By Daily Mail Reporter
It has been the ultimate philosophical and scientific mystery for centuries - until now, that is.
Scientists yesterday claimed to have cracked the riddle of whether the chicken or the egg came first.
The answer, they say, is the chicken. Researchers found that the formation of egg shells relies on a protein found only in a chicken's ovaries.
Therefore, an egg can exist only if it has been inside a chicken.
The protein - called ovocledidin-17, or OC-17 - acts as a catalyst to speed up the development of the shell.
This hard shell is essential to house the yolk and its protective fluids while the chick develops inside.
Scientists from Sheffield and Warwick universities used a super computer to 'zoom in' on the formation of an egg.
The computer, called HECToR and based in Edinburgh, revealed that OC-17 is crucial in kick-starting crystallisation - the early stages of the creation of a shell.
The protein coverts calcium carbonate into calcite crystals which make up the shell.
Calcite crystals are found in numerous bones and shells but chickens form them quicker than any other species - creating six grams (0.2oz) of shell every 24 hours.
Dr Colin Freeman, from Sheffield University's Department of Engineering Materials, said: '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.
'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.
'It's very interesting to find that different types of avian species seem to have a variation of the protein that does the same job.'
Professor John Harding, from the same department, said the discovery could have other uses.
'Understanding how chickens make egg shells is fascinating in itself but can also give clues towards designing new materials and processes,' he said.
'Nature has found innovative solutions that work for all kinds of problems in materials science and technology - we can learn a lot from them.'
The discovery was revealed in the paper Structural Control Of Crystal Nuclei By An Eggshell Protein.