Which came first: the chicken or the egg?

Which came first: the chicken or the egg? It’s been one of those great dilemmas ever since the philosopher Plutarch put it in writing nearly 2,000 years ago. 

While the chicken and egg is now used as a metaphor for similar cause-and-effect dilemmas, thankfully science has a (pretty) definitive answer to the original question.   

chicken or the egg
(Getty Images)

The egg came before the chicken, technically. Whether you look at the question as all eggs on earth, or a specific chicken hatching from an egg, the egg got there first. Effectively every multicellular organism on earth – including all animals and plants – produces eggs. For however long there has been any remotely advanced form of life on the planet, there have been eggs. It’s unknown when exactly this began, but it could have been as long as 2 billion years ago, well into the Precambrian – the earliest part of the Earth’s history. 

Eggs as we conventionally think of them, spherical and with a tough outer membrane, appeared hundreds of millions of years before chickens. Birds evolved from reptiles and reptiles evolved from amphibians, and the gradual evolution means the first eggs were laid by species very different from chickens. 

chicken or the egg
We don’t know who came first on this occasion. Fun Runners dressed as a chicken and an egg warm up before the 2004 London Marathon. (Photo by Christopher Lee/Getty Images)

In fact, the chicken might have only appeared as recently as 10,000 years ago and as a result of humans breeding them. They are domestic birds and have spread throughout the world via trade and commerce since their origin, believed to be in northern China where the earliest bones were found.

The ancestor of the chicken is the tropical red jungle fowl, which looks very similar and is still found across large parts of Asia today. When exactly it became the new species – the chicken – is impossible to pinpoint. But considering the first chicken would have appeared from a jungle fowl egg, and therefore laid the first purely chicken egg upon its own maturity, you could argue that the chicken got there first.

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