Age-old mystery solved: No more chicken or egg debate; scientists reveal who came first

Technically, an egg is a membrane-bound container where an embryo develops into an independent life. (Image: Canva)

The age-old question of whether the chicken or the egg came first has puzzled minds for centuries. It’s a curious riddle that has sparked debate, humour, and even scientific investigation. To uncover the answer, we must delve into the fascinating history of eggs and the evolutionary journey of chickens, tracing back millions of years.

Eggs are widespread throughout the animal kingdom. Technically, an egg is a membrane-bound container where an embryo develops into an independent life. Eggs have been around since the evolution of the first amniotes, many millions of years ago. Early animals laid eggs in water, ensuring they didn’t dry out.

A crucial evolutionary step saw the emergence of amniotic eggs. These eggs developed three extra membranes: the chorion, amnion, and allantois. Together, they formed a complete life support system for embryos. This breakthrough enabled animals to lay eggs on land, offering embryos protection and nourishment without needing water.

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The first chicken’s arrival
According to the Australian Academy of Science, the first chicken emerged through genetic mutation. Two proto-chickens mated, passing on their DNA to create the first chicken. Genetic mutations occurred during this process, leading to the development of the very first chicken. This mutation was replicated in every cell as the chicken embryo grew.

Research suggests that amniotic eggs appeared roughly 340 million years ago, while chickens only evolved around 58,000 years ago. It’s reasonable to conclude that eggs predate chickens, as these eggs allowed various animal embryos to develop long before chickens existed.

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However, chickens have a protein that plays a critical role in forming their eggs. This protein, called ovocleidin-17 (OC-17), is only found in chicken ovaries. Scientists argue that chickens must have come first because OC-17 is essential for forming eggshells, which are built within 24 hours.

The age-old debate
So, where does this leave the question? While eggs predate chickens, the specific formation of chicken eggs requires chickens for OC-17 production. Ultimately, chickens and their eggs are mutually dependent, making the answer far from simple.

Today’s eggs differ greatly from those produced by early birds. Industrialised farming methods focus on efficiency, with hens in controlled environments. Modern eggs meet strict safety standards, with options like free-range or organic eggs. In contrast, proto-eggs came from hens living freely, resulting in smaller production and different nutritional values.

Is eating chicken or eggs healthier?
Both chicken and eggs offer rich nutritional benefits. Chicken provides lean protein, vital vitamins like B3, and essential minerals, ideal for muscle growth and low-calorie diets. Eggs, meanwhile, deliver balanced protein, vitamins D and B12, and healthy fats. Eggs also contain antioxidants, supporting eye health. The choice between chicken and eggs ultimately depends on dietary preferences and needs.