The early universe had no stars, no planets, and no living organisms. Then, step by step, entirely new things began to appear. Stars were forged from atoms of hydrogen and helium, new chemical elements were created inside dying stars, planets and moons formed from blobs of ice and dust using these new chemical elements, and the first living cells evolved in the rich chemical environments of rocky planets. We humans are very much part of this story, because we are products of the evolution and diversification of life on planet Earth, but in the course of our brief but remarkable history, we
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