150-year-old platypus and echidna specimens discovered which prove some mammals lay eggs

Jars of tiny platypus and echidna specimens, collected in the late 1800s by the scientist William Caldwell, have been discovered in the stores of Cambridge’s University Museum of Zoology.

At the time of their collection, these specimens were key to proving that some mammals lay eggs – a fact that changed the course of scientific thinking and supported the theory of evolution.

The collection had not been catalogued by the museum meaning that until recently staff had been unaware of its existence. The find was made when Jack Ashby, assistant director at the museum, was doing research for a new book on Australian mammals.

He said: “It’s one thing to read the 19th century announcements that platypuses and echidnas actually lay eggs. But to have the physical specimens here, tying us back to that discovery almost 150 years ago, is pretty amazing.

“I knew from experience that there isn’t a natural history collection on Earth that actually has a comprehensive catalogue of everything in it, and I suspected that Caldwell’s specimens really ought to be here.”

That proved to be the case as three months after Ashby asked collections manager Mathew Lowe to keep an eye out, a small box of specimens was found in the museum with a note suggesting they were Caldwell’s. Ashby’s investigations confirmed this.

Until Europeans first encountered platypuses and echidnas in the 1790s, it had been assumed that all mammals give birth to live young. Jack said: “In the 19th century, many conservative scientists didn’t want to believe that an egg-laying mammal could exist, because this would support the theory of evolution – the idea that one animal group was capable of changing into another.”

He added: “Lizards and frogs lay eggs, so the idea of a mammal laying eggs was dismissed by many people – I think they felt it was degrading to be related to animals that they considered ‘lower life forms.’”

The newly discovered collection includes echidnas, platypuses and marsupials at varying life stages from fertilised egg to adolescence. Caldwell was the first to make complete collections of every life stage of these species – although not all of the specimens have been found in the museum.

Ashby notes that over the last two centuries, scientists have consistently belittled Australian mammals by describing them as strange and inferior. He believes that this language continues to affect how we describe them today, and undermines efforts to conserve them.

He said: “Platypuses and echidnas are not weird, primitive animals - as many historic accounts depict them - they are as evolved as anything else. It’s just that they’ve never stopped laying eggs. I think they’re absolutely amazing and definitely worth valuing.”

Visit museum.zoo.cam.ac.uk.

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