In 2015, possible 'remains of biotic life' were found in 4.1 billion-year-old rocks in Western Australia.

The earliest evidence of life comes from biogenic carbon signatures and stromatolite fossils discovered in 3.7 billion-year-old metasedimentary rocks from western Greenland. These currently living species represent less than one percent of all species that have ever lived on Earth. Approximately 1 trillion species currently live on Earth of which only 1.75–1.8 million have been named and 1.8 million documented in a central database. The similarities among all known present-day species indicate that they have diverged through the process of evolution from a common ancestor.

Plants and the Late Devonian wood crisis.

Deuterostomes and the first vertebrates.

Sexual reproduction and multicellular organisms.

Chromatin, nucleus, endomembrane system, and mitochondria.

Environmental and evolutionary impact of microbial mats.

Although there is some evidence of life as early as 4.1 to 4.28 Ga, it remains controversial due to the possible non-biological formation of the purported fossils. Earth formed about 4.5 billion years ago (abbreviated as Ga, for gigaannum) and evidence suggests that life emerged prior to 3.7 Ga.

The history of life on Earth traces the processes by which living and fossil organisms evolved, from the earliest emergence of life to present day.

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