For billions of years, bacteria and other single-celled organisms were the only life on Earth.
Notes on verification
Confirmed by multiple independent, authoritative sources including AMNH, Natural History Museum UK, NASA Astrobiology, and Smithsonian, all consistent with a multi-billion-year period of single-celled-only life on Earth.
Sources
- Interesting facts about Earth from Harvard paleontologist (news.harvard.edu)
- https://naturalhistory.si.edu/education/teaching-resources/life-science/early-life-earth-animal-origins (naturalhistory.si.edu)
- https://www.amnh.org/exhibitions/permanent/planet-earth/how-has-the-earth-evolved/life-explodes (amnh.org)
- https://www.nhm.ac.uk/discover/origin-of-life-on-earth.html (nhm.ac.uk)
- https://astrobiology.nasa.gov/news/how-did-multicellular-life-evolve/ (astrobiology.nasa.gov)