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[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] However, a 2016 report estimates an additional 1 trillion microbial species, with only 0.001% described. [6]
Evidence of bacteria has been discovered in the Australian Apex Chert near ancient hydrothermal vents. [12] [13] These rocks date back 3.46 billion years and, because oxygen was not present in large quantities in Earth's early atmosphere, these fossils are thought to represent early thermophilic bacteria, which do not require oxygen to survive ...
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 discovery of microorganisms such as Euglena that did not fit into either the animal or plant kingdoms, since they were photosynthetic like plants, but motile like animals, led to the naming of a third kingdom in the 1860s. In 1860 John Hogg called this the Protoctista, and in 1866 Ernst Haeckel named it the Protista. [20] [21] [22]
The Boring Billion, otherwise known as the Mid Proterozoic and Earth's Middle Ages, is an informal geological time period between 1.8 and 0.8 billion years ago during the middle Proterozoic eon spanning from the Statherian to the Tonian periods, characterized by more or less tectonic stability, climatic stasis and slow biological evolution.
Starting in 1985, researchers proposed that life arose at hydrothermal vents, [234] [235] that spontaneous chemistry in the Earth's crust driven by rock–water interactions at disequilibrium thermodynamically underpinned life's origin [236] [237] and that the founding lineages of the archaea and bacteria were H 2-dependent autotrophs that used ...
Some bacteria transfer genetic material between cells. This can occur in three main ways. First, bacteria can take up exogenous DNA from their environment in a process called transformation. [138] Many bacteria can naturally take up DNA from the environment, while others must be chemically altered in order to induce them to take up DNA. [139]
Earth forms 3.4 billion years ago First photosynthetic bacteria appear 2.7 billion years ago Cyanobacteria become the first oxygen producers 2.4 – 2.3 billion years ago Earliest evidence (from rocks) that oxygen was in the atmosphere 1.2 billion years ago Red and brown algae become structurally more complex than bacteria 0.75 billion years ago