Which came first, the chicken or the egg?
Believe it or not, this question has its roots in ancient Greece, where philosophers used it as an excuse to argue about cause and effect. What’s more, it’s what is known as a paradox — a situation or statement that appears to present contradicting facts, both of which can logically be true.
Some might say the chicken came first, since you can’t have an egg without a chicken to lay it. But others might argue the egg came first, since all chickens begin life inside of an egg.
A paradox, right? Not if you want to get technical. The question has a rather simple answer if you talk to an ancient egg expert.
“It’s pretty straightforward,” said Jasmina Wiemann, a molecular paleobiologist at Yale University. (Paleobiology is the science of fossil organisms.) “The egg is much older, evolutionarily, than the chicken.”
Chickens, as we know them, probably became domesticated about 10,000 years ago. But the animals that they descend from, known as jungle fowl or Gallus, can be dated back 21 million years.
Now that might sound pretty ancient, but the incredible, edible egg has been around for hundreds of millions of years.
For instance, scientists recently discovered a fossilized bird from northwestern China with an egg stuck inside its body. At 110 million years old, this species, known as Avimaia schweitzerae, would have flitted about in a world dominated by dinosaurs. It’s the most ancient bird egg ever discovered.
Eggs were around long before this, even. Dinosaurs, birds, reptiles and even mammals are known as amniotes, a branch of the vertebrate family tree that evolved approximately 300 million years ago, Wiemann said.
This pushes the origins of the egg back even further. However, these eggs would have looked quite a bit different from what’s in your refrigerator.
The earliest eggs would have been soft, sort of like turtle eggs you might see on the beach, Wiemann said. The crunchy, brittle, protective coating came later.
By the way, if you thought it odd to see the mammals lumped into a group with egg-laying stegosauruses, crocs, ostriches and tortoises, you should know that egg-laying is part of our evolutionary history. In other words, if you go back far enough in time, humans have ancestors that would have laid eggs. And mature female humans today still produce eggs through a process called ovulation. The eggs stay inside of humans — and they’re squishy and lack a shell.
Even weirder, some mammals still reproduce by laying eggs that can survive outside the body. They’re known as monotremes, which include species such as the duck-billed platypus and echidna (pronounced ih-KID-nuh).
Now, here’s a question for you — which came first, the egg or the echidna?