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1,174,289 views | Peter Ward • TED2008

A theory of Earth's mass extinctions

Asteroid strikes get all the coverage, but "Medea Hypothesis" author Peter Ward argues that most of Earth's mass extinctions were caused by lowly bacteria. The culprit, a poison called hydrogen sulfide, may have an interesting application in medicine.

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This talk was presented at an official TED conference. TED's editors chose to feature it for you.

Asteroid strikes get all the coverage, but "Medea Hypothesis" author Peter Ward argues that most of Earth's mass extinctions were caused by lowly bacteria. The culprit, a poison called hydrogen sulfide, may have an interesting application in medicine.

This talk was presented at an official TED conference. TED's editors chose to feature it for you.

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Peter D. Ward studies life on Earth -- where it came from, how it might end, and how utterly rare it might be.