I have read bits and pieces on evolution and its theories.

If someone could simplify it and tell me in a way the average person understands I would be grateful.:)
Also how much of it has been proven without doubt and how much remains to be researched?
Also if you could give examples of archeological evidence (if any:) ).


Thanks all:)

Try this: Evolution - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Evolution)

Thanks CB, I have looked through that, but there are too many scientific terms to comprehend.
I will read through it once more though...

In a nutshell, the theory is based on Darwin's theory of Natural Selection or survival of the fittest. Darwim believed that the best traits would rise to the top and others would fall by the wayside. So life would evolve as mutations resulted in evolution of the species.

In a nutshell: variations occur from one generation to the next due to genetic mutations. Usually such mutations are bad - the offspring may die before it has a chance to have babies and pass the mutation on. But once in a great while a mutation may actually improve the chances that the offspring will survive and have babies of its own. For example, consider the case of a bird whose baby has a particular mutation that makes its beak stronger, or longer, and thus it is better able to forage for food than its parents or other siblings. That bird is more likely to thrive, have babies of its own, and thus the mutation gets passed on to subsequent generations. This is the theory of natural selection - those mutations that result in more babies tend to be passed on; those that don't, don't. Pile more and more mutations on over thousands of generations and you can find that the descendant of that original bird have diversified into multiple species.

The archaeological evidence is overwhelming. From the fossil record it's possible to trace the continually-changing march of species. Just one example - the rise of the dinosaurs starting 250 million year ago and lasting up until about 65 million years ago, at which point mammals begin to dominate. There are no fossils of modern mammals that date to the age of the dinosaurs - firm evidence that mammals evolved after the dinosaurs. Also, as time progresses, the fossil record shows more and more diversity of animals - more species - as expected.

In a nutshell, the theory is based on Darwin's theory of Natural Selection or survival of the fittest. Darwim believed that the best traits would rise to the top and others would fall by the wayside. So life would evolve as mutations resulted in evolution of the species.

I thought I read somewhere on this forum that Darwin's theory was not the same as what is evolution that is being talked about today... am I right or am I wrong?

Thanks ebaines for your explanation...

The full name is the Theory of Evolution by Natural Selection

the full name is the Theory of Evolution by Natural Selection

Is that the same as the original idea presented by Darwin or has it changed in anyway since then.
The natural selection part etc.

From my understanding Darwin proposed this theory because he saw some animals more adepted to certain environments than others, am I wrong in my understanding?

Thanks Scott

There may be tweaks in the thoery since Darwin wrote his book. But the essential points still stand.

Is that the same as the original idea presented by Darwin or has it changed in anyway since then.
The natural selection part etc.

From my understanding Darwin proposed this theory because he saw some animals more adepted to certain environments than others, am I wrong in my understanding?

Thanks Scott
Natural selection - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Natural_selection#Darwin.27s_hypothesis)

Here's one readable source that I like:
Evolution and Natural Selection (http://www.globalchange.umich.edu/globalchange1/current/lectures/selection/selection.html)
Enjoy.

I thought I read somewhere on this forum that Darwin's theory was not the same as what is evolution that is being talked about today...am I right or am I wrong?


The fundamentals of what Darwin espoused is still the basis of modern evolution theory. Keeping in mind that Darwin worked 150 year ago, there have of course been many refinements to his original theory over the years. For example, DNA was not discovered until almost 100 years after his work, so of course Darwin had no understanding of the mechanics of how mutations are passed on at a molecular level. His original thesis was that all changes over time are accounted through natural selection ("survival of the fittest"), but in the 1960's a companion theory emerged called the neutral theory of molecular evolution which states that many genetic changes have a neutral effect on whether the animal successfully procreates, and hence may get passed on to subsequent generations even though they neither help nor hinder the animal's fitness. Hence over time many portions of the genome evolve that do not express any particular functions - hence the term "neutral." More recent advances talk about "nearly neutral" mutations, which may have a very slight advantageous or deleterious effect on the animal's fitness. The discussion is really not around whether natural selection was right or wrong, but rather around the relative percentages of "neutral" versus "non-neutral" alleles in the genome.

In the same way that you have read and studied the qu'ran (sp?) you will need to do some reading and studying to understand the science behind the theory. Not sure you can pick it up in bits and pieces here.

Natural selection - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Natural_selection#Darwin.27s_hypothesis)

Thanks NK,
As I told CB, I have tried wading through the explanation on this link and others and half way down I get confused because it uses so many scientific terms and I get lost along the way.

