Asked by: Alan Healy, France
Eggs are much older than chickens. Dinosaurs laid eggs, the fish that first crawled out of the sea laid eggs, and the weird articulated monsters that swam in the warm shallow seas of the Cambrian Period 500 million years ago also laid eggs. They weren’t chicken’s eggs, but they were still eggs.
So the egg definitely came first. Unless you restate the question as ‘which came first, the chicken or the chicken’s egg?’ Then it very much depends on how you define a chicken’s egg. Is it an egg laid by a chicken? Or is it an egg that a chicken hatches from? Chickens are the same species as the red jungle fowl of Southeast Asia, although they were probably hybridised with the grey jungle fowl when they were domesticated 10,000 years ago.
But it doesn’t matter; at some point in evolutionary history when there were no chickens, two birds that were almost-but-not-quite chickens mated and laid an egg that hatched into the first chicken. If you are prepared to call that egg a chicken’s egg, then the egg came first. Otherwise, the chicken came first and the first chicken’s egg had to wait until the first chicken laid it.