Which Came First? The Egg or the Chicken

An age-old riddle, a viral reel, and what the science actually says.

Nothing in biology makes sense except in the light of evolution.

Theodosius Dobzhansky

The question that refuses to die

Some questions are older than our grandfathers’ grandfathers. This one sits comfortably in the hall of fame of conversations that never truly end, right next to “Who sent you?” and “Have you eaten?”

Which came first, the egg or the chicken?

It landed on my phone again this week in an Instagram reel. Short, punchy, supremely confident. The kind of reel that ends with the narrator folding his arms like a man who just settled a land dispute in Abeokuta. And it got me thinking. Not because the question is new, but because it hit me that most of us have been answering it with the wrong tool. We keep bringing philosophy to a biology fight.

Growing up, this was the riddle that made you sound wise at the dinner table. Whoever asked it had the upper hand. Whoever tried to answer it went round and round like a danfo driver hunting for a parking spot at Ojuelegba. LOL.

So I did what any recovering engineer would do. I went looking for data. Buckle up, there are three twists, and the last one is the one that should change how you see the whole thing.

First, agree on the spec

Years around pipelines and pressure vessels taught me one sacred rule: before you argue about a problem, agree on the specification. Half the arguments in life are two people answering two different questions and shouting past each other.

This riddle is actually two questions wearing one agbada. Question one: did eggs exist before chickens? Question two: did the first chicken egg come before the first chicken? Answer the first one and you will be done before your tea goes cold. The second is where the real fight lives.

Twist one: the egg is ancient, the chicken is a newcomer

Eggs are old. Very old. Fish laid eggs. Amphibians laid eggs. Dinosaurs laid eggs, and we have dug up their fossilised clutches to prove it. Animals were reproducing through fertilised eggs hundreds of millions of years before anything with feathers crossed any road.

The chicken, on the other hand, is a teenager in evolutionary time. A major 2022 study in the Proceedings of the National Academy of Sciences traced the earliest unambiguous domestic chicken bones to Ban Non Wat, a Neolithic site in central Thailand, dated to roughly 1650 to 1250 BCE. The researchers believe rice and millet farming lured the wild red junglefowl out of the trees and into human settlements, and the rest, as they say, is pepper soup.

Except it wasn’t. Not at first. The same research programme found that early chickens seem to have been kept as cultural icons long before they made it to the dinner table. Imagine that. The chicken started out as a celebrity, not a Sunday stew.

So on the broad definition, case closed: the egg wins by a few hundred million years. But you and I both know that’s cheating. The reel was not asking about dinosaur eggs.

Twist two: the first chicken hatched from an egg laid by a non-chicken

Here’s the science that settles question two, and it rests on one simple fact. Every living thing carries a genetic blueprint, its DNA, and a new individual’s combination is set at one precise moment: when sperm meets egg and the fertilised cell forms. Not before. Not after. A bird does not change species halfway through its life, no matter how many motivational reels it watches.

Genetic studies point to a specific subspecies of red junglefowl in Southeast Asia, Gallus gallus spadiceus, as the most likely ancestor of the domestic chicken. Over many generations living alongside humans, tiny genetic changes piled up. At some point, two birds that were almost chickens mated. Their fertilised egg carried a combination of genes that, for the very first time, we would call “chicken.”

That egg hatched. Out walked the first chicken.

The first chicken egg was laid by a bird that wasn’t quite a chicken.

Now, in fairness, “the first chicken” is a convenient fiction. Evolution doesn’t work with a light switch; it works with a dimmer. When exactly does a boy become a man? There’s no single birthday when the beard arrives and the wisdom follows. Ask any Nigerian mother and she will tell you plainly: the day he starts paying his own rent. LOL.

But wherever you draw that line, the logic holds. The bird on the chicken side of the line came out of an egg laid by a bird on the other side. Egg first.

Twist three: the scientists who said “chicken”

Fairness demands that I hear the opposition. In 2010, researchers at the Universities of Sheffield and Warwick made headlines around the world with a bold claim: the chicken came first. Their evidence was a protein called ovocleidin-17, or OC-17, found in the hen’s ovaries. Using a supercomputer in Edinburgh, they watched it clamp onto particles of calcium carbonate, kick-start their transformation into calcite crystals, then let go and repeat the job. That speed is how a hen builds roughly six grams of shell every 24 hours.

Their logic: no chicken, no OC-17. No OC-17, no chicken eggshell. Therefore, chicken first. One of the lead researchers even called it scientific proof.

Impressive work. But this is where the engineer in me squints. The study explains how a modern chicken builds a modern shell. It tells you nothing about where the first chicken came from. It’s like studying the machines in a factory today and declaring you now know who built the first factory. Even the university’s own release called it a partial answer, and the real prize was materials science: learning from nature how to design stronger materials. The headline writers simply ran with the chicken.

The plot twist nobody saw coming

Just when you thought it was settled, two recent studies pulled the rug further back.

In 2023, a team from the University of Bristol and Nanjing University analysed 51 fossil species and 29 living ones and concluded that the very first amniotes, the shared ancestors of reptiles, birds and mammals, may have relied on extended embryo retention, keeping the developing young inside the mother, rather than the classic hard-shelled egg. In other words, even the famous shelled egg had to earn its place over time.

Then in 2024, scientists at the University of Geneva published a study in Nature on a single-celled organism called Chromosphaera perkinsii, first discovered in marine sediments near Hawaii in 2017. Once it reaches its maximum size, it stops growing and divides into a multicellular colony that looks remarkably like the early stages of an animal embryo. Its lineage diverged from animals more than a billion years ago, far older than the first animals. The finding suggests that nature may have had some of the genetic tools for embryo-like development long before it made chickens.

Think about that. Before the chicken, before the dinosaur, before the fish, the programme for the egg was already being written.

My verdict: the egg. Conclusively.

Let me land this plane. If you mean any egg, the egg wins by hundreds of millions of years. If you mean the chicken egg, the egg still wins, because the first chicken was sealed inside an egg laid by a bird that was not yet a chicken. And if you go all the way back, the molecular machinery for embryo-like development predates animals altogether. The only argument for the chicken describes how today’s hens make today’s shells. That is a lovely piece of chemistry. It is not an answer to the riddle.

Need I say more? The egg came first.

And here’s why I care beyond the trivia. Every “chicken” we chase in life, the promotion, the business, the breakthrough, the big audacious move, started out as an egg. Something small, fragile and unremarkable that somebody was patient enough to incubate. My own career has been a string of phone calls that looked like nothing at the time. The trouble is, most of us want the chicken without sitting on the egg.

Every chicken you’re chasing started as an egg somebody was willing to sit on.

Sources

• Peters, J. et al. (2022), “The biocultural origins and dispersal of domestic chickens”, PNAS 119(24), e2121978119.
• Best, J. et al. (2022), “Redefining the timing and circumstances of the chicken’s introduction to Europe and north-west Africa”, Antiquity 96(388), 868-882.
• Freeman, C. L. et al. (2010), “Structural Control of Crystal Nuclei by an Eggshell Protein”, Angewandte Chemie International Edition 49(30), 5135-5137.
• Jiang, B. et al. (2023), “Extended embryo retention and viviparity in the first amniotes”, Nature Ecology & Evolution 7, 1131-1140.
• Olivetta, M. et al. (2024), “A multicellular developmental program in a close animal relative”, Nature 635, 387-394.