One of the reasons I asked this question, the other was because someone on another thread suggested that evolution be discussed separately and not on someone else's thread.

So here we are and I would like a simplified explanation like some of the above...

Thanks all

In the same way that you have read and studied the qu'ran (sp?) you will need to do some reading and studying to understand the science behind the theory. Not sure you can pick it up in bits and pieces here.

Sorry to sound dumb,but what does (sp?)mean?

I was hoping to be able to at least know what evolution is,enough to satisfy my curiosity.

And the evolution theory and studying the Quran is not in the same level of importance for me, but science as I said before helps me with my faith(by showing me that what I learn in the Quran is the truth).

And by knowing evolution I am not hoping to give up my faith or look for another belief, I am secure in it and wish for no change, only understanding.:)

(sp?) is the editing symbol for "unsure of spelling".

Side note. Does not the Quran also contain the creation story of God creating the world in 7 days? Why don't the Muslins and Jews join many Christians in questioning evolution? My opinion is that the 144 hour time table is not the only possible understanding of the Bible. Just as most Christians accept the earth revolving around the sun now, I think they will eventually accept an older earth.

The earth does appear to be more than 6,000 years old. I understand natural selection, but still don't see how species can gradually become unable to interbreed.

The earth does appear to be more than 6,000 years old. I understand natural selection, but still don't see how species can gradually become unable to interbreed.

Labman: if you are willing to accept an earth that's older than 6000 years, are you also willing to acept that there are species alive today who have not been around for the full duration of the history of life on earth? For example, the fossil record shows that few mammals were present at the time of the dinosaurs, and certainly none that we would recognize today. Isn't it therefore logical that mammals such as cats must have ancestors who were something other than cats? That is, they must have evolved from some prior species, no?

Some find this of interest:
YouTube - Carl Sagan - speaks about 4 billion years of evolution (http://www.youtube.com/watch?v=pMHNnhAEDN4)

Side note. Does not the Quran also contain the creation story of God creating the world in 7 days? Why don't the Muslins and Jews join many Christians in questioning evolution? My personal opinion is that the 144 hour time table is not the only possible understanding of the Bible. Just as most Christians accept the earth revolving around the sun now, I think they will eventually accept an older earth.

The earth does appear to be more than 6,000 years old. I understand natural selection, but still don't see how species can gradually become unable to interbreed.

Qur’an mentions that the universe was created in six ‘Ayyaam’. ‘Ayyaam’ is the plural of ‘Yaum’ which has two meanings: firstly, a standard twenty-four hours’ period i.e. a ‘day’ and secondly this Arabic word also means a stage, a period or an epoch consisting of a very long period. Here the Qur’an refers to the creation of the heavens and the earth in six long periods or epochs.

The bible never says that the earth does not revolve around the sun.
It wasn't christians who believed that, it was everyone
I will admit that the catholic church of those times did often try to suppress new ideas, and made many other mistakes. If the catholic church hadn't opposed science so much back then, maybe the scientist and the christian wouldn't be so hostile to each other nowadays, and more accepting of each other.

What language does the qur'an origionally written in? Maybe there's a similar way about the original language of the bible, explaining the 6 day issue.
And hey, a day isn't always 24 hours. If you look in joshua, you'll see that god made the sun stand still and the moon stand still (thats the human witnees interpretation, maybe god just adjusted the earths orbit/spin temporarily to achieve the same affect) so that the battle could be finished
During the creation, gods 6 days could have been any kind of days he wanted them to, he could have slowed the orbits and stuff, giving himself days lasting months, years, even millennia for him to work in.

the bible never says that the earth does not revolve around the sun.
it wasnt christians who believed that, it was everyone
i will admit that the catholic church of those times did often try to suppress new ideas, and made many other mistakes. if the catholic church hadnt opposed science so much back then, maybe the scientist and the christian wouldnt be so hostile to each other nowadays, and more accepting of each other.

what language does the qur'an origionally written in? maybe theres a similar way about the original language of the bible, explaining the 6 day issue.
and hey, a day isnt always 24 hours. if you look in joshua, youll see that god made the sun stand still and the moon stand still (thats the human witnees interpretation, maybe god just adjusted the earths orbit/spin temporarily to achieve the same affect) so that the battle could be finished
during the creation, gods 6 days could have been any kind of days he wanted them to, he could have slowed the orbits and stuff, giving himself days lasting months, years, even millenia for him to work in.

Quran is originally in Arabic...

