Why oxygen alone cannot explain the Cambrian explosion

More oxygen helped complex animals, but cannot explain them alone

More oxygen may have helped larger and more complex animals meet their energy needs and build hard body parts. But meter-long organisms already existed before the Cambrian explosion. Rising oxygen alone therefore cannot explain the later burst of animal diversity.

One European war may have erased more than a century of population growth

The Thirty Years' War devastated large parts of Central Europe between 1618 and 1648. Fighting, famine and disease caused enormous population losses. According to one historical estimate, the Holy Roman Empire did not regain its prewar population until around 1750—more than a century after the fighting ended.

Writing is only one form of language

Many linguists treat spoken and signed languages as more basic forms of language than writing. Humans used speech long before writing existed, children learn language before they learn to write, and writing does not capture every feature of speech or signing.

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Why oxygen alone cannot explain the Cambrian explosion

More oxygen helped complex animals, but cannot explain them alone

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