@Zetherin,
Zetherin;140351 wrote:I thought natural selection was a process of evolution. I did not know there was natural selection without evolution. Do you have any sources where I could learn about such a thing?
I do find this a tricky one myself. Evolution as colloquially understood can just mean change over time - the evolution of aeroplane design, or evolution of religion.
However, the theory of evolution applies to the diversity of living things.
Natural selection is a component of this (a very big one) but not the only, as genetic drift isn't natural selection as we think of it (being down to luck rather than selective pressures).
There is also stuff like sexual selection or breeding organisms that have a symbiotic relationship with other organisms - though I would tend to think of these as natural selections, even in the case of breeds of dog, because the decisions of another organism are natural pressures - though others would argue that and I'm not so attached to the idea that I would spend much time defending it personally.
Quote:And you are saying that scientists use natural selection to explain the origins of life? That is the 'first cause'? I don't think they do. But, again, any sources are welcomed.
The problem here, I think, is the scientific definition of life.
Most models of abiogenesis run along the following lines.
1) organic compounds form - as they do naturally in many environments, including deep space afaict.
2) under the right conditions the compounds form polymers (such as amino acids).
3) the polymers split and self replicate (such as RNA and the more complex DNA).
4) the self-replicating polymers form symbiotic relationships with phospholipid bilayers (at this stage we see something like a primitive cell).
5) the polymers not only self replicate, but cause other polymers to bond to them and form proteins (these perform tasks in the protocell like strengthening the wall, allowing certain chemicals in or out, helping the self-replication process).
6) the proteins function to such a degree that the primitive cell has what we would call a metabolism.
Now life happens at 6 (otherwise you get some odd examples of things being called life that aren't really life - like crystals for example - scientists tend to agree on a definition of life that requires 'metabolising stuff') - but natural selection would be occuring as early as 3 (because certain types of self-replicating polymers will do better than others and therefore become more prevalent in that niche).
Lots of sources exist - and some of them agree and some of them don't and some sort of do - because this is a field of research in it's infancy. So I do admit to a little subjective bias in my terminology. I do like the vids I posted earlier on this thread which go into more detail.
In summary I would say evolution as in "the theory of" starts at life, but life starts at metabolism. If abiogenetic ideas turn out to be demonstrable natural selection happens earlier than life.
