Which came first, the egg or the hen?

This famous thought problem has puzzled many, but I hope my answer will be satisfactory to you.

When we focus on the hen, specifically, this question is quite difficult to answer. It would depend on how we determine who the egg belongs to, and at what point we can say with certainty that a new species of poultry bird has come into existence.

Let's imagine a scenario between Bird A and her offspring, Bird B. In this scenario, we'll also consider Species 1 and Species 2 as two distinct species based upon their characteristics. Bird A is a hen that exemplifies some transitional characteristics between two species, but still falls close enough into the category for Species 1. Depending on the male bird she mates with, she may have offspring that fall more closely into the category of Species 2. Let's imagine that Bird B is the offspring of Bird A, and while Bird A has been classified as Species 1, Bird B can be classified as Species 2.

As if that weren't tricky enough, let's consider ownership of the egg. The egg itself isn't a body part and so can't really be considered a distinct genetic part of either mother or baby. With that in mind, who does it belong to, and what does it mean for our question? The egg either belongs to Bird A or Bird B, and depending on which, we might say that either the egg or hen came first. Here are our two possibilities:

• The egg belongs to Bird A, the mother. When Bird B hatches, this bird is the first of Species 2. In this case, the hen came before the egg, because Bird B will lay the first eggs of Species 2. Of course, all of this is dependent upon Bird B being born a female poultry bird and thus a hen.


• The egg belongs to Bird B, who hatches from the egg. In this case, the egg existed prior to Bird B and has come first. This scenario is not necessarily dependent upon the sex of Bird B.

Now let's focus on the egg rather than the hen. I hope that this offers a much simpler answer to your question. Eggs as a reproductive unit have existed for much longer than birds, so technically the egg came before the hen! In fact, birds evolved from some lizard-like species of dinosaurs who laid eggs. Even farther back in our evolutionary history, many sea creatures laid eggs, but not in the hard-shell form we associate with hens. Any way you wish to look at it, eggs as a reproductive unit date to far earlier than any hen. It is only when we focus on the species of the hen and its related eggs that the question need be so complex.