I once asked a similar question but this one zeroes in better on the issue.

Now that we know about genes and DNA we know living things evolve. They have to. At least a little. And I'm told that we can say the same thing can be said about sometimes evolving into a whole other species. It has to happen sometimes. The only real questions are whether everything evolved from something else and if something did, was it always the result of natural selection. I assume most scientist would say yes to both questions.

What I am wondering about is whether those yesses are due partially to the fact that they think there are no alternatives. As opposed merely due to the strength of the evidence.

Here is a precise question that should shed some light on this.

Suppose we somehow know that there is a race of aliens that visits exactly half of the planets in the universe that have DNA based life. They return every twenty million years. During each visit they mess with 5% of the life of that planet to change the course of evolution. Perhaps they relocate some of the animals. Perhaps they subject them to a bit of radiation. Or perhaps they do some genetic engineering.

They don't do anything extreme. But they certainly do change the course of the future. Their visits result in a living planet significantly different than the one that would have developed if they never visited. Including the creation of different beings.

Given 50% of planets with DNA life had this happen to them and given what we know about evolution on Earth, what would be the probability that this planet is one of those the aliens visit?

50/50

In this case, it holds true.I can only assume they don't do anything extreme in order for it to be undetectable to the life forms on that planet. Otherwise why would they show such constraint? We can know that certain life was wiped out by a meteor, but was it actually the aliens throwing a wrench in the system?

I don't see how anyone could claim to know with any certainty that anything found about the process has been done by aliens - any more than I could say that I did it, and try proving I didn't.

Disclaimer: I'm not a deep math guy so I could be missing something obvious here. This is just my initial thought about it, and I look forward to hearing what others have to say.

Lowish. Maybe 5% and dropping. The longer it takes the dog to bark, the bigger the chance there is no dog after all.

You did not add the condition that the aliens were trying to hide themselves.

Ever consider writing Sci-Fi big Dave? Put me on pre-order for your first book as long as it is less than $20.

I think you would maybe get better responses in SMP.

Regarding Splendour and I: Can we add DS to this?

I'd probably assign a >50% likelihood that we've been tweaked, but I'd probably be biased as ****. Scientifically, I don't think there's a solution other than to gather more information. Until then, 50% is the only justifiable conclusion.

They are based on a massive body of empirical evidence. Fossils, labtests, biogeography, etc. etc.

The question about the aliens isn´t really interesting, because it´s based on a faulty understanding of natural selection, if I understand the reason behind the question right. Evolution is simply about survival of the fittest, the individuals who are most successful in their current environment, under their given circumstances, get to pass on their genes. The aliens would be part of that environment, they can tinker how much they want, it´s still natural selection.
Replace aliens with a milkfarmer. The farmer will have complete control control over which cows reproduce. Cows who produce a lot of milk will get to have calves, cows who produce none will be sent to slaughter. This is still survival of the fittest, of those who are the fittest in this specific context.

And if you ask the question about the aliens in order to find out if there are species that can´t be explained by natural selection, there isn´t. Proponents of intelligent design have kept trying to come up with such examples for years, and still haven´t managed to come up with any that biologists fail to explain.

fivefingers is exactly right about your aliens example, in that what you're specifically saying wouldn't affect the theory of evolution, because conditions change for no good reason all through history which changes the dynamics of evolution. whatever the aliens did would be no different than a meteor hitting or an earthquake changing the flow of a major river.

unless what you mean is that no new species at all ever formed via evolution, but aliens would come down and zap us with a laser that made new species form but we are only capable of forming new species when we get zapped. i believe this theory is creationism. and yes, i think there being no alternate theories does matter, but i see it as a small piece of evidence which bolsters evolution, not as a fundamental piece of evidence for evolution.

Less than 10% imo.

I only have a BA in biology but I worked in a genetics lab for 3 years.

The way cladistics based on DNA sequencing fits together so nicely with the fossil record and carbon dating is evidence for evolution from a single common ancestor occurring naturally.



Essentially, the more different two species' genomes are, the further apart they will be on the cladogram. Further, if we know the rate of mutation we can estimate the amount of time two species have been evolving along different paths.

It's not a coincidence that the genes most vital for life (ones that regulate cell cycles, copying of DNA, and repairing of DNA damage) are conserved with relatively few changes throughout all life on earth.

so is the human race as we know it evololving into a differnt race? what will that race be called?

humanous evolous.

Any other questions you have about the future? I can only see ahead in time for 10 mins at a time once a year so clock is ticking.

Lets keep it a mystery ... more exciting that way

then where did the aliens come from?

