Which Came First: The Chicken or the Egg?

It is finally time to put to rest the eternal question: which came first, the chicken or the egg? Now, I should be clear. This is not a deep and profound philosophical examination of beginnings and ends. This is a very simple, short, factual analysis of chickens, their predecessors, and their offspring.

Let’s clear up some definitions to start. The word “chicken” means an organism belonging to the species “gallus gallus domesticus” - in other words, a domestic chicken, like the ones on a farm. The word “egg” means a chicken egg that hatches a “gallus gallus domesticus,” not any arbitrary egg.

Now, species evolve from other species. I evolved from a single-celled organism. You evolved from a single-celled organism. However, there were many steps in between: the single-celled organism turned into an aquatic organism, which turned into an amphibious organism, which became a land-dwelling organism, which then started walking on two legs, and so on, until we get to you and me. It’s the same with chickens, except at some point the human line branched off from the chicken line.

To get to the chickens we have today, we started with the red junglefowl, a species that holds many similarities to a chicken, like the fact that they hatch eggs. How exactly did junglefowl become chickens? To start off, say we have a bunch of red junglefowl. Naturally, some of them will breed, producing a bunch more young junglefowl. However, because of naturally occurring genetic mutations, maybe some of these junglefowl are a little plumper than others and have slower metabolisms. Now, let’s say that the food supply has decreased a bit for the junglefowl. Which type is more likely to survive? The ones with slower metabolisms that make food last longer, or the ones that burn through food quickly? The ones with slow metabolisms, of course!

Due to the “slow” junglefowl’s better survival rates, they are more likely to reproduce. When they do, they pass on their small genetic mutations, creating more junglefowl that have slow metabolisms. Eventually, most of the species will be characterized by a slow metabolism. And eventually, more and more mutations will be introduced -- e.g., longer necks, louder calls, and brighter feathers, so that after millions of years and generations, the species look quite different from the original.

This is basically what happened during the transition from junglefowl to chickens: mutations simply piled up to create the particular characteristics we see in chickens today. That means that somewhere along the line, two junglefowl produced a chicken egg with exactly the right set of mutations from which hatched a chicken. Which means -- you guessed it -- the egg came first!

Of course, this is probably an unsatisfying conclusion because it doesn’t really answer the philosophical question, and that’s the part that really bothers people. So I’ll just quote a little piece of wisdom from Harry Potter and the Deathly Hallows that addresses this dilemma perfectly: 

"Which came first, the phoenix or the flame?" 

"... I think the answer is that a circle has no beginning" (587).