It varies. Random mutation is random, and natural selection can occur rapidly or slowly depending on the environment. Evolution through natural selection is not a process to get you from simple to complex, it is a process that gets from not well adapted to reasonably well adapted. Sometimes complexity cobnfers an advantage and is perpetuated, sometimes it is a disadvantage and the complex line dies out.
I point out that for 75% of the history of life on Earth, only single celled organisms existed, and they are still by far the most successful lifeforms by any biological measure.
What change in environment would be needed for single cell organisms to become multicellular? Or if it happens by chance alone then how complex is the process in which the multicellular organisms duplicates? (cause the most simple multicellular organisms surely doesn't have to mate? - and if it does have to mate, then how many cells are the minimum for that?)
Evolution is constant and is not confined to one trait at a time. But your question is flawed. If the environment changes so that an organism cannot live the way it has in the past, then evolution does not "compensate" sio that it can go back to doing things the way it used to. Evolution does not care about the way things used to be done or the form and function a species had in the past. if the environment changes so that a lifestyle or feature is now maladaptive, those features will disappear and the organism will either adapt to a new way of living that works with the new environment or die out.
I didn't think evolution would somehow compensate to go back to how things were before - even if I do think that the former state of an organ would be more easily accessed than a totally new state, as much of the information for the former state probably still is available in the DNA.
No. Evolution of the human brain is an adaptation to be sure, but it is not the end all be all adaptation that make us the best survivor. The brain is expensive, it uses up a huge number of calories per day and requires difficult to obtain protein to grow and sustain it. In a severe environmental cataclysm, there's good reason to believe that the large thinking brain would be a disadvantage because it is a resource hog.
That is; if the intelligence we have doesn't solve the problem, in which evolution wouldn't be needed, if we have enough time to solve the problem, then the brain is superior, but if we don't have enough time, so that many people dies and only a few is left, then we probably don't have the "manpower" to solve the problems ourselves, and the brain wouldn't be needed as much.
Even assuming that the environment never changes it is unlikely that we'd become the only species left in any reasonable time frame. We eat other species opf plants and animals. It is hardly reasonable for any animal to allow a Soylent Green situation to develop when it can foresee the trouble in advance.
Much like wolves and mountain lions (superior killing machines) did not come to kill off all the herbivores in North America, though, we would not be able to entirely destroy our food supply before that fact negatively impacted our own numbers. As with a predator-prey interaction, one can expect a certain dynamic equilibrium to form.
Hmmm, I agree.
Yes, certain other species were more abundant in the past. Mountain lions and wolves to return to those. By thinning their numbers we have made it less likely their populations would survive a serious environmental change. Insects are harder to judge. Those that feed off humans are (like roaches) far more common that they were in the state of nature). Roaches, despite out trying to kill them, thrive more than ever in the human fiulled world because they can live off our detritus.
Do you think it's reasonable to think that we will at one time create a situation where it is beneficial for all to "live together" in symbiosis? Or that a situation will occur in other ways in which we all live in symbiosis?
There is no number. A single organism that reproduces asexually can evolve For those who believe that life has a chemical origin likely evolution started with chemical evolution, before there were any real "species".
Can you elaborate in which form a chemical could evolve? ...and for what reason? What would be the constraints?
I do not follow. But look, evolution is not conscious it does not think or hope or design or plan or want. Anything that alters the mix of factors that make to reproductive success can affect evolution, including mankind's actions. Natural selection no more wants to use one species to change another or wants to change a species than a river wants to make rough stones smooth or gravity wants to make ripe apples fall.
I didn't mean to imply that I thought evolution thought of us as a concurrent, but that we in fact were a concurrent to other species adaptation to the environment, by helping them (making the gap for transitional environmental change larger and larger - and harder to overcome).
Again, desire is irrelevant. Evolution was not trying to produce humans, humans are simply what happens to have resulted from evolution. Evolution also has no plan for what we will evolve into. That too will be just something that happens and it is something that could happen in millions of ways. We could all evolve back into isingle celled organisms. It is unlikely, but evolution doesn't care.
Even though evolution "doesn't care", life is still self-sustaining, and if there were a way to know what way to adapt or what pieces of the DNA to make weaker or stronger in order for them to adapt more easily to a changing environment because those pieces might produce results that fit better whatsoever the change might be then that is a preferred way and this is the kind of changes that would hard for us to see as they are more subtle. The attraction between males and females is also one place to make changes if to prepare for future adaptations.
Are we talking about evolution or selective breeding ?
Evolution. Millions of years of evolution.
The fact that you called them rules. Rules are there to keep entities from moving beyond arbitrary boundaries i.e. rules can be violated by definition.
The laws of nature cannot be violated.
Well, let's call them principles then.
I already gave an example. The weaker parts of the DNA are more easily changed, in a long timescale it would be beneficial for a lifeform to relate the DNA that are more easily changed to the adaptations that would be needed for environmental change, even if that weakness is subtle, there could also be repair processes that would solve known errors (I know there is such processes already) that changes might produce in order to lead it to a beneficial change.
Still, I don't find that hypothesis remarkable. We discovered new ones in the last 100 years. There could easily be a few more that we haven't found yet. We still haven't been able to find a relationship between gravity and the other three fundamental forces; there might be a new law lurking in there. Ditto for string theory, or whatever is taking its place. Which I suppose will include gravity, won't it?
