If it can go back and forth, then why would it always seem to move forwards to a 'destination'? How can random set a goal?
Because of selection. The environment (the sun, the air pressure, other animals) selects for certain combinations of features. Imagine if you had a jar full of jellybeans, but you didn't like the brown ones, and didn't eat them. After some time, all the beans in the jar would be brown.
Let me use this one as an example: it's easy to say a horse developed enamel and extra toes at the same time, right? But why do we never see a creature (now or in the fossil record) with extraneous parts? Where is the creature with half of an echolocation system in place? I know the easy way out is to say there are creatures with flipper-feet; but that itself serves a specific purpose - a creature simply spends a lot of time in water and a lot out, like a seal. That is not a half evolved creature, its parts serve a very specific purpose, and not to gradually become aquatic or to 'crawl from the sea'.
Why would evolution ever select for an extraneous body part, though?
Think of it like this- if the whales went extinct tomorrow, who would be at a better advantage to take their place as huge, marine mammals, seals and otters, with in between organs, or animals without any flippers?
Gross anatomical features are huge investments of resources, so shouldn't be expected to pop up willy-nilly overnight. They will most likely appear in stages, getting bigger or small, much like with the horse examples, or from dinosaur to bird. Those horse fossils are an awesome example of change over time.
Maybe the few critters that we can imagine up a real good reason and sequence for evolution just look that way - you know, like a coincidence. There seems to be no good reason for most animals to evolve.
Evolution is defined as a change in allele frequency over time. So as long as selection continues to weed out mutants, evolution does not occur. However, given small enough population sizes or big enough environmental chnages (meteor impacts, volcanic eruption), you get changes in allele frequency independent of selection. Accidents are a huge driving force behind evolution.
Given our very narrow time frame, most animals shouldn't have a whole lot of reason, or time, to evolve. But given the mass extinction event happening, we can expect animals to move into niches that they previously couldn't compete for, and change to fill it.
Plus there is a huge balance in nature. One creature cannot evolve simultaneously with several others, each to benefit each other.
Why not? Mutualisms exist all over the place. The bacteria in your stomach right now, for instance. Or the mitochondria in your cells.
How could a creature mutate and keep the mutation when it only helps something else? That seems counter-intuitive to the evolutionary process.
Many mutualisms are hypothesized to have started as either a commensalism or parastism. Some are simply luck. The hyperaggressive
Pseudomyrmex, a genus of ant that lives in bullhorn acacias, defends the plant, and the plant gives it a place to live. One could imagine that the ant merely lived on the plant and ate bugs there. The plant gained a slight benefit from the ant picking off bugs, and the ants had a place to live. A mutation in the plant maybe led it produce some food for the ants, or a better place to live, so the ants did better and killed more bugs. Over time, they developed to be almost completely dependent on each other.
Honestly, I would say to this comment that you didn't look very hard. But then I have no idea what you are basing this conclusion on. Seems like a blanket statement based in frustration, anger, or both - at people in a church or the church in general; likely stemming from a severe lack of understanding - possibly on both sides.
I think you missed the point.