# A theory of Earth's mass extinctions

- Institution: TED
- Department: TED2008
- Speaker: Peter Ward
- Year: 2008
- Level: For everyone
- Language: English
- Subjects: Medicine and health, Earth and environment, Astronomy and space, History
- Source: [TED](https://www.ted.com/talks/peter_ward_a_theory_of_earth_s_mass_extinctions)
- Licence: [CC BY-NC-ND 4.0](https://creativecommons.org/licenses/by-nc-nd/4.0/) (Non-commercial use only, and no changed versions.)
- Who can watch: Teens profiles and older (sources give no ratings; placed by Invisible Network from the source's own words)

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.

## Lectures

1. [A theory of Earth's mass extinctions](https://invisiblenetwork.ai/learn/ted/peter_ward_a_theory_of_earth_s_mass_extinctions/37f2db0d69aa), 20 min (TED's player)