A chicken conundrum

It is an age-old question that has perplexed adults and childrens alike and also vexed scientists and philosophers the world over since ancient times: which came first, the chicken or the egg?

I always thought that if you started with two non-chicken parents, and they produced offspring which differed because of a genetic mutation, then this is how you would get the first chicken. The mutation would mean that the offspring were chickens and the parents were not, so it’s simple, the egg came first, right? Wrong!

It seems that after much debate and research, British scientists claim to have finally come up with a definitive answer as a consequence of other research. Following the publication of the scientific paper, Structural Control of Crystal Nuclei by an Eggshell Protein in 2010, researchers announced that they had answered, by accident, this very question.

Teams from the Universities of Warwick and Sheffield were looking at a protein called ovocledidin-17 in order to find out more regarding how animals make eggshell. Ovocledidin-17 is thought to speed up the production of eggshell within an animal so that in around 24-28 hours an egg is ready to be laid.

We tend to forget that chickens perform an amazing process each time they make an egg; when you crack into your boiled egg in the morning, you are looking at one of the most amazing materials in the world. Eggshell is incredibly strong yet very lightweight and, despite our technology, we cannot manufacture anything close to it. By understanding how birds make their eggs, the scientists sought to learn how we can make similar products. The team chose to study chicken eggs simply because the proteins they contain are simple to look at.

The researchers fed their data into the UK Science Research Council’s computer based in Edinburgh (rather reassuringly called HECToR, short for High End Computing Terascale Resource), and were able to simulate the process of biomineralization - the production of minerals or solid materials inside animals.

The results showed that in chickens, Ovocledidin-17 acts as a ‘builder’ mechanism, allowing one microscopic piece of shell to be placed on top of the other. It initiates this building, and accelerates the crystallization process before going off to start on another part of the egg. The protein therefore speeds up the development of the hard shell, which we know is essential for protecting the delicate yolk and fluids while the chick grows inside the egg.

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Now here’s the really the surprising bit. As a consequence of the investigation, they also found that the egg can’t be produced without this protein, and established that it is only present in a chicken’s ovaries.

This in turn led to their logical conclusion that the chicken must have come first to have the protein in order to produce the egg!

So with this question answered, that only leaves us to ponder why the chicken crossed the road…?