special because it was the oldest known skull to have followed just after penguin's lost their flight

An ancient penguin skull and 'digital mould' or endocast. Scale bar is 2.5cm and letters indicate parts of the brain. This particular skull is special because it was the oldest known skull to have followed just after penguin's lost their flight

PENGUINS: MASTERS OF THE SEA

There are 18 species of penguin - 13 of which are declining and five that are considered endangered

There are 18 species of penguin - 13 of which are declining and five that are considered endangered

There are 18 species of penguin - 13 of which are declining and five of them are considered endangered.

While most people associate penguins with Antarctica, penguin populations can also be found in South America, South Africa, Australia and New Zealand, as well as many small islands in the southern Pacific Ocean. 

While swimming, penguins will leap in shallow arcs above the surface of the water, a practice called porpoising.

This coats their plumage with tiny bubbles that reduce friction, allowing them to swim as fast as 20 miles per hour

The light front and dark colour of classic penguin plumage is called counter-shading and provides camouflage from above and below to protect penguins in the water. 

Penguins’ eyes work better underwater than they do in the air, giving them superior eyesight to spot prey while hunting, even in cloudy, dark or murky water. 

Depending on the species, a wild penguin can live 15-20 years. During that time, they spend up to 75 per cent of their lives at sea.

The researchers thought that loss of flight would impact brain structure, making the brains of ancient penguins and modern penguins similar in certain regions. 

However, after analysing the brain mould and comparing it to modern penguin brain anatomy, no such similarity was found, Proffitt said. 

'The brain anatomy had more in common with skulls of modern relatives that both fly and dive such as petrels and loons, than modern penguins,' he said.

It's difficult to know exactly why modern penguins' brains look different to their ancestors'.

It's difficult to know exactly why modern penguins' brains look different to their ancestors, the researchers said, but it is possible that millions of years of flightless living created gradual changes in the brain structure

It's difficult to know exactly why modern penguins' brains look different to their ancestors, the researchers said, but it is possible that millions of years of flightless living created gradual changes in the brain structure

'It's possible that millions of years of flightless living created gradual changes in the brain structure.

'But the analysis shows that these changes are not directly related to initial loss of flight because they are not shared by the ancient penguin brain.'

Similarities in the brain shapes of the ancient species and diving birds living today suggest diving behaviour may be associated with some structures in the brain.

'The question now is do the old fossil penguins' brains look that way because that's the way their ancestors looked, or does it have something maybe to do with diving?' Proffitt said.

'I think that's an open question right now.'

TOASTY HUG OF PENGUIN HUDDLES

They endure some of the coldest temperatures on the planet as they nest through the Antarctic winter, but emperor penguins get so warm as they huddle together on the ice that they have to resort to eating snow to cool down.

Researchers have found some of the birds get so hot in the tight bundle of bodies they risk overheating.

They also discovered huddles are more complicated and temporary than previously thought - lasting on average 50 minutes at a time. 

Previous estimates suggested the penguins hunkered down for as long as the storms lasted, which could be hours.

The birds were thought to stay warm by rotating from the outside to the inside of the huddle. 

But scientists at the University of Strasbourg in France have found the huddles regulate the birds' temperatures in a more complicated way, with some members breaking free to cool down. 

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