Table 1.

Data for Evolutionary Transition Timing and Biosphere Start/End Dates

Transition	Date, Gya	Source	Method
Abiogenesis	>4.10 ± 0.01	Bell et al. (2015)	Carbon isotope ratio
Abiogenesis	3.9	Betts et al. (2018)	Molecular clock
Abiogenesis	>3.86 ± 0.01	Mojzsis et al. (1996)	Carbon isotope ratio
Abiogenesis	>3.77–4.28	Dodd et al. (2017)	Microfossils, isotope ratio
Abiogenesis	>3.5	Awramik (1992)	Microfossils, stromatolites
Cyanobacteria	<10 Ma	Lazcano and Miller (1994)	Molecular evolution model
Eukaryotes	<1.84	Betts et al. (2018)	Molecular clock
Eukaryotes	>1.87–1.68	Parfrey et al. (2011)	Molecular clock
Sex	>1.2	Butterfield (2000)	Fossils of red algae
Intelligence	≈0	Pääbo (2014)	Oldest artwork

Boundary	Timing	Source	Method
Oceans form	4.40 Gya	Peck et al. (2001)	Oxygen isotope ratio
Oceans form	4.3–4.2 Gya	Cavosie et al. (2005)	Oxygen isotope ratio
Biosphere ends	0.8–1.2 Ga	Franck et al. (2006)	Climate model
Biosphere ends	0.9–1.5 Ga	Caldeira and Kasting (1992)	Climate model
Biosphere ends	≈1.0 Ga	Kasting (1988)	Climate model
Biosphere ends	1.8–3.3 Ga	Rushby et al. (2013)	Climate model

Biosphere end dates are given for eukaryotic life. Extremophiles may persist beyond the dates given.