posted on Oct, 23 2013 @ 09:51 AM
reply to post by Agree2Disagree
What I should have said is why does evolution "work" as a survival tool for some organisms while it seemingly "failed" as a survival
mechanism for many other organisms....
I see you've already been talking about this with Phage. I don't know if I can make things clearer than he has, but I'll try.
The first thing you have to understand is that organisms
don't adapt. Species
Evolutionary events, as Phage explained, are caused by a change in the environment that affects different members of a species in the same way, but to
different degrees. When a change like this comes along, the individuals who will survive it and thrive on it are already adapted
. The rest, who
can't cope with the change and will be weeded out, lack the adaptation. Earlier, the ones who lacked the adaptation may have been in the majority.
Afterwards, they will be in a minority, or may have died out altogether. The species as a whole has adapted to the new environment. It has evolved.
An example will make it clear. Imagine a species of grazing animal that evolved under cloudy skies. Since solar radiation is not excessive in their
habitat, they are mostly light-skinned, although some are darker than others and a few are very dark. The population thrives and its range begins to
widen. Some groups travel southwards, to where the skies are clearer. The grazing is good there, the predators are not (yet) interested in them, and
everything would be great if only they didn't die like flies from skin cancer.
But a few grazers, the darker-skinned ones, are more resistant to the solar radiation than their paler brethren. They will survive and reproduce while
the pale ones die out. In a few generations, the southern grazers are nearly all dark-skinned (there are a few albinos, which fail to thrive and
rarely reproduce). What has happened? The population has adapted and evolved. But no individual member of the population started out pale-skinned and
picked up a serious tan. No individual
I hope that was of use.