Evolving Senses

[Lestat]

Warning: This post has idiot rambling and some very dumb questions. Feel free to flame my stupidity, but please have the class to at least provide me with some insight.

I often wonder how we evolved to have the senses that we have. To me, it's quite remarkable that we have eyes to see the world, and ears to hear sounds. I suppose I can imagine how we developed the sense of taste. It makes sense that when an organism ingests something which can kill or harm it, it would evolve a distate for it. Likewise, when something is healthy, we would devolop a pleasing sense (although I'm not sure how this explains why in today's world almost everything that tastes good to me, is unhealthy -lol). In addition, I understand how other poisenous living things evolved to taste bad so that others wouldn't eat it. So ok, to a childlike degree I guess I understand a little (but it's probably still very wrong).

But the eye... That has to be one of the most amazing evolutionary inventions. What evolutionary pressure could've been put on an organism that would a). Allow an organism's genes to realize that visual sight was even possible, and b). To then select for it?

Aren't plants and trees among the only organisms that don't have sight? All other organisms that do not employ sight live in places where visual sight is impossible (or not very practical, such as the bottom of the see, or underground, or those that dwell in the darkness of night).

So what was it about light that tipped off a gene that sight was even possible, let alone beneficial?

Again, I'm willingly showing my ignorance and incompetence to gain even a little insight to better understanding this. Thanks.