Eggshell proteins confirm that early humans in Australia ate the eggs of a two-meter-long bird that became extinct more than 47,000 years ago.
Signs of burns on the remains of the ancient shell were discovered several years ago, suggesting that early Australians cooked and ate large eggs from a long-extinct bird, sparking fierce debate over the species that laid it.
Now, an international team led by scientists from the Universities of Cambridge and Turin has put the animal on the evolutionary tree by comparing the protein sequences in the fossil egg powder to those encoded in the genomes of living bird species.
“The time, temperature and chemistry of the fossil determine how much information we can gather,” said co-lead author Professor Matthew Collins, from the University of Cambridge’s Department of Archeology.
“Eggshells are made of mineral crystals that can tightly trap some proteins, preserving these biological data in the harshest environments, possibly for millions of years.”
According to the results published in the journal(a) Proceedings of the National Academy of Sciencesthe ancient whites came from Genyornis: the flightless ‘mihirung’ or ‘thunderbird’, with small wings and huge legs roamed prehistoric Australia, probably in flocks.
Fossil records show that Genornes was over two meters tall, weighed between 220 and 240 kilograms, and laid eggs the size of a melon weighing about 1.5 kilograms. It was among the Australian “megafauna” that disappeared a few thousand years after humans arrived, suggesting that humans played a role in its extinction.
The earliest “strong” date for humans to reach Australia is about 65,000 years ago. The history of burnt eggshell of previously unconfirmed species dates back to about 50-55 thousand years ago, not long before Genyornis was thought to be extinct, at which time humans spread over most of the continent.
Co-lead author Professor Gifford Miller of the University of Colorado said: “There is no evidence of Geniornis extermination in the archaeological record. However, eggshell fragments with unique burning patterns consistent with human activity have been found at various locations on the continent.” .
“This means that early humans did not necessarily hunt these huge birds, but instead routinely broke into their nests and stole their giant eggs for food,” he said. “Human over-harvesting of eggs may have contributed to the extinction of Geniornis.”
While Genyornis has always been a contender as the origin of eggshell, some scholars have argued that due to the shape and thickness of the shell, the most likely candidate was the Progura or “Giant Giant Bird” – another extinct bird much smaller, weighing about 5.7 kilos and resembling a large turkey.
The initial goal was to end the controversy by extracting ancient DNA from parts of the shell, but the genetic material has not survived long enough in the hot Australian climate. Miller turned to researchers from Cambridge and Turin to explore a relatively new technique for extracting a different kind of “biomolecule”: a protein.
Although not rich in genetic data, the scientists were able to compare ancient protein sequences with those of living species using an extensive new database of biological material: the Bird 10 Thousand Genomes (B10K) Project.
“The bird was related to today’s michapods, a group of birds in the lineage of Glyformis, which also contains ground-feeding birds such as chickens and turkeys,” said Professor Beatrice Demarche, first author of the study, from the University of Turin.
The 50,000-year-old eggshell analyzed for the study came from the archaeological site of Wood Point in South Australia, but Professor Miller has previously shown that similar burnt shells can be found at hundreds of sites on Australia’s west coast.
Edition: Estefania Cardeña
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