Which Came First, the Chicken or the Egg? 3

It’s an age old conundrum- and one that yours truly, textbook rental company, Chegg, modeled its name after.  Gizmodo thought it would tackle this question and posted an intriguing article addressing “Which came first, the chicken or the egg?”.

The original article contends that “It had long been suspected that the egg came first, but now we have the scientific proof that shows that in fact the chicken came first,” says Dr. Colin Freeman, from Sheffield University. Scientists at Sheffield University and Warwick University analyzed chicken egg shells, discovering a protein (called ovocledidin-17) that speeds up shell development. That same protein is found in a chicken’s ovaries, which leads them to believe the chicken must have come first.

However, the update in the article states otherwise.  A biologist writing for ScienceBlogs explained that the protein they found is a specific molecule that has multiple purposes with one key property- it binds calcium. Birds have these proteins to regulate egg shell formation and each bird has a different one- a chicken has oveocledidin, geese have ortholog, ansocalcin and on and on. Bottom line (in scientific jargon): “You simply can’t make the conclusion the reporter was making [in the original article]. The species ancestral to Gallus gallus laid eggs, the last common ancestor of all bird’s laid eggs, the reptiles that preceded the birds laid eggs…the appearance of egg laying was not coincident with the evolution of ovocleidin.” So the very first chicken that gained the protein called ovocleidin did so by mutation, from a prior protein which also hatched from an egg! Therefore, it is not safe to assume that the chicken came before the egg, especially since species have been laying eggs long before the chicken was in existence.

Which leads us back to the initial question…

What do you think came first, the CHICKEN or the EGG?