Proteins extracted from prehistoric eggshell fragments found in Australian sands confirm that the continent’s first humans consumed the eggs of a two-meter-tall bird that went extinct more than 47,000 years ago.
Scorch marks discovered on remnants of ancient shells years ago suggest early Australians cooked and ate large eggs from a long-extinct bird, leading to fierce debate over which species were responsible for them. have laid.
Now an international team led by scientists from the Universities of Cambridge and Turin have placed the animal on the evolutionary tree by comparing the protein sequences of powdered egg fossils to those encoded in the genomes of species. live avians.
“The weather, temperature and chemistry of a fossil all dictate how much information we can glean,” said co-lead author Professor Matthew Collins from the University of Cambridge’s Department of Archaeology.
“Eggshells are made up of mineral crystals that can tightly trap certain proteins, preserving that biological data in the harshest environments – potentially for millions of years.”
According to results published in the journal Proceedings of the National Academy of Sciencesthe old eggs came from Genyornis: a huge flightless “mihirung” – or “Thunder Bird” – with tiny wings and massive legs that roamed prehistoric Australia, possibly in flocks.
The fossil record shows that Genyornis was over two meters tall, weighed between 220 and 240 kilograms, and laid melon-sized eggs of about 1.5 kg. It was among the Australian “mega-fauna” to become extinct a few thousand years after humans arrived, suggesting people played a part in its extinction.
The first “robust” date for the arrival of humans in Australia dates back to around 65,000 years ago. Burnt eggshells of previously unconfirmed species all date to around 50-55,000 years ago – shortly before Genyornis it is thought to have died out – by this time humans had spread over most of the continent.
“There is no evidence of Genyornis butchery in the archaeological archives. However, eggshell fragments with unique burn patterns consistent with human activity have been found in different locations across the continent,” said co-lead author Professor Gifford Miller of the University of Colorado.
“This implies that early humans didn’t necessarily hunt these huge birds, but regularly raided nests and stole their giant eggs for food,” he said. “Human overexploitation of eggs may well have contributed to Genyornis extinction.”
While Genyornis was always a contender for the mysterious egg layer, some scientists have argued that due to the shape and thickness of the shell, a more likely candidate was the Program or “giant malleefowl”: another extinct bird, much smaller, weighing around 5-7 kg and resembling a large turkey.
The initial ambition was to put an end to the debate by extracting ancient DNA from pieces of seashells, but the genetic material had not sufficiently survived the hot Australian climate.
Miller turned to researchers in Cambridge and Turin to explore a relatively new technique for extracting another type of “biomolecule”: protein.
Although less rich in hereditary data, scientists were able to compare the sequences of ancient proteins to those of living species using a large new database of biological material: the Bird 10,000 Genomes (B10K) project.
“The Program was related to today’s megapodes, a group of birds of the galliform lineage, which also contains terrestrial eaters such as chickens and turkeys,” said the study’s first author, Professor Beatrice Demarchi of the University of Torino.
“We found that the bird responsible for the mystery eggs appeared before the galliform lineage, which allows us to rule out the Program hypothesis. This supports the implication that the eggs eaten by early Australians were laid by Genyornis.”
The 50,000-year-old eggshell tested for the study came from the Wood Point archaeological site in South Australia, but Professor Miller has already shown that similar burnt shells can be found at hundreds of sites on the coast west of Ningaloo.
The researchers point out that the Genyornis The egg-harvesting behavior of early Australians likely mirrors that of early humans with ostrich eggs, the shells of which have been unearthed at archaeological sites across Africa dating back at least 100,000 years.
Professor Collins added: “While ostriches and humans have co-existed throughout prehistory, levels of exploitation of Genyornis the eggs of the first Australians may have ultimately proved more than the breeding strategies of these extraordinary birds could bear.