Which came first, the chicken or the egg? Scientists provide the answer from the perspective of evolution

On World Egg Day, MailOnline posed this question to evolution experts.

Although eggs evolved millions of years before chickens, scientists stress that this does not necessarily mean that the egg came before the chicken.

What is an egg?

Eggs have been around for a long time, “almost as long as life itself.”

With the exception of mammals, most animals lay eggs. According to Jules Howard, author of the book “Infinite Life,” which discusses the evolution of eggs, eggs were evolution’s way of passing genes to future generations.

Before the appearance of eggs, organisms reproduced by cloning, which made them vulnerable to death due to diseases. As for eggs, they contribute to the emergence of genetic diversity and the ability to resist diseases and parasites.

The first eggs were completely different from the shape we know today, and were probably laid by primitive creatures such as jellyfish or marine worms hundreds of millions of years ago. About 600 million years ago, eggs were very small, barely larger than a human hair, and were pumped across the oceans, before settling on the bottom of the sea.

Since that distant time, living organisms have relied on this primitive form of reproduction, which means that the egg came millions of years before the appearance of the chicken.

What is chicken?

The origin of domestic chickens goes back to a species of red chicken, called Gallus gallus, that evolved about 50 million years ago.

Initially, it was believed that humans domesticated chickens about 10,000 years ago, but new research indicates that domestication may have occurred between 1650 and 1250 BC, that is, about 3,500 years ago, in regions of Southeast Asia, where birds adapted to the presence of humans and gradually evolved into What we know today as chickens, or Gallus gallus domesticus.

Which came first: the dinosaur or the egg?

While chickens are only a few thousand years old, eggs date back millions of years, with the first known eggs dating back to the Carboniferous period, about 358 to 298 million years ago. These eggs were from primitive reptiles, and were probably soft-shelled.

In the Early Jurassic period, hard-shelled eggs developed, and dinosaurs were the first to lay such eggs. Fossilized eggs dating back to 195 million years ago were found, laid by long-necked dinosaurs, such as Brontosaurus and Diplodocus, which are very similar to the eggs of many modern birds and reptiles.

In 2023, scientists discovered a huge hatchery containing 91 nests of titanosaurs, a type of dinosaur, containing 256 eggs, indicating that these giant dinosaurs were nesting together like birds.

The argument in favor of the chicken

Although eggs are clearly older than chickens from an evolutionary perspective, the answer depends on how the question is interpreted.

If the question is about “chicken egg,” then the first chicken must have hatched from an egg laid by its wild ancestor. So, according to this interpretation, it can be said that the chicken came first.

The conclusion, according to scientists, says: From an evolutionary perspective, the egg certainly came before the chicken, but if the question concerns the chicken egg specifically, then the first chicken must have hatched before the first true “chicken egg” was laid.

Source: Daily Mail