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.
Once the early rain of comets and asteroids upon the Earth subsided somewhat, subsequent impacts may well have delivered the water and carbon-based molecules to the Earth's surface - thus providing the building blocks of life itself.
When did life on Earth begin? Earth is about 4.5 billion years old. Scientists think that by 4.3 billion years ago, Earth may have developed conditions suitable to support life. The oldest known fossils, however, are only 3.7 billion years old.
In Earth's Beginning
At first, it was extremely hot, to the point that the planet likely consisted almost entirely of molten magma. Over the course of a few hundred million years, the planet began to cool and oceans of liquid water formed.
The earliest time of the Earth is called the Hadean and refers to a period of time for which we have no rock record, and the Archean followed, which corresponds to the ages of the oldest known rocks on earth. These, with the Proterozoic Eon are called the Precambrian Eon.
Homo sapiens, the first modern humans, evolved from their early hominid predecessors between 200,000 and 300,000 years ago. They developed a capacity for language about 50,000 years ago. The first modern humans began moving outside of Africa starting about 70,000-100,000 years ago.
Scientists still don't know exactly when or how the first humans evolved, but they've identified a few of the oldest ones. 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.
The name Earth derives from the eighth century Anglo-Saxon word erda, which means ground or soil, and ultimately descends from Proto-Indo European *erþō. From this it has cognates throughout the Germanic languages, including with Jörð, the name of the giantess of Norse myth.
Washington, DC—Our planet's water could have originated from interactions between the hydrogen-rich atmospheres and magma oceans of the planetary embryos that comprised Earth's formative years, according to new work from Carnegie Science's Anat Shahar and UCLA's Edward Young and Hilke Schlichting.
Before Earth and the Moon, there were proto-Earth and Theia (a roughly Mars-sized planet). The giant-impact model suggests that at some point in Earth's very early history, these two bodies collided.
Modern humans originated in Africa within the past 200,000 years and evolved from their most likely recent common ancestor, Homo erectus, which means 'upright man' in Latin. Homo erectus is an extinct species of human that lived between 1.9 million and 135,000 years ago.
Most scientists agree the Earth formed just 4.5 billion years ago. Assuming that Moore's Law does apply to biological complexity, this would suggest that life began somewhere other than on Earth and migrated here.
Our species, Homo sapiens, has now spread to all parts of the world but it's generally believed that we originated in Africa by about 200,000 years ago. We interacted with local archaic human populations as we colonised the globe.
Exactly how DNA came into existence is still a mystery. Conventional wisdom suggests that RNA-based life eventually switched to DNA to take advantage of its stability, which makes it better at storing genetic information. But so far, there is little evidence about how this could have happened.
Our universe began with an explosion of space itself - the Big Bang. Starting from extremely high density and temperature, space expanded, the universe cooled, and the simplest elements formed. Gravity gradually drew matter together to form the first stars and the first galaxies.
The oldest hominins are thought to have appeared as early as 7 million B.C.E. The earliest species of the Homo genus appeared around 2 million to 1.5 million B.C.E. Current evidence supports modern Homo sapiens appearing around 190,000 B.C.E.
Related Story. "This means that water in our solar system was formed long before the sun, planets, and comets formed," Merel van 't 'Hoff, a University of Michigan astronomer and co-author of the paper, says in the news release.
Not all water in the Solar System today could have formed here, researchers say. As much as half of the water in Earth's oceans could be older than the Sun, a study has found.
The center of the earth lies 6,400 kilometers (4,000 miles) beneath our feet, but the deepest that it has ever been possible to drill to make direct measurements of temperature (or other physical quantities) is just about 10 kilometers (six miles). Sign up for Scientific American's free newsletters.
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'.
Earth is the only planet in our solar system not named after a Greco-Roman deity. The name used in Western academia during the Renaissance was Tellus Mater or Terra Mater, the Latin for “earth mother”, i.e. “Mother Earth”, goddess of the earth in ancient Roman religion and mythology.
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".
Genetics Suggest Modern Female Came First.
On November 24, 1974, fossils of one of the oldest known human ancestors, an Australopithecus afarensis specimen nicknamed “Lucy,” were discovered in Hadar, Ethiopia.