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The tree of life on Earth

The border between living and inanimate

 Automatic translation  Automatic translation Updated June 01, 2013

Life is a chemical process in which living organisms are derived. The material life is present on Earth and probably elsewhere in the universe for billions of years.
Organics in meteorites, the oldest material, scientists can find the basics of life that have supported primitive soup on Earth, there are 4 billion years. Life began in protecting within cell membranes, life on Earth is cellular. A mixture of organic compounds as simple as that contained in a carbonaceous meteorite can form cell membranes and this has contributed to the formation of the first cells on the primitive Earth.
Scientists perceive the early stages of creating the first living cells, but very old organic molecules and cell membranes can reveal almost nothing of the mysterious passage of matter to life.
What is certain is that we are made of matter but at the same time, we distinguish. What sets us apart from the matter is that we are alive, not inert.
It is said that a body is alive if it can feed, grow and reproduce in order to cross the time.
Since the chemical and life stems from the inert matter,


why does there not specify the boundary between the living and the inanimate?
A virus for example, is a collection of inert atoms, it is inanimate, and yet he acts like a living organism and breeding mutant, when infecting a cell. The dead and the living is strangely in the crystal that grows and multiplies while being inert.
The arches are cells 10 times smaller than bacteria and their DNA sequence, shows that they are closer to the first living organism than bacteria. Can be found on Earth who live in extreme conditions, which shows their phenomenal capacity to adapt.
That's why researchers are trying to remove the maximum amount of information stored in their DNA to keep only a living organism "minimum" and thus reach the border between inanimate and living.

Image: Methanogenic microorganisms are in the branch of Archaea and producing methane. This gas has played a major role in evolution.


The reign of the living


Fungi, animals, plants are grouped on the same branch of the tree of life, the branch cell or eukaryotic nuclei.
Bacteria represent life in its most simple and yet it can grow and multiply at very high speed. Bacteria form the second part of the tree, cells with no nucleus or Eubacteria. The Archaea or arches or archaea represent another distinct branch of the tree. Scientists classify the living world into three parts, however, the genetic code that can be found everywhere on Earth is unique.
There is therefore only one form of life on Earth and we have no other example of life based on chemistry or another on a different genetic code. Are we alone in the Universe is a huge issue, but today it is unthinkable to believe that life exists on Earth, wherever there is liquid water, there is a possibility of life even in the icy crust of certain planets and satellites of planets. Life grows in places where even the sun's energy does not penetrate, we see on our planet. The oldest fossil bacteria are very old, they date back 3.5 billion years, the oldest traces of terrestrial life. The oldest terrestrial rocks dating from 3.9 billion years and the information they contain show signs of life. If the signature of life is present in rocks older is that life appeared very early with this complexity. One could easily believe it emerges on the planet because life is intimately linked to the planets.
Life on Earth has moved in one direction over the environmental trends, constraints and genetic mutations accident, leaving some cash on the way to encourage others. Species well adapted to their environment continue their path and reproduce.


The evolutionary tree shows the extreme diversity of life which was organized from the cellular industry and yet the 3 to 30 million estimated species currently represent only 1% of all species lived on Earth.
Bacteria specialize and evolve with a very high speed to adjust and life could start again, from these simple cells. Contingency prevent the tree of life to evolve in the same way and he never found the same evolutionary path if everything had to start over from scratch. To understand life, we must find another way of life to which we compare because we are prisoners of our tree of life and we can not collect more. This prevents us to imagine another form of life on a planet other than Earth. Our Milky Way contains 100 billion stars, in addition, billions of galaxies also contain 100 billion stars and all these stars can have around them planets carrying life in another form likely.
There must be an infinity of worlds in the universe and those other worlds are probably inhabited by life, but how to recognize it?
The universe is full of life and something connects us to the matter, a cosmic link that we can not imagine for the moment.

Image: Tree of Life by American microbiologist Carl Richard Woese who defined in 1977, the Arches, one of three areas of living or reign.

 Tree of life, bacteria, archaea, eukaryotes

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