New research suggests humans stole the eggs of cassowaries 18,000 years ago and then raise the chicks with their own hands.

That can be read in the magazine Proceedings of the National Academy of Sciences. The scientists rely on an analysis of more than 1,000 eggshells recovered from archaeological sites in New Guinea that housed a lesser cassowary between 18,000 and 6,000 years ago.

eggshells

“I’ve been researching eggshells from archaeological sites for years,” said researcher Kristina Douglass. “And I came across a study that dealt with the eggshells of turkeys.” And in that study, researchers showed that the eggshell changes throughout the development of the embryo. This is because the developing chick extracts calcium from the eggshell. This way small pits gradually appear in the inside of the eggshell. It means that through a meticulous analysis of scraps of eggshell left behind, you can determine how advanced or how old the chick was when it hatched or was taken out of the egg.

Cassowaries

Douglass and colleagues decided to apply this approach to more than 1,000 fragments of 18,000- to 6,000-year-old eggshells recovered from two different archaeological sites in New Guinea that once housed cassowaries. “What we found was that most of the eggshells were collected during the late stages of development,” Douglass said. “They (the people who lived here, ed.) either loved balut eggs or raised the chicks.” Balut eggs are still a (not undisputed) delicacy in some parts of Asia today. They are fertilized eggs (often from a duck) that are boiled or steamed in their entirety, after which the embryo – which is often quite well developed – can be consumed in its entirety. Douglass, however, does not consider it plausible that prehistoric humans were after this delicacy. She points out that many eggshells have been recovered that have not seen fire up close. “We therefore argue that the people let the eggs hatch and did not eat them.”

Cassowaries are sturdily built flightless birds. There are three species, of which the helmeted cassowary is the largest. This bird can grow up to 1.60 meters long and weigh 60 kilos. There are also the orange-necked cassowary and the dwarf cassowary. The latter is the smallest species and grows to about 1 meter in length. Cassowaries are also known as ‘the most dangerous birds on earth’. This can be traced back to the sharp and long claw on one of their toes. With this claw, the cassowary – when cornered – can also inflict serious or even fatal injuries on people.

Great flightless bird

The idea that humans kept cassowaries as early as 18,000 years ago is quite remarkable. “This happened thousands of years before the chicken was domesticated. And this is no small poultry either. It is a huge flightless bird that can do quite a bit. It is most likely the dwarf variety that can weigh about 20 kilos.”

imprint

At the same time, the choice to keep cassowaries is also not completely illogical. “They are easy to keep and raise,” Douglass says. Also, they are very receptive to imprinting; when they first see a human as soon as they hatch, they will think it is their mother and follow this person everywhere.

Collect the eggs

Obtaining the cracking eggs would have taken some effort. Prehistoric people needed to know where the cassowaries’ nests were and when the eggs were laid. They also had to remove the eggs from the nest shortly before they were due to hatch without incurring the wrath of the father who incubates the eggs. “Field biologists report that nests are difficult to find, are not located in the same place every year and are often in dense vegetation (…) Once breeding begins, the males do not leave the nest,” the researchers write. It is unclear how people managed to get hold of the eggs. It is also unknown why people took the eggs away and raised chicks. The cassowary’s flesh, feathers, bones and eggs are valuable today, and may have been so in prehistoric times, the researchers said.

Research among modern populations of cassowaries has shown that they are very sensitive to predation and habitat disturbance. Based on that, you would think that the removal of eggs and with it a new generation would also have had a significant impact on prehistoric populations. But that doesn’t seem to be the case, the researchers say. They point out that eggshells have been found abundantly at archaeological sites over a long period of time. “It suggests that cassowaries were relatively resistant to human exploitation.”