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Life: Where Did It All Start?

Issue 48 of Cosmos, December 2012 by Robin McKie

Earth formed about 4.6 billion years ago and life first appeared here about a billion years later. Scientists don’t agree over the processes involved but, according to some theories, extremophiles were involved.

Charles Darwin suggested life began in "a warm little pond". Earth's early atmosphere would have been rich in methane, ammonia, and other gases on which lightning and radiation might have acted to create complex organics including amino acids. These would have rained down into pools on the surface. As concentrations grew, proteins and nucleic acids would have formed, eventually producing the first life-forms.

In deep-sea vents?

Some scientists believe life began near deep-sea hydrothermal vents. The energy liberated there would have fuelled the chemical reactions needed to construct complex proteins. This idea finds support in DNA sequences of modern organisms, which suggest the most recent common ancestor of all life was probably an aquatic micro-organism that lived in extremely high temperatures – a thermophile.

On Mars?

Life requires water but too much can be harmful. Some scientists think that drier Mars would have been the best bet as a birthplace for life. Meteorite impacts would have blasted Martian rocks into space and all the way to Earth, carrying life with them. The hardy ones would have colonised Earth. In short, we might all be Martians.

On unknown planetary systems?

Panspermia, the idea that life comes from space, was developed by Swedish scientist Svante Arrhenius who argued that bacterial spores from another planetary system, propelled through space by light pressure, seeded life here. British astronomers Fred Hoyle and Chandra Wickramasinghe later argued that comets could carry bacterial life across space and protect it from radiation damage en route.

A gift from aliens?

Scientists such as Francis Crick and the late Carl Sagan have suggested microbes might have been sent to Earth by an advanced civilization was facing catastrophic annihilation or hoping to adapt planets for later colonization. This concept is known as directed panspermia, and we are the end product.

http://www.cosmosmagazine.com/features/print/6377/life-where-did-it...

Tags: Darwin, Life, Mars, Sagan, aliens, beginning

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Comment by amer chohan on February 5, 2013 at 12:01pm: I like that Future, chosing not to go too far in the past is a good approach. Mankind had invented horrors like religion by habbit of looking too far back in the history of the universe.

Comment by Sidney M. Gonzalez on February 5, 2013 at 11:38am: "In trying to explain how life came to exist, people have been fixated on a problem of chemistry, that bringing life into being is like baking a cake that we have a set of ingredients and instructions to follow. That approach is failing to capture the essence of what life is about."
~ Paul Davies ~

Comment by Mark heartwell on January 31, 2013 at 4:40pm: High all..once apon a time,there was a WANT,a want to be..yes AWANTTOBE....and what does a want to be want to be...well it could not make up its mind because it didnt have one but wanted to be every thing and it said god help me I can't make up my mind because I don't have one I seem to be a big void of nothing which is totally snoreing boaring eh.
Then WAM BAM thank you MAM there was this violent but loving explosion that pulsated and climaxed out into the accepting womb of nothingness... and in essense it could be said the suns of creation was born ...only to be out done by their sisters who became mother earth....and so it was this heavenly marriage took place and a divine trine tied every thing all together as ONE TRUE LOVE and the life to experience it....some people say don't make a big something out of nothing..but clearly we have a lot of territory to cover with our star dust to find our image in the mirror of self realization..this my friends is how life evolved from the teeny we enie to the hue a Mung us we enie..it's just a matter of giving it up the ... let go let flow beyond boundaries ..now wasn't that oh so good ahh.. god I m tired.... snorezzzzzzzzz.

Comment by Future on January 31, 2013 at 10:44am: Mine started when mom and dad decided to have an extra glass of wine with dinner. Next thing you know, I was swimming my little tail off in the most important race of my life, emerging victorious over millions of other contestants.