Which came first, the chicken or the egg? This is one of life’s ___1___ questions and people have been debating about it for thousands of years. Now scientists believe they have solved this ___2___. Researchers from Sheffield and Warwick Universities in England discovered the answer ___3___. They used a super computer to observe the shell-making process while a new shell was ___4___. Then they found one protein called OC17 that is ___5___ for forming eggshell.