Question
What came first on earth ,Hen Roster or egg.

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The question of which came first—the chicken or the egg—has been a subject of philosophical and scientific debate for centuries. From a biological and evolutionary perspective, here's the most widely accepted explanation:

Evolutionary Perspective:

1. Eggs Came First:
   • Prehistoric Eggs: Eggs have existed for millions of years, long before birds evolved. Reptiles, amphibians, and certain fish were laying eggs long before the first chickens appeared.
   • Genetic Mutation: The first chicken (hen or rooster) likely evolved from a bird that was not quite a chicken. This proto-chicken laid an egg, and through genetic mutation during reproduction, the egg contained the first true chicken. Thus, the egg containing the first true chicken came before the chicken itself.

Scientific Consensus:

• Proto-chickens: Birds closely resembling chickens existed before the first modern chicken. Through a process of genetic mutations and natural selection, a mutation occurred in the reproductive cells of these proto-chickens, leading to the birth of the first true chicken from an egg.
• Ovocalycin-17: Research suggests that a protein called ovocalycin-17, which is crucial for eggshell formation, is found only in the ovaries of chickens. This discovery implies that eggshell formation is unique to chickens, supporting the idea that the egg (as a structure) existed before the modern chicken.

Conclusion:

From an evolutionary standpoint, the egg came first. The reasoning is that the first true chicken emerged from a genetic mutation in an egg laid by a bird that was not quite a chicken.

Sources:

1. Science Focus
2. BBC - Earth

This explanation blends both the evolutionary timeline and the genetic evidence to provide a comprehensive answer to this age-old question.