Tuesday, August 30, 2005

Origins of life on Earth are proving elusive

Geologists recently have learned more about the conditions on our planet that could have made life possible as long as 4 billion years ago. And thanks to the DNA revolution, biologists now can trace the development of modern organisms — ranging from simpler forms such as mushrooms and flowers to more complicated ones such as humans — back to primitive microbes that lived in the ocean more than 2.7 billion years ago. At some point in between, lifeless molecules — combinations of atoms — learned to eat, breathe, move and reproduce. No one's certain when and how they did it, however. As early as 150 million years after the Earth formed, 4.5 billion years ago, the planet had cooled enough to have an atmosphere, an ocean and some dry land. Chemical reactions between hot water and rocks produced more and more complex molecules. Later, probably sometime between 4 billion and 3.8 billion years ago, these inorganic molecules grew and clotted together in "protocells." They formed organic compounds necessary for life. At some point in this process came the crucial, still-unexplained step: the advance from clumps of molecules to living cells containing an early version of DNA known as RNA. DNA contains the instructions to make proteins, the building blocks of every living thing. "I believe life began very early, before 4 billion years ago". However, the evidence for such a quick start was limited to "squiggles in the rocks" in Greenland and Australia that might represent ancient fossils. The oldest positive evidence for living microbes is dated at 2.7 billion years ago.

5 Comments:

At August 30, 2005 3:57 AM, Blogger Seahawk said...

"As early as 150 million years after the Earth formed, 4.5 billion years ago, the planet had cooled enough to have an atmosphere, an ocean and some dry land.'

But you need a lot more than that for life.
You need a planet with a liquid iron core, to provide a magnetic field shield. You need to be at the right distance from the sun (not too far, not too close). You need large planets to serve as "blockers" to catch incoming debris from space. You need a huge moon to keep the seas moving so they don't become stagnant. You need to be at the right distance from the core of the galaxy (not too close, or too far--the radiation at the center would kill any chance of life, for instance).
In short, there are about 20 factors necessary for life as we know it to be even possible.
And to produce a DNA chain that would contain as many complications as the human DNA, would be simply impossible by random chance. The odds are simply not even calcuable.
(Sorry if that ruins anyone's day. . . )

 
At August 30, 2005 12:37 PM, Blogger sissyblue said...

Seahawk, Interestingly it was just such arguments (particularly the complexity od DNA) that changed Anthony Flew's mind (famous aetheist philosopher of our time):
http://www.philosophynews.com/common/textharness.aspx?pid=flew_theist

 
At August 30, 2005 2:04 PM, Blogger Bom Garfo said...

Not a chance ;)

 
At August 30, 2005 4:37 PM, Blogger Bellicose Woman said...

Quite a bit of a chance, actually. Scroll down to the section on Dean Overman

 
At August 30, 2005 6:04 PM, Blogger sissyblue said...

What I don't understand is that as long as we've been tracking these things, we've never seen anything "evolve" for the better. We see viruses and bacteria evolving to our detriment all the time. You'd think we would see at least one example of a virus evolving which would make, for instance, muslims less violent and intolerant! Or how about a virus that feeds on cancer cells? It just seems all this "evolution" is trying to kill us and not make things better.

Fjordman, I like the new security! You're too clever:>)

 

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