This from Stuff.co.nz:
British scientists believe they have cracked the answer to the age-old question of which came first, the chicken or the egg?
Researchers have found that a protein called ovocleidin (OC-17) is crucial in the formulation of eggshells, and it is produced in the pregnant hen’s ovaries, the Daily Express reports.
Therefore, the answer to the conundrum must be that the chicken came first.
Using a high-tech computer to look at the molecular structure of a shell, the team of scientists from the Universities of Sheffield and Warwick found that OC-17 acts as a catalyst, kick-starting the conversion of calcium carbonate in the chicken’s body into calcite crystals.
They make up the hard shell that houses the yolk and its protective fluids while the chick develops.
“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,” said Dr Colin Freeman, from Sheffield University.
“The protein had been identified before and it was linked to egg formation but by examining it closely we have been able to see how it controls the process.”
But the researchers have not yet got an answer to how the protein-producing chicken existed in the first place.
I may have more to say about this later… I don’t quite see how this is “proof” that the chicken came first.
Update: Here’s PZ Myer’s take on this. In a nutshell:
You simply can’t make the conclusion the reporter was making here. The species ancestral to Gallus gallus laid eggs, the last common ancestor of all birds laid eggs, the reptiles that preceded the birds laid eggs…the appearance of egg laying was not coincident with the evolution of ovocleidin. The first chicken that acquired the protein we call ovocleidin now by mutation of a prior protein also hatched from an egg.