IN 4.5 billion yearsIt is sometimes abbreviated Gy, Ga ("giga-annum"), Byr and variants. The abbreviations Gya or bya are for "billion years ago", i.e. billion years before present. The terms are used in geology, paleontology, geophysics, astronomy, and physical cosmology.https://en.wikipedia.org › wiki › Billion_yearshistory, lifeThe history of life on Earth traces the processes by which living and fossil organisms evolved, from the earliest emergence of life to present day.https://en.wikipedia.org › wiki › History_of_life
The variety of life on Earth is widely considered to have evolved from a single common ancestor, but it is possible that basic organisms emerged more than once, leading to multiple trees of life.
The earliest life forms we know of were microscopic organisms (microbes) that left signals of their presence in rocks about 3.7 billion years old.
Life appeared 500 million years after the formation of earth, i.e., almost four billion years back approximately.
Life was already organising itself into large communities of cells more than a billion years ago, according to evidence from China. The centimetre-scale life forms were preserved in mudstones from the Yanshan area in the country's north and are dated to 1.56 billion years ago.
But Earth did not always exist within this expansive universe, and it was not always a hospitable haven for life. Billions of years ago, Earth, along with the rest of our solar system, was entirely unrecognizable, existing only as an enormous cloud of dust and gas.
Human evolution is the lengthy process of change by which people originated from apelike ancestors. Scientific evidence shows that the physical and behavioral traits shared by all people originated from apelike ancestors and evolved over a period of approximately six million years.
Although English naturalist Charles Darwin did not commit himself on the origin of life, others subscribed to hypothesis 4 more resolutely.
After things cooled down, simple organic molecules began to form under the blanket of hydrogen. Those molecules, some scientists think, eventually linked up to form RNA, a molecular player long credited as essential for life's dawn. In short, the stage for life's emergence was set almost as soon as our planet was born.
Adam is the name given in Genesis 1-5 to the first human. Beyond its use as the name of the first man, adam is also used in the Bible as a pronoun, individually as "a human" and in a collective sense as "mankind".
The First Humans
One of the earliest known humans is Homo habilis, or “handy man,” who lived about 2.4 million to 1.4 million years ago in Eastern and Southern Africa.
Scientists are exploring several possible locations for the origin of life, including tide pools and hot springs. However, recently some scientists have narrowed in on the hypothesis that life originated near a deep sea hydrothermal vent.
There have been five mass extinction events in Earth's history. In the worst one, 250 million years ago, 96 percent of marine species and 70 percent of land species died off. It took millions of years to recover.
Earth is the only planet known to maintain life. Find out the origins of our home planet and some of the key ingredients that help make this blue speck in space a unique global ecosystem.
Estimates range from 3 million to 100 million or even more.
While some evidence suggests that life may have originated from nonlife in hydrothermal vents on the ocean floor, it is possible that abiogenesis occurred elsewhere, such as deep below Earth's surface, where newly arisen protocells could have subsisted on methane or hydrogen, or even on ocean shores, where proteinoids ...
Divine creation, evolution, spontaneous generation, and cosmogenesis are the four theories examined.
Earth is estimated to be 4.54 billion years old, plus or minus about 50 million years. Scientists have scoured the Earth searching for the oldest rocks to radiometrically date.
No! After the dinosaurs died out, nearly 65 million years passed before people appeared on Earth. However, small mammals (including shrew-sized primates) were alive at the time of the dinosaurs.
From about 1.2 million years ago to less than 100,000 years ago, archaic humans, including archaic Homo sapiens, were dark-skinned.
Co-lead researcher Shimona Kealy said these people probably travelled through Indonesia's northern islands, into New Guinea and then Australia, which were part of a single continent between 50,000 and 70,000 years ago, when sea levels were 25-50 metres below the current level.
All life forms share at least one essential purpose: survival. This is even more important than another key purpose for life, reproduction. Plenty of organisms, after all, are alive but do not reproduce.
All of the planets, except for Earth, were named after Greek and Roman gods and godesses. The name Earth is an English/German name which simply means the ground. It comes from the Old English words 'eor(th)e' and 'ertha'. In German it is 'erde'.
Currently, the most favored explanation for where the Earth got its water is that it acquired it from water-rich objects (planetesimals) that made up a few percent of its building blocks. These water-rich planetesimals would have been either comets or asteroids.