Ancient eggshells have led a team of scientists to a startling discovery: as early as 18,000 years ago, humans may have been hatching and raising young cassowaries, considered one of the world’s most dangerous birds.
The researchers have shared their findings in a study published this week in the journal Proceedings of the National Academy of Science, after studying eggshells found at two sites on New Guinea.
The discovery may be the earliest example of humans managing avian breeding, thousands of years before the chicken was domesticated.
“It’s a really intriguing example of how people have just an incredible knowledge of their environment and the animals in it,” said Kristina Douglass, the lead author of the study and an archeologist at Penn State University in Pennsylvania.
Here is part of her conversation with As It Happens host Carol Off.
Professor Douglas, can you just describe what a cassowary looks like?
Cassowaries are incredible birds. They’re part of this group of birds called ratites, which are large, flightless birds. Many people think of ostriches, but kiwi are also a part of that group, and cassowaries are sort of medium-sized ratites.
In the case of the cassowaries we’re studying on New Guinea, they stand about a metre or so off the ground, a little bit taller than that, perhaps, [and] weigh about 20 kilos and have this beautiful dark plumage.
They have black feathers and then this very brightly coloured head that has a crest, or a casque, on top that’s made out of, sort of a hard material, kind of like your fingernails.
They’re pretty impressive looking birds.
They’re often compared to dinosaurs, right?
I think sometimes they’re compared to dinosaurs … because of the way they can attack if they feel threatened. They have these four-inch-long claws on their feet that they can use to eviscerate their target if they feel threatened, though usually they’re pretty shy and prefer to avoid any confrontation.
But people should give them a wide berth, right? There have been some pretty major incidents of encounters with cassowaries.
Unfortunately, most of those encounters are linked to people disturbing the animals and trying to get a rise out of them, which is unfortunate. They are, you know, wild animals that should be respected in their natural habitat.
Yet your research indicates that people may have not been giving them a wide berth about 18,000 years ago. What did the eggshells that you discovered tell you about the possible relationship between these birds and people?
I’m looking at eggshells from these archeological sites in [the montane rainforests of] New Guinea.
What we found is that people were selecting eggs at a very late stage in the embryo’s development. So they were selecting eggs that would have contained a fully-formed cassowary chick, which is really intriguing and leads to two possibilities.
One possibility is that people had a preference for eating developed chick embryos, as opposed to making an omelette out of yolk and albumin.
Or they were trying to hatch the eggs and potentially rear cassowary chicks. And we think that they may have been doing both.
Why isn’t it possible … these were just eggs they were raiding from the wild nests? I mean, despite the danger of doing that.
The pattern that we’re seeing is not random.
You would expect that if people were sort of haphazardly collecting eggs … that there would be more of a random pattern in terms of the age of the chick inside the egg.
In other words, you would find a lot of eggs that were in the early stages of chick development, some in the middle stage, some in the late stage. But what we’re finding is that the eggs at these archeological sites tend to be in the late stage more than would be expected if it was random.
To what end might these people in New Guinea have been rearing these chicks?
They’re the largest vertebrate in the highlands, and as a large animal, they represent an important source of meat for subsistence.
But they’re also, in New Guinea today, valued for their feathers, for their bones. People make all kinds of ceremonial wear and objects out of cassowary feathers and cassowary bones, and they’re highly valued trade items. People trade the birds for big ceremonies and feast or save them up as bride price.
They’re incredibly valuable. And people may have been raising the chicks because that provides a more efficient access to the resource.
If you think about the difficulty of hunting an adult cassowary in the wild, as compared to having a chick imprint on you … being able to raise that chick to adulthood makes the resource really readily accessible.
Back to how dangerous these birds are…. Isn’t it kind of … an issue when you do have a full grown cassowary who’s turning on you?
What we see in New Guinea today is that people frequently raised cassowaries and they keep them in pens, you know, around their houses — or they even have them as chicks walking around after them in their house.
As chicks, when they imprint — meaning that when they see a human as the first sort of thing after the chick has hatched — they form a really intimate bond and will follow the person around and will not display that kind of aggression that you might expect of a wild bird, until perhaps they reach adulthood, when we have documented, you know, experiences of people seeing that cassowary behaviour, that slightly ornery, flightless bird behaviour tends to come out.
So what changes if, 18,000 years ago there were people who were domesticating these birds?
This really should expand our thinking about domestication as a spectrum.
In our case, we don’t have evidence for full-blown domestication. What we have evidence for is selective harvesting and management of a resource that would be on one end of the spectrum of human-animal interactions or human-animal … management.
It should get us to think about other examples that may be out there of how people developed these kinds of relationships with animals that are more intimate than we might have guessed at really early times in our history.
Written by Andrea Bellemare. Produced by Katie Geleff. Q&A edited for length and clarity.