~3.8 billion years agoReputable source · 2 sourcesDebated
The Origin of Life
On the timeline · around ~3.8 billion years ago · Archean
What happened
Life arose on the early Earth not long after the planet became habitable. The oldest possible traces — microfossils in ancient seafloor rocks of Quebec's Nuvvuagittuq belt and carbon signatures and stromatolite-like structures in Greenland — date to roughly 3.7–3.8 billion years ago, with some claims reaching further back still.
Why it matters
The origin of life is the root of the entire tree of living things — every organism that has ever existed descends from these first cells.
How we know
The earliest biosignatures are debated among scientists; the exact timing and identity of the first life remain contested.
The earliest evidence for life is contested and its dating uncertain, ranging from ~3.5 to over 4 billion years.
Sources
- NASA Astrobiology. Oldest evidence for early life on Earth dated to at least 3.77 billion years · Reputable source
- Natural History Museum. The origin of life on Earth · Reputable source