Did the Chicken or the Egg Come First? Scientists May Have Finally Solved the Mystery

What came first, the egg or the chicken? The dilemma has caused everyone, from classroom teenyboppers to leaders, to scratch their heads, even prompting an Indonesian man to stab his friend. The age-old circular reasoning stems from the idea that chickens hatch from eggs and eggs are laid by chickens. So who came first? After almost a century, the ancient riddle has finally been solved. The egg is the winner. Dozens of scientists across the world have verified this. Long before chickens emerged into existence, nature already had essential genetic tools to “create eggs,” as researchers from the University of Geneva said in a study published in the journal Nature.

The researchers from Geneva studied some fossils of a prehistoric single-celled organism Chromosphaera perkinsii which they found in Hawaii. The creature dated billions of years ago, as the Museum of Science (@museumofscience) also explained on Instagram. In the study, they proposed that this creature underwent cell division to produce something that resembled eggs. Eggs were there long before fish swam in the seas or monstrous critters crawled out of the waters. They were not chicken eggs, but they were eggs, laid by creatures like dinosaurs. In an interview with The Guardian, Jules Howard, the author of Infinite Life: A Revolutionary Story of Eggs, Evolution, and Life on Earth said that this “chicken or egg” question should be approached in a more specific manner.

“A more thought-provoking way of approaching the question is to ask: ‘What came first, the egg or the egg tube?’” he told the outlet. Essentially, there had to be an egg tube that would produce eggs but this egg tube might not necessarily belong to chickens. “How could there be an egg if there were no egg tubes?” Howard reflected. “Egg tubes abound across the animal kingdom. From egg tubes that leak milk from their walls like the eyes of holy statues (some flies), to egg tubes that paste cement-like glue all over the eggs, so that they can be stuck onto human hair (head lice). There are egg tubes where embryos wrestle and fight to the death (some sharks), egg tubes inhabited by blood-sucking placentae (some mammals), egg tubes flanked by paired vaginas,” he elaborated.

The zoologist explained that while chickens are about 600 million years old, egg-laying species like dinosaurs, reptiles, and birds are considered billions of years old. So clearly, eggs came before the chickens, but they were not chicken eggs. “If you think of an egg as something with a hard shell that you can crack with a spoon, then the egg did arrive long before chickens,” Howard told the outlet.

In 2023, some researchers from researchers from Nanjing University and the University of Bristol led another study in which they analyzed 51 fossil species and 29 living species categorized as oviparous - laying hard or soft-shelled eggs, according to a press release. A researcher, Michael Benton, described that even before 320 million years ago when amniotes came into existence, tetrapods had already started to develop limbs from fishy fins. Later, amniotes popped with features that allowed them to crawl out of the waters to reproduce.

Biologists discovered fossils of many lizards and snakes that laid their eggs outside their water ponds. These reptilian mammals did “embryo retention” until the temperature outside was warm enough and food supplies were rich. But at this time, when chickens weren’t yet part of the evolution cycle, their distant ancestors like dinosaurs and reptiles were already laying eggs.

During the Jurassic era, around 200 million years ago, dinosaurs laid eggs. The only difference was that their eggs weren’t like the typical hard-shelled eggs loaded with nutritious yolks. They were more like porcelain and less like a banana peel. Some of them were of the thickness of “human hair,” as Koen Stein, a paleontologist who studied dinosaur eggs, told Live Science. So the egg definitely came first, unless once restates the question, what came first – the chicken or the chicken’s egg?