Approximately how old is life on earth estimated to be

And how can we know with any degree of confidence? As Henry Reich describes in the video above , the process of scientifically estimating the age of the Earth revolves around, essentially, finding the oldest piece of the planet we can, then figuring out how old that piece is.

Finding super old rocks is conceptually straightforward, but practically difficult. The processes of plate tectonics mean that the Earth is constantly recycling its rock, breaking it down into magma in the interior before pumping it back up to the surface once more.

Samples in Western Australia run 3. Research groups in Australia found the oldest mineral grains on Earth. These tiny zirconium silicate crystals have ages that reach 4. Their source rocks have not yet been found. Meanwhile, scientists have also found 7-billion-year-old stardust on Earth.

The rocks and zircons set a lower limit on the age of Earth of 4. When life arose is still under debate, especially because some early fossils can appear as natural rock forms. Some of the earliest forms of life have been found in Western Australia, as announced in a study ; the researchers found tiny filaments in 3. Other studies suggest that life originated even earlier. Hematite tubes in volcanic rock in Quebec could have included microbes between 3.

Researchers looking at rocks in southwestern Greenland also saw cone-like structures that could have surrounded microbial colonies some 3. In an effort to further refine the age of Earth, scientists began to look outward.

The material that formed the solar system was a cloud of dust and gas that surrounded the young sun. Gravitational interactions coalesced this material into the planets and moons at about the same time. As advances in chemistry, geology, and physics continued, scientists found a method by which the absolute age—an actual number of years—of a rock or mineral sample could be determined.

This method is called radiometric dating , and it involves the decay, or breakdown, of radioactive elements. Using radiometric dating techniques, it became possible to determine the actual age of a sample. Radiometric dating requires an understanding of isotopes. Isotopes are variations of an element differentiated by the number of neutrons in their nuclei.

The isotopes of unstable radioactive elements—known as parent isotopes—eventually decay into other, more stable elements—known as daughter isotopes—in a predictable manner, and in a precise amount of time called a half-life. The half-life of an element is the amount of time required for exactly half of a quantity of that element to decay.

The age of a sample can be determined based on the ratio of parent to daughter isotopes within the sample.

One problem with this approach to dating rocks and minerals on Earth is the presence of the rock cycle. During the rock cycle, rocks are constantly changing between forms, going back and forth from igneous to metamorphic to sedimentary. This makes finding an exact age for Earth difficult, because the original rocks that formed on the planet at the earliest stages of its creation are no longer here.

The oldest rocks that have been found are about 3. To get around the difficulty presented by the rock cycle, scientists have looked elsewhere in the solar system for even older rock samples. They have examined rocks from the moon and from meteorites, neither of which have been altered by the rock cycle. The same techniques of radiometric dating have been used on those rocks.

All the data from Earth and beyond has led to the estimated age of 4. The age of rocks is determined by radiometric dating, which looks at the proportion of two different isotopes in a sample.

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Correspondence to Robert M. Portions of this article have been adapted from Hazen and Trefil and Trefil and Hazen Reprints and Permissions.

Hazen, R. Evo Edu Outreach 3, — Download citation. Published : 26 May Issue Date : June Anyone you share the following link with will be able to read this content:. Sorry, a shareable link is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing initiative.

Skip to main content. Search all BMC articles Search. Download PDF. Robert M. Abstract Earth scientists have devised many complementary and consistent techniques to estimate the ages of geologic events. Annual Rock Clocks Rocks reveal their ages of formation in several ways and provide Earth scientists with their most reliable clocks. Full size image. However, the volcano rises approximately 10, meters above the ocean floor, so a rough calculation gives its age: Fig.

Radiometric Dating The physical process of radioactive decay has provided Earth scientists, anthropologists, and evolutionary biologists with their most important method for determining the absolute age of rocks and other materials Dalrymple ; Dickin Table 1 Common radioactive elements and their half-lives Full size table. Created Antiquity Overwhelming observational evidence confirms that Earth history is the story of the co-evolving geospheres and biospheres: Life has changed continuously over the course of Earth history.

Conclusions Many lines of evidence point to the unfathomable antiquity of Earth. References Dalrymple GB. Google Scholar Dickin AP. Book Google Scholar Fowler B. Google Scholar Download references. Hazen Authors Robert M. Hazen View author publications. Additional information Portions of this article have been adapted from Hazen and Trefil and Trefil and Hazen About this article Cite this article Hazen, R.

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