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The first known mass extinction was the Great Oxidation Event 2.4 billion years ago, which killed most of the planet's obligate anaerobes. Researchers have identified five other major extinction events in Earth's history, with estimated losses below: [11] End Ordovician: 440 million years ago, 86% of all species lost, including graptolites
Development before birth, or prenatal development (from Latin natalis 'relating to birth') is the process in which a zygote, and later an embryo, and then a fetus develops during gestation. Prenatal development starts with fertilization and the formation of the zygote , the first stage in embryonic development which continues in fetal ...
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 benefits of walking abound—improving heart health, sleep quality, and mood are just a few of the many pros of going for a stroll. Now, new research has found that walking could add over 10 ...
The timeline of human evolution outlines the major events in the evolutionary lineage of the modern human species, Homo sapiens, throughout the history of life, beginning some 4 billion years ago down to recent evolution within H. sapiens during and since the Last Glacial Period.
Cave paintings (such as this one from France) represent a benchmark in the evolutionary history of human cognition. Victorian naturalist Charles Darwin was the first to propose the out-of-Africa hypothesis for the peopling of the world, [40] but the story of prehistoric human migration is now understood to be much more complex thanks to twenty-first-century advances in genomic sequencing.
The finding that "Mitochondrial Eve" was relatively recent and African seemed to give the upper hand to the proponents of the Out of Africa hypothesis.But in 2002, Alan Templeton published a genetic analysis involving other loci in the genome as well, and this showed that some variants that are present in modern populations existed already in Asia hundreds of thousands of years ago. [31]
Human history is the record of humankind from prehistory to the present. Modern humans evolved in Africa around 300,000 years ago and initially lived as hunter-gatherers.They migrated out of Africa during the Last Ice Age and had spread across Earth's continental land except Antarctica by the end of the Ice Age 12,000 years ago.