Why would life have moved from the comfy waters to the harsher environment of land?
If you`re going to evolve why would you make things harder for yourself?
The ocean has a relatively stable temperature, protection from the elements, endless food sources and vast expanses for which to roam. I cant imagine what land had to offer to the evolving species that the ocean didnt already provide.
Niches with no competition (yet), for one thing.
Escape from predation.
But it sounds like you’re imagining that the move onto land was some kind of conscious decision on the part of the organisms involved.
It was evolution. Some species went from the oceans to the land, then back to the ocean. And it’s not as nice and cozy as you are making it out to be. And who says we are not moving back to that idea anyway with underwater cities, generators, floating cities… Who knows that the future holds?
I thought another factor was survival from weather/water level changes. Didn’t the earliest lungfish develop the ability to process oxygen out of air in addition to water in part to survive long dry seasons?
The fact that they emerged from a dry spot and found that some plant life had also adapted to land that they could eat gave them the opportunity, if you will, to experience less predation and the ability to procreate.
That fact that it happened is evidence that your premise is wrong.
Apprently, some life forms benefitted by having things that were suitable to land (oversimplification), and that enabled them to have more members reach reproductive age and have more succesful reproductions. Maybe it all started with egg laying out of water.
I always hated the way evolution was explained. Actually nothing evolves for a purpose or in response to adapt. What is the purpose of claws? They have no purpose, but they have a consequence. What is the purpose of a creature that can absorb oxygen out of air rather than water? There is no purpose, but their is a consequence. Those ‘adaptations’ that have a positive consequence on the reproductive rates get passed on.
So, since we have the advantage of hindsight, we can say that changes that allowed movement toward land life had some positive consequences.
Vertebrates: ever get a close look at a shark?
Invertebrates: Filter feeders are scaaaaary…
Unexploited real estate, cheap
The first organisms onto the land were plants, probably lichens or liverworts or similar, in the splash zones near the sea, clinging to rocks and basking in the much greater available light energy out of the water.
Plant eating animals of some kind (probably isopods or similar)followed, then predators (probably eurypterids or similar) to eat the plant eaters.
But it all happened by chance, evolution has no goal in mind. Evolution in fact has no mind.
SF worldbuilding at
http://www.orionsarm.com/main.html
I wouldn`t say that. The theory that life started in the waters to begin with probably means that the waters were more suitable for life at the time.
Mangetout - wouldn`t avoiding a predator be a concious decision?
not necessarily. A gene that codes for an “unconcious” preference for land would be just as good. E.g worms hide in tunnels partially to get away from birds, but that is not a concious decision
Again, this presupposes conscious intent or purpose as opposed to simple consequence. Merely escaping predation by accident will still serve to increase your odds of survival.
Someone has hinted at the most likely scenario but not specifically mentioned it. The theory is that land life evolved in tidal pools and splash zones. These marginal areas were colonized as “extensions” of the oceans. Their relative dryness then drove evolution towards land survivability.
But the way evolution works, moving to dry land doesn’t have to provide any benefits to the organism, compared to staying in the ocean. It could be way worse and harder and all that, but if the first mutants to move out of the ocean reproduce more often than they die, then they’ll become more common. Sounds kinda true by definition, but that’s pretty much it. They don’t have to be ``better’’ in any way shape or form. Only when resources become limiting does being better than the next guy matter, because then you get the resources and the next guy doesn’t, so you reproduce while he dies. But whether or not there’s a next guy there or not, the crucial comparison is not whether you are better or worse than he, but whether you and your kind reproduce more often than you die. If you do, your kind increases. If you don’t, your kind decreases.
It’s so frikkin’ true by definition, it is amazing people don’t believe in evolution 
That only means that the ocean was the best place for life to begin; after hundreds of millions years of evolution, don’t you think it is likely that various life forms might find a different habitat advantageous?
Dogface, Viking - good points. Im beginning to think it was more of an accident than anything. Sort of like when someone says the average houseflies life expectancy is three days, yet you always seem to find the one in the windowsill that survived the entire winter. Can`t really be explained with any lack of ambivalence.
All of the above. My picture is that first some plants developed the ability to survive short periods of dryness. This gave them the advantage to move into the unexploited tidal pools which was an advantage because there was no competition and nothing munching them. BTW, the moon was much closer and the tides would have been gigantic (tidal forces are inversely proportional to the cube of the distance so a moon at 1/10 the distance–as it originally was–would have led to tides 1000 times as large!). Later, animals that could stand some drying found a whole unexploited niche of munchables and followed them. Then some plants, followed by some animals evolved to stand dryer and dryer conditions until species evolved that could leave the ocean behind (of course, they needed some source of water) and found entire continents to exploit.
To boldly go where no plant has gone before…
Species evolve; individual organisms die. A species doesn’t have a strategy, or intent, or even an awareness of the possibility. Its individual members just manage to reproduce before they die. They don’t decide to go to another environment, they suffer a change of environment, and most of them die.
So, spoors deposited on land in tidal zones died in the trillions. But the unusual few survived. Rinse and repeat. Wait a billion years, and you have plants on the land. The animal thing is pretty much the same. Critters get washed up onto marginal environments. They die in the trillions. A few atypical specimens survive. Wait a couple of billion years, and a big assed dinosaur bites you in the ass.
Tris
Dogface, Viking - good points. Im beginning to think it was more of an accident than anything. Sort of like when someone says the average houseflies life expectancy is three days, yet you always seem to find the one in the windowsill that survived the entire winter. Can`t really be explained with any lack of ambivalence.