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More than 99 percent of all species that ever lived (over five billion) [1] are estimated to be extinct. [2] [3] Estimates on the number of Earth's current species range from 10 million to 14 million, [4] with about 1.2 million or 14% documented, the rest not yet described. [5]
The history of life on Earth traces the processes by which living and extinct organisms evolved, from the earliest emergence of life to the present day. Earth formed about 4.5 billion years ago (abbreviated as Ga, for gigaannum) and evidence suggests that life emerged prior to 3.7 Ga. [1] [2] [3] The similarities among all known present-day species indicate that they have diverged through the ...
The age of Earth is about 4.54 billion years; [7] [33] [34] the earliest undisputed evidence of life on Earth dates from at least 3.5 billion years ago according to the stromatolite record. [35] Some computer models suggest life began as early as 4.5 billion years ago. [36] [37] The oldest evidence of life is indirect in the form of isotopic ...
Date Event 2.8–2.0 Ma Early Homo appears in East Africa, speciating from australopithecine ancestors. The Lower Paleolithic is defined by the beginning of use of stone tools. Australopithecus garhi was using stone tools at about 2.5 Ma. Homo habilis is the oldest species given the designation Homo, by Leakey et al. in 1964.
The first eon in Earth's history, the Hadean, begins with the Earth's formation and is followed by the Archean eon at 3.8 Ga. [2]: 145 The oldest rocks found on Earth date to about 4.0 Ga, and the oldest detrital zircon crystals in rocks to about 4.4 Ga, [34] [35] [36] soon after the formation of the Earth's crust and the Earth itself.
2 billion High estimate until the Earth's oceans evaporate if the atmospheric pressure were to decrease via the nitrogen cycle. [98] 2.55 billion The Sun will have reached a maximum surface temperature of 5,820 K (5,550 °C; 10,020 °F). From then on, it will become gradually cooler while its luminosity will continue to increase. [86] 2.8 billion
A 12,000 year chronology places the end date at around 2400-2500 AD, which is why modern Zoroastrians believe they are living in the end few hundred years of the final era. [citation needed] Other dates for Zoroaster, however, differ and dates proposed for Zoroaster's birth range from 1750 to 500 BC.
The Solar System formed at about 9.2 billion years (4.6 Gya), [5]: 22.2.3 with the earliest evidence of life on Earth emerging by about 10 billion years (3.8 Gya). The thinning of matter over time reduces the ability of the matter to gravitationally decelerate the expansion of the universe; in contrast, dark energy is a constant factor tending ...