Thanks for the link to this thread, firmbeliever.

I hope our discussion in the other thread has given you a better understanding of how natural selection works. One thing which might help you in that understanding is to remember than humans are animals - we're just at the top of the food chain. We're the smartest, the most advanced, but really, we're just animals.

Here's the link to the thread for anyone who wants to see where the conversation went:
https://www.askmehelpdesk.com/biology/evoloution-theory-131048-10.html

Before we continue further I would just like to let you know where I stand on this theory and this article agrees with my views.
Islam Tomorrow .com (http://www.islamtomorrow.com/science/)

And I believe that Adam(alaihi salaam) was the first man.
Now this does not mean that I do not agree or disagree with other beings similar to apes existing before Adam's existence.

I understand how natural selection works.

I am not too sure about the human being an animal part.
I think since "human" beings began we have been the same, with a conscience and a brain that works much the same like our present day humans.
Just the progress in technology and science seems to aid this intelligence in progressing today's human beings.

When I really think about it, sometimes I feel that the older civilisations without today's technology had progressed quite far in their methods of buildings,astronomy,languages etc

I can relate to the part where the earth formed and living creatures formed and grew in number and types.
But now that I think about it I am wondering did the dinosaurs exist between the first animals and the modern day animals?
Did the animals grow that big and then start to become smaller as the earth aged?

I might sound a bit off at times,but that is just how I am processing and digesting information.

Ok, let me try this another way, and if there are things in here you already know and I'm putting it too simply, I'm not trying to insult your intelligence, but it helps me be able to explain it step by step!

If you have to classify life on this planet you have plants and animals, right (for simplicities sake)? If I show you a picture of a tree, you and you have to pick (A) Plant or (B) Animal, you pick (A). If I show you a picture of me and tell you to pick (A) Plant or (B) Animal, what do you pick? Human is just another type of animal. We know that because of they types of cells we have - we don't have plant cells, we have animal cells. For a graphic representation, see the link below.

plant and animal cells (http://sun.menloschool.org/~cweaver/cells/)

ALL animals have cells that look like that first picture. A snail, a fish, a toad, a human. All plants have cells that look like the second picture. That's why humans are considered animals. Now, perhaps you already know this (in which case I'm not trying to insult you), but because of your beliefs you think we are better than animals. That's fine, and really, it's true. But on a cellular level, we are still animals. Other things set up apart from other animals; brain size, capacity for planning and reason, reflection, speech to name a few examples. Obviously we are the "best" animal.

When you say the first "humans" were pretty much the same as we are today, you're right. I know your religion tells you Adam was the first man (human) but in evolutionary terms, you don't call a human a human until he's a homo sapien. Homo sapian looked like this:

Google Image Result for http://www.theage.com.au/ffximage/2005/03/18/evolution_1903_wideweb__430x328,1.jpg (http://images.google.com/imgres?imgurl=http://www.theage.com.au/ffximage/2005/03/18/evolution_1903_wideweb__430x328,1.jpg&imgrefurl=http://www.theage.com.au/news/Science/Skeletons-in-the-cupboard/2005/03/18/1111086008084.html&h=328&w=430&sz=35&hl=en&start=3&um=1&tbnid=TpNuOiKSNdc07M:&tbnh=96&tbnw=126&prev=/images%3Fq%3Dhomo%2Bsapien%26svnum%3D10%26um%3D1%2 6hl%3Den%26rls%3DGGLR,GGLR:2006-28,GGLR:en%26sa%3DN) (guy #2 in the lineup).

Before homo sapien, we weren't "human" we were other things (usually referred to as early man). That first "human", it appears, DID think in similar ways to us, and yes, technology has allowed us advancement. And indeed, ancient civilizations progressed amazingly with regards to the limited technologies they had. I don't know if you've ever been to an ancient ruins site, but they are incredible. Take the great pyramids, for example. I've never been, but the construction and precision is amazing. It's mind boggling that man did that without the aid of so many modern conveniences when today we think the world will end if the cable goes out. But man didn't get to that state without work. The first humans still had to compete for food, shelter, a place in the community, safety and so on. At that time, natural selection was still taking place. Early human was still trying to create the best race they could.

