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History of life

Evolutionary History Of Life

Evolutionary history of life on earth traces the processes by which living and fossils organisms evolved, from the earliest emergence of life ''to the present. Earth formed about 4.5 billion years (Ga) ago and evidence suggests life emerged prior to 3.7 Ga. ( Although there is some evidence of life as early as 4.1 to 4.28 Ga, it remains cantroversial due to the possible non -biological formation of the purported fossils.''

The similarities among all known present-day species indicate that they have diverged through the process of evolution from a common ancestor. Approximately 1 trillion species currently live on earth of which only 1.75 - 1.8million have been named and 1.6 million documented in a central database. These currently living species represent less than one percent of all species that have ever lived on earth.