Australia’s Global Gift: The origin of songbirds and their sweet tooth (#285)

When you think of iconic Australian contributions to the world, a few things might spring to mind. Vegemite on toast. Marsupial-inspired break dancing. And, of course, the Hemsworths.

But there’s another Aussie export that’s been quietly charming the globe for millennia - songbirds.

Those melodious marvels that flit through forests and gardens across the planet? You can thank Australia for them.

A Sweet Song

For a long time, scientists assumed songbirds had evolved in the Northern Hemisphere and spread southward.

That tidy explanation seemed to fit the pattern of bird classification European explorers began in the 18th and 19th centuries. Upon encountering Australia’s birds, they gave them familiar names, such as wrens, robins, and treecreepers, based on birds they already knew. This practice unintentionally reinforced the belief that Australian birds were simply offshoots of Northern Hemisphere species.

But molecular research beginning in the 1970s started turning that story upside down. Over the past two decades, extensive genetic studies have confirmed that songbirds, or oscine passerines, evolved first in Australia.

In fact, the songbirds of Europe, Asia, Africa, and the Americas all trace their ancestry back to a common ancestor that once sang in the ancient landscapes of Australia. From there, these early vocalists spread out across the globe, evolving into the thousands of diverse species we see and hear today.

A Sweet Twist

But Australia’s avian legacy doesn’t end with birdsong. It turns out our songbirds also carry a sweet surprise.

Most birds, including all their dinosaur ancestors, lost the genes that allow mammals (like us) to taste sweetness. That’s why researchers were stumped by hummingbirds, that feed almost exclusively on sugary nectar. How could they detect sweetness if they lacked the gene for it?

Enter Dr Maude Baldwin, a researcher at the Max Planck Institute for Ornithology. She discovered that hummingbirds had repurposed a gene normally used to detect umami ( the savory taste found in foods like miso soup and mushrooms) to sense sweetness. A clever evolutionary twist.

But could the same thing be true of songbirds?

Dr Baldwin suspected so. In fact, she was so intrigued that she traveled to Australia and collected samples from native songbirds and parrots to find out.

An Australian Origin of Song and Taste

The results, published in groundbreaking research, revealed that Australian songbirds were indeed the first to repurpose the umami gene to detect sugar, a trait that then spread through the evolutionary tree of songbirds across the globe.

In other words, not only did Australia give the world its songbirds -  it gave the world their sweet tooth as well.

Fascinatingly, while both hummingbirds and songbirds use the same umami gene to detect sweetness, they’ve evolved different molecular mechanisms to do so. This means these two bird groups, separated by millions of years and continents, arrived at the same solution via different evolutionary paths.

This phenomenon is known as convergent evolution.

And there's more to come. Many Australian parrots also feed on sweet substances like nectar, lerp, and honeydew. Dr Baldwin’s team is now investigating how these close cousins of songbirds sense sweetness.

Rick’s Commentary

Australia isn’t just home to quokkas, boomerangs, and barbecued prawns.

It’s also the cradle of birdsong and the birthplace of a biological innovation that lets birds enjoy the sugary rewards of flowers, fruits, and tree sap.

Further Reading

Evolution of sweet taste perception in hummingbirds by transformation of the ancestral umami receptor. https://pmc.ncbi.nlm.nih.gov/articles/PMC4302410/

Early origin of sweet perception in the songbird radiation. https://www.science.org/doi/10.1126/science.abf6505

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