I don't know how massive the effect of a mutation could be, but it seems statistically impossible to me for the Earth to hold only one species with brains so complex to handle abstract concepts, metalanguage, imagination, time and death figuring aso - only by means of pure and linear evolution.
There must have been something unique which acted only once; it was not a natural occurrence and it was probably consciously directed towards boosting human thinking abilities. I am not pointing to some God or else, but neither I have the scientific knowledge to make a viable hypothesis.
The alien explanation could be a reasonable one, but I don't think they would do such things on a regular basis - simply because there is no time in the Universe, there is space/time (when watching the sky, we actually watch back in time) and there is no way someone out there could make its mind to come back here "in 20 million years". Plus, if we use all our collective imagination for 100 years from now and we'll still be far from figuring the changes in a civilization's agenda during 20 million years.

This is illogical.

I think OP should read up on the productivity of presupposing un-nessecary plentitute.

That can't be right. There have to be thousands of creatures who have attributes that we don't know what pressured them to develep those attributes.

can you elaborate please... along the lines of how it fits to what you quoted... im confused but interested

This is the correct response. What we need is an Unhelped Helper.

I'd say the answer is pure speculation unless we have something else to observe. Find me two other planets with life on them, one tinkered with and one not, then I'll attempt to formulate an educated guess.

The fact of the matter is, there will always be tons of unexplained steps in evolution, because fossil records will always be woefully incomplete in many cases. (Note that this doesn't, in itself, justify the existence of God, it tilts me like crazy when Intelligent Design folks say, "Yes, science is good and right! But see over there, where science can't explain things yet? That's where the magic - erm, God - happens, baby!")

Even given a perfect fossil record, I'm not sure it'd be possible to tell if everything was "natural" or not - random mutation can do some pretty weird stuff.

May look illogical - I hope it's not. What I mean is: reason is the only attribute not shared by at least two different species - out of millions or more. Any other characteristic of DNA life is common to at least several different species. Reason (superior thought, capable of envisioning abstract concepts and future events like infinite, death, philosophical ideas, complex EV scenarios, intricate science concepts) is shared only by humans by an unnaturally huge margin. We handle a much better tool than necessary for the mere survival in the ecosystem. Abstract reason is useless in the economy of usual biological survival devices created by nature. Intelligence is a huge and unexpected bonus with no precedence in nature. Let's name another single item so oversized and excessive all over the biosphere. I doubt we could.
This singularity, unusual for the nature's scarcity and utility principle, requires a different answer than "why claws?", "why jaws?, "why venom?", "why wings?" aso. It leads me to suspect a deus ex machina intervention for reasons we could not yet figure out.
I don't think an objective God - if one in this Universe - would transform the world into a bluff by intervening to better it and hurry a natural process - by touching one of its beings with the magic wand of superior thinking.
There must have been something else. There must have been a reason for this and a further plan, according with this action.
Of course, I don't know what the power of a natural mutation is and of course, the Anthropic Principle tells me it's all natural (I couldn't have asked all these questions if it hadn't happened this way).
Sorry for my English, I am not updated for such dialogues, I've recently learned it from poker books

I think the popular theory for this is that these abilities evolved in humans simultaneously with the ability to walk upright and use tools.

Not having to walk on their hands freed our ancestors to develop fine motor skills. The ability to use tools effectively suddenly became positively selected for. This led to bigger and better brains being selected for more aggressively than they are in our ape cousins, which in turn led to all of the mental faculties that seem to be unique in humans.

Right, I know this inference, it's classic. I don't intend to argue against. It's just that I suspect it is not enough. The leap is too fast and too dramatic and somehow useless to having been required by the bear necessities of mere survival. It's very difficult for me to incorporate - for example - the Principle of Uncertainty into the collection of useful things a piece of living meat needs even to dominate the rest of the species. This principle is hugely superfluous in the present order of things, it's not a must have now and 10 million years from now if we consider what happened in the past 100 million years with life on Earth. It may still serve another goal. Who knows: maybe life is just protecting itself from destruction, providing the means for getting out of a doomed planet.

Not really. But the important thing is to always be able to argue how an attribute could have evolved, according to the general principles of the survival of the fittest. But to know every parameter of all circumstances for all species, for all of their history, is of course impossible, and not necessary either.
But as soon as ID-proponents can come up with an example that can't be explained, then that would be a problem. So far that hasn´t happened, however.

The way you define reason it´s not very stange at all that there is only one species that displays such a level of it. When a species becomes this intelligent, they will likely completely dominate their niche, and wipe out any competition - which is exactly what happened with the neanderthal, I think. As far as I know, they displayed similar levels of intelligence, with advanced tools, funeral rites, etc, but were wiped out, through direct warfare, or competition

There are certainly species that are close to having comparable intelligence though, bonobos, chimpanzees, gorillas and orangutans. And should humans be wiped out, I don´t think it´s unlikely they would evolve to fill our niche, planet of the apes style.