How did evolution begin?

Question

Life on earth that is and evolution of life. What are the most common theories about the origin of life?

bucknasty - how did the cells form?

koldsauce12 - but how did the first life force form?

Answer 1

Evolution began because the mechanisms for it are built into living organisms. What those living organisms were is still up for debate, but where they came from is being hypothsized. Here are some:

+Panspermia, which says life came from someplace other than earth. This theory, however, still does not answer how the first life arose.

+Proteinoid microspheres (Fox 1960, 1984; Fox and Dose 1977; Fox et al. 1995; Pappelis and Fox 1995): This theory gives a plausible account of how some replicating structures, which might well be called alive, could have arisen. Its main difficulty is explaining how modern cells arose from the microspheres.

+Clay crystals (Cairn-Smith 1985): This says that the first replicators were crystals in clay. Though they do not have a metabolism or respond to the environment, these crystals carry information and reproduce. Again, there is no known mechanism for moving from clay to DNA.

+Emerging hypercycles: This proposes a gradual origin of the first life, roughly in the following stages: (1) a primordial soup of simple organic compounds. This seems to be almost inevitable; (2) nucleoproteins, somewhat like modern tRNA (de Duve 1995a) or peptide nucleic acid (Nelson et al. 2000), and semicatalytic; (3) hypercycles, or pockets of primitive biochemical pathways that include some approximate self-replication; (4) cellular hypercycles, in which more complex hypercycles are enclosed in a primitive membrane; (5) first simple cell. Complexity theory suggests that the self-organization is not improbable. This view of abiogenesis is the current front-runner.

+The iron-sulfur world (Russell and Hall 1997; Wächtershäuser 2000): It has been found that all the steps for the conversion of carbon monoxide into peptides can occur at high temperature and pressure, catalyzed by iron and nickel sulfides. Such conditions exist around submarine hydrothermal vents. Iron sulfide precipitates could have served as precursors of cell walls as well as catalysts (Martin and Russell 2003). A peptide cycle, from peptides to amino acids and back, is a prerequisite to metabolism, and such a cycle could have arisen in the iron-sulfur world (Huber et al. 2003).

+Polymerization on sheltered organophilic surfaces (Smith et al. 1999): The first self-replicating molecules may have formed within tiny indentations of silica-rich surfaces so that the surrounding rock was its first cell wall.

(all sources can be referenced here: http://talkorigins.org/indexcc/CB/CB010_2.html)

Answer 2

Panspermia is a theory from Fred Hoyle and Chandra Wickramasinghe stating that the seeds of life are everywhere, and that life on Earth came from space.

Chemosynthetic theory, the concept of the primordial soup. Earth was a very volcanic place until chemical synthesis occured to make the environment suitable for living things, but it starts with the single celled organisms up to the complex.

Answer 3

In a sence, evolution had no beginning because the universe itself has evolved out of a featureless mass of matter and energy when the "big bang" happened. It appears evolution is a natural phenomenon.

Reguarding life on earth, it is theorized that organic compounds became very complex on the early earth because there was neither life nor oxygen. Either of the two would have destroyed these compounds. Left free to recombine as they may, the ones able to replicate themselves survived, those which did not went extinct. This was not actually life, just a bunch of chemistry going on.

A good anology is "mad cow disease". This is caused by an abnormal brain protien able to modify a similar protien and in doing so, make a copy of itself. Again, this protien is just a chemical; however, it behaves as though it were alive because it can replicate itself. It is able to do this because it has nothing in its environment which could destroy it.

Answer 4

The most common theory claims that macromolecules started forming into organized units. These units became cells. It makes sense if you look at RNA. Many think that RNA was actually the start to cells. RNA is unique because not only does it store genetic information, but it also has enzyme properties.

Answer 5

Well, according to natural selection, ever since the first living things came about, there were differences in their genetics, so obviously some had better genetics to survive in the environment, the ones whose genetics were bad for the environment died off, and only the good genetics came about.

That kept happening until the species was totally different etc etc

Answer 6

Evolution began when there was a mutation in the cell of a unicellular organism. Then that organism began to reproduce and more mutations occured.

Answer 7

Evolution begins whenever there's something that can adapt and some environmental condition that it can adapt to better exploit or survive.
Actually, I'm with Creolegirl on this one, too - personally I don't believe we came from our "parents", because they're still here! I think that we were all individually created by God playing Sims.

Answer 8

Time unknown all species existed simultaneously. Just because human beings decomposed the matter to cells, electron, proton, neutron, photon, etc. doesn’t mean the reverse is true.

Answer 9

Evolution started when Darwin wanted to marry his first cousin.
His parents sent him on a cruise to get his mind off of her.
Darwin was really mad at God, for forbidding his love.
The Devil gave Darwin the idea of evolution. Darwin thought, this is great. Now I can marry my cousin and we will have superior children. So he did. They did have a bunch of children.
Most of which were handicapped.
That's the story I heard!

Answer 10

either God created the first cells which is unscientific.
or acids formed in the oceans and assembled which is virtually impossible.