Earth's History on a 24-Hour Clock, Part 2: Life Gets Complicated

For billions of years, every living thing on Earth was a single microscopic cell. Then one microbe swallowed another and didn't digest it. From that partnership came complex cells, bodies, sex, a second Snowball Earth, the strange Ediacaran "garden", and finally the Cambrian explosion: animals with legs, shells, jaws and eyes. On our 24-hour clock of Earth's history, this episode runs from noon to ten past nine at night. Episode 2 of "From Dust to Us". Previous: How Earth Was Made · Next: Out of the Water CHAPTERS 0:00 Swallowed, not digested 0:25 Back on the clock 0:49 The boring billion 1:21 Mitochondria 2:26 Bodies 2:52 Sex 3:20 Snowball Earth, again 3:47 The Ediacaran garden 4:26 The Cambrian explosion 4:57 Weird wonders 5:42 Why then? 6:23 Our ancestor 6:45 Next time SOURCES Endosymbiotic origin of mitochondria and chloroplasts Early eukaryote fossils, ~1.6–1.8 billion years ago (still debated) Bangiomorpha pubescens, ~1.05 billion years ago, Arctic Canada (Butterfield 2000; Gibson et al. 2018) Cryogenian Snowball Earth glaciations, ~720–635 million years ago Dickinsonia cholesterol biomarkers (Bobrovskiy et al., Science, 2018) Cambrian explosion from ~539 million years ago; Burgess Shale and Chengjiang fossils