Prepare a verbal presentation on the topic “EVOLUTION OF THE LIFE STYLE IN THE INTERNAL ERA.”
Answers
Answer:
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. 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] (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.[1][4][5][6]) The similarities among all known present-day species indicate that they have diverged through the process of evolution from a common ancestor.[7] Approximately 1 trillion species currently live on Earth[8] of which only 1.75–1.8 million have been named[9][10] and 1.8 million documented in a central database.[11] These currently living species represent less than one percent of all species that have ever lived on Earth.[12][13]
Life timeline
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−4500 —–−4000 —–−3500 —–−3000 —–−2500 —–−2000 —–−1500 —–−1000 —–−500 —–0 —
Water
Single-celled
life
Photosynthesis
Eukaryotes
Multicellular
life
Arthropods Molluscs
Plants
Dinosaurs
Mammals
Flowers
Birds
Primates
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Earliest Earth (−4540)
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Earliest water
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Earliest life
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LHB meteorites
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Earliest oxygen
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Atmospheric oxygen
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Oxygen crisis
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Earliest fungi
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Sexual reproduction
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Earliest plants
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Earliest animals
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Ediacaran biota
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Cambrian explosion
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Tetrapoda
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Earliest apes
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A
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Pongola
Huronian
Cryogenian
Andean
Karoo
Quaternary
Ice Ages
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Earliest multicell life
(million years ago)
The earliest evidence of life comes from biogenic carbon signatures[2][3] and stromatolite fossils[14] discovered in 3.7 billion-year-old metasedimentary rocks from western Greenland. In 2015, possible "remains of biotic life" were found in 4.1 billion-year-old rocks in Western Australia.[15][5] In March 2017, putative evidence of possibly the oldest forms of life on Earth was reported in the form of fossilized microorganisms discovered in hydrothermal vent precipitates in the Nuvvuagittuq Belt of Quebec, Canada, that may have lived as early as 4.28 billion years ago, not long after the oceans formed 4.4 billion years ago, and not long after the formation of the Earth 4.54 billion years ago.[16][17]
Microbal mats of coexisting bacteria and archaea were the dominant form of life in the early Archean Epoch and many of the major steps in early evolution are thought to have taken place in this environment.[18] The evolution of photosynthesis, around 3.5 Ga, eventually led to a buildup of its waste product, oxygen, in the atmosphere, leading to the great oxygenation event, beginning around 2.4 Ga.[19] The earliest evidence of eukaryotes (complex cells with organelles) dates from 1.85 Ga,[20][21] and while they may have been present earlier, their diversification accelerated when they started using oxygen in their metabolism. Later, around 1.7 Ga, multicellular organisms began to appear, with differentiated cells performing specialised functions.[22] Sexual reproduction, which involves the fusion of male and female reproductive cells (gametes) to create a zygote in a process called fertilization is, in contrast to asexual reproduction, the primary method of reproduction for the vast majority of macroscopic organisms, including almost all eukaryotes (which includes animals and plants).[23] However the origin and evolution of sexual reproduction remain a puzzle for biologists though it did evolve from a common ancestor that was a single celled eukaryotic species.[24] Bilateria, animals having a left and a right side that are mirror images of each other, appeared by 555 Ma (million years ago)