On this date, American paleobotanist Elso S. Barghoorn of Harvard reported the discovery of Precambian spherical one-celled alga-like microfossils (named Eobacterium isolatum, which means “solitary dawn bacteria”) 3.4 billion years old, Earth’s earliest life forms. Barghoorn, with J. William Schopf, studied the 3.2 billion year old chert (a flintlike or quartz-like rock) of the Fig Tree formation in Transvaal, South Africa. Rubidium and strontium ratios in the chert suggested an age of over 3 billion years. The fossils are examples of prokaryotes, unicellular organisms that lack a nucleus and have a distinctive cell wall containing organic chemicals.
- Barghoorn, E.S., Schopf, J.W. (1966). Microorganisms three billion years old from the Precambrian of South Africa. Science, 152(3723), 758-763. DOI: 10.1126/science.152.3723.758