About dinosaurs, obviously I can't give you guidance to the Islamic belief there, but from the archeological evidence we have, dinosaurs did not exist with man - at all. So yes, dinosaurs existed between the first animals (the ones crawling out of the primordial ooze) and present day animals (cats and dogs). If, in fact, there was a large volcanic eruption or asteroid impact that caused the death of the dinosaurs, this didn't kill ALL the animals on earth. Mammals, especially the small ones, survived. Those mammals reproduced and evolved into what we find today. Bear in mind this was 65 million years ago - that's a long time. Early man (and later modern man) came out of that evolution. Again, there is absolutely ZERO archeological evidence that man existed with dinosaurs (this is a common thought among some).

Jillian,
Just to get things right.

I am still reading your answer and thinking over it.
But wanted to thank you for the detailed simple explanation.

I agree with the animal part when you put it under cell structure,of course we cannot be plants.

About dinosaurs, there is nothing in the Quran that says humans existed from the beginning of earth/universe.
But I do remember a verse which mentions that there was a time when man was nothing to be mentioned of(not in the same words,but same meaning).

I like the video that Carl Sagan and crew did:

YouTube - Carl Sagan - Origins (http://www.youtube.com/watch?v=DBBh-o_9XWE)

Give it some thought...

When you say the first "humans" were pretty much the same as we are today, you're right. I know your religion tells you Adam was the first man (human) but in evolutionary terms, you don't call a human a human until he's a homo sapien. Homo sapian looked like this:

Before homo sapien, we weren't "human" we were other things (usually referred to as early man). That first "human", it appears, DID think in similar ways to us, and yes, technology has allowed us advancement. And indeed, ancient civilizations progressed amazingly with regards to the limited technologies they had. I don't know if you've ever been to an ancient ruins site, but they are incredible. Take the great pyramids, for example. I've never been, but the construction and precision is amazing. It's mind boggling that man did that without the aid of so many modern conveniences when today we think the world will end if the cable goes out. But man didn't get to that state without work. The first humans still had to compete for food, shelter, a place in the community, safety and so on. At that time, natural selection was still taking place. Early human was still trying to create the best race they could.

Again, there is absolutely ZERO archeological evidence that man existed with dinosaurs (this is a common thought among some).

So I can safely say that the first "human" was Adam(alaihi salaam).

Could it be possible that these other "early man" were not really human beings as we are,but another animal with similar structure and these went extinct like other animals?
And like apes having a similarity in dna, these animal like man also had similarities to humans?

About dinosaurs not being around at that time humans started living on earth, I agree with this because the universe began long before man existed on earth and the earth has to have taken ages/eons to become what it is today as a planet.

If you want to call the first human "Adam", go for it. It certainly fits in line with your religious beliefs, and since you acknowledge the existence of other, early man creatures before "Adam" this isn't wholly inconsistent with the scientific view. As you know, science says "Adam" evolved from early man, but I know it is not your personal belief that this is the case.

The reason in science early man is considered (in general terms) human is because that's where we came from - that's the line of evolution. I don't know enough to say with any authority that the dna structure of early man is the same or XX% the same as our current dna, so I'm sorry, but I don't have an answer for that. I have a feeling looking it up would mean wading through a lot of scientific jargon, too!

Glad we agree people weren't dining on T-Rex steak! :)

Glad we agree people weren't dining on T-Rex steak! :)

My faith is a bit more compatible with science than you think:)

I have a question again on this topic.

I read somewhere that life began in water, then the land mammals changed into whales or other large fish and these evolved into modern whales.

Is this proven fact or is my information wrong?
I am wondering why did not the sea creatures change into whales,why did land animals change into whales?

Thanks again.

I would have thought that the 'sea creatures' couldn't breath oxygen as it were and so could evolve into whales as they are today?

Is this proven fact or is my information wrong?Hello firm:

Here's where I think you're going wrong. NONE of it is proven fact.

It's probably true. It looks like it's true. Modern biology says it's true. I think it's true. Capuchin thinks it's true. So, of course, it IS true.

It remains, however, a scientific theory. We have not yet filled in all the gaps. We may NEVER fill them in. We have a LOT to learn in ALL the sciences. As a matter of fact, we're just in the beginning stages of understanding our surroundings. If knowing nothing is a 1, and knowing everything is a 10, we're probably a 2.

excon

Excon,:)
2 it is!

But still would like to know where if there are any findings to connect land mammals to whales and not the other way around.

Hello again, firm:

I know SOOOO little about it, I'm probably an expert. Here's what I think.

The things that cause creatures to evolve are isolated populations, time, and unanticipated mutations.

We (you and me) are mutating daily. We really are. Yours and my genes are being bombarded by cosmic rays from space. I'm not kidding. Yes, I'm being a little dramatic, but we're all mutants in one way or another.

