What came first, the chicken or the egg?

The question of whether the chicken or the egg came first is largely resolved through the lens of evolutionary biology.

General Eggs

Eggs are significantly older than chickens. The first hard-shelled eggs, known as amniotic eggs, which could be laid on land, appeared around 312-325 million years ago during the Carboniferous period. These eggs were laid by early amniotes, which include the ancestors of modern mammals, reptiles, and birds134.

Chicken-Specific Eggs

When focusing specifically on the chicken, the answer is still that the egg came first. Chickens evolved from a subspecies of red jungle fowl (Gallus gallus) around 50 million years ago, and were domesticated by humans between 1650 B.C. and 1250 B.C.123.

The process involves a proto-chicken laying an egg that contained genetic mutations sufficient to make the hatched bird distinct from its parents, thus marking the emergence of the modern chicken. Therefore, it was an egg laid by a bird that was almost, but not quite, a chicken that hatched into the first true chicken124.

In summary, the egg definitively came before the chicken, both in the broader context of evolutionary history and in the specific case of the emergence of the modern chicken.