Explain how comes first egg or hen

This question seems impossible, but science gives us a clear answer. Hens are birds, and all birds lay eggs to reproduce.

• The answer: the egg came first.

But here is the key: eggs existed millions of years before chickens did. Fish evolved first, then amphibians, then reptiles—all laying eggs.

• Fish laid eggs 500 million years ago.

Dinosaurs laid eggs too, long before any bird existed.

Birds evolved from small dinosaurs around 150 million years ago. Chickens are a domesticated bird, created by humans only 8,000 years ago.

• Birds: evolved from dinosaurs.

So the first chicken came from an egg laid by a bird that was almost, but not quite, a chicken. Over many generations, tiny mutations changed the bird's DNA until a new species emerged.

• Mutation: parent bird laid first true chicken egg.

Quick quiz: which came first in Earth's history—fish eggs or dinosaur eggs? The egg came first because eggs existed for hundreds of millions of years before chickens evolved.

• Answer: the egg, by far.