Some of those mutations wind up changing things for the BETTER, and they get duplicated in our offspring. Seeing as how its BETTER, the beings having the BETTER gene are BETTER able to survive, and so they do.

Now take a population of mammals who are isolated in some pocket of land. Maybe they're surrounded by mountains. Let's say the sea is rising (which is does and has lots of times). Let's say one of these mammals gets mutated in a way that allows him to adapt to the rising sea BETTER than his buddies.

Now, give that situation a few MILLION years to percolate, and you have land mammals turning (evolving) into whales. I don't know if it happened that way, but I'll bet it did.

excon

Evolution goes both ways.
Some creatures move from water to land and some from land to water:
Walking fish - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Walking_fish)
The diving Petrel and auks "fly" underwater. Peguins are another good example.

The basis behind this is that whales are mammals. Mammals are air breathers. So it would seem logical that mammals that live in a water based environment evolved from land based creatures.

But, as excon said, without a time machine that can watch the creatures evolve, none of this can be proven.

Evolution goes both ways.
Some creatures move from water to land and some from land to water:
The diving Petrel and auks "fly" underwater. Peguins are another good example.

I have seen a documentary about those walking fish.It was very interesting.
They also showed an episode about frogs that hibernate in the ground during the very dry season and come out when the rainy season arrives.

I loved the auks under water documentarytoo,it was beautiful and amazing. There was one on penguins too, how they look for food under the ice sheets floating in the icy waters.

Thanks for the link.

Scott,
How about amphibians?Were they supposedly in water before adapting to land or the other way around?

I read somewhere that life began in water, then the land mammals changed into whales or other large fish and these evolved into modern whales.

Is this proven fact or is my information wrong?


These are big questions, but you have it right. Life most likely originated in water. Biologists are pretty sure about this, but not completely. In a way, that part's conjecture. I mean no one knows for sure when and where and how the first cells originated---the actual origin of life.

But once the first cells appeared, biologists do understand how those cells evolved into all the millions of species that have lived on Earth. Biologists understand how new species formed really well. In other words, it's "proved" as much as anything can be in science.

The cells living in water evolved into invertebrates--things like sponges, jellyfish, and starfish. Later, fish, which have backbones ("vertebrates"), evolved. Some of the fish evolved into amphibians that could live partly on land. Amphibians have to reproduce in water, so they are like fish that way. But some amphibians evolved something called the "amniotic egg"--basically like a chicken egg. All the reptiles and birds have amniotic eggs, which allow embryos to develop inside a kind of miniature pond, encased in a shell, all on dry land. It was a great invention. It let vertebrates start evolving on land instead of in the water. Some of the reptiles evolved into mammals. Mammals kep the amniotic egg inside the body, instead of laying it in a nest like a reptile or a bird.

SOME of the mammals that lived on land returned to the water and evolved into water mammals such as whales or sea lions or seals. That's definite and well understood. You can tell a lot about which animals evolved from which other ones by looking at their bones. So, for example, the bones in the hips of dinosaurs look a lot like the hips of modern birds, one way we know that birds are actually descended from dinosuars.

Hope this helps some.

Asking

I am wondering why did not the sea creatures change into whales,why did land animals change into whales?

Thanks again.

Why certain animals evolved into other ones is a hard question to answer. And some people have done a good job trying to explain it simply in this thread, but I'll try too.

We can guess that land animals were under some kind of pressure a long time ago. For example, if they were already living by the shore and eating fish and they couldn't find any food on land at all any more, they might have had to spend more and more time fishing in the seas. Or maybe there were dangerous predators on land and they had to spend more and more time in the water to be safe.

If they were already behaving that way, spending lots of time in the water, then the individuals that had mutations that made them swim better or hold their breath longer--stuff like that--would have had more children ("offspring") and the next generation would have had all these "better" mutations. The mutations aren't really "better." They are just better for swimming, better for being in the water all the time. These things just depend on what the situation is. Anyway, these particular mutations that make it easier to spend a lot of time in the water got passed on because, at that time, swimming was a better way to go.

Here's a real example. Biologists have looked at Galapagos finches. They found that when the weather changed, plants that made big seeds did better and plants that made small seeds did worse. All of a sudden, the birds with big beaks started surviving and reproducing better (more baby birds with big beaks) than the ones with small beaks. This was because the birds with big beaks could eat the big seeds, while the birds with small beaks were going hungry and not able to make babies. So over just a few years, the average beak size of this species got measurably bigger. