Millennia before the domestication of chickens and the like: residents of the island of New Guinea may have been breeding poultry as early as 18,000 years ago. They collected cassowary eggs when they were ready to hatch and then reared the birds until they were ready for slaughter. This suggests examination results of eggshells from archaeological sites as well as other indications.
Once upon a time when humans spread across the globe, they encountered communities of animals in the new worlds, which in some cases also included literally outstanding bird species. The sometimes huge flightless ratites included the elephant birds of Madagascar and the moas of New Zealand. It is believed that humans played a role in the extinction of these species. On the other hand, the large ratites of New Guinea have survived to this day: the cassowaries, up to 1.70 meters in size and weighing 60 kilograms, still stride through the forests of the island north of Australia. As part of their study, the researchers led by Kristina Douglass from Pennsylvania State University in University Park have now devoted themselves to researching the history of the human-cassowary relationship in New Guinea.
Archaeological cassowary eggshells in sight
As they report, it is known that the three species of these ratites still serve as a source of food for today’s inhabitants of the island: They are hunted – but it also appears that young animals are raised in the domestic environment and then eaten. As far as the handling of birds in prehistoric times is concerned, however, there is little evidence: bones of cassowaries that can be linked to human activities are rare. However, numerous eggshells of the birds were discovered at archaeological sites, which suggested that they were once used by humans as a source of food.
As part of their study, Douglass and her colleagues have now examined numerous eggshells that come from different cultural layers in two localities in the highlands of New Guinea. They were eggs from the comparatively small highland cassowary Casuarius Bennetti. They have been dated to between 18,000 and 6,000 years ago. In addition to possible traces of processing by humans, the researchers investigated the stage of development of the eggs when they were used. To do this, they used a previously developed method based on the analysis of certain features of the shell. As the researchers explain, the developmental stage of a chick embryo is indicated by the absorption of calcium from the eggshell.
Why so developed eggs?
As they report, the analyzes of the finds led to surprising results: People apparently rarely collected and ate young cassowary eggs. “The majority of the eggshells found at the archaeological sites, however, show the characteristics of a very late stage of development,” reports Douglass. According to the scientists, there are two possible explanations for this. Perhaps people liked to eat so-called baluts, which are still considered a delicacy in Southeast Asia today. These are eggs that are specifically heated and eaten shortly before the hatchling of the well-developed chick. However, the researchers found no evidence of heating on the shells of the eggs when they were ready to hatch. In the comparatively rare shells of the younger eggs from the localities, however, they did come across traces of a preparation.
Therefore, the second possible explanation seems more likely to them: The eggs, which were apparently purposefully collected at a late stage of development, were not eaten, but the people let the chicks hatch. Then the young cassowaries grew up in the area of the camp and could finally be eaten as a large roast, the scientists suspect. According to them, a special behavior of the animals could have played an important role: Similar to other young birds, cassowary chicks can also be imprinted on humans because they mistake the first creature they see after hatching to be the mother.
The scientists cannot directly prove this form of poultry farming up to 18,000 years ago, but it appears at least very plausible: “The results are possibly the earliest known evidence of a form of bird management,” the researchers sum up. “The behavior we suspect apparently existed thousands of years before the chicken was domesticated,” concludes Kristina Douglass.
Source: Pennsylvania State University, Article: PNAS, doi: 10.1073 / pnas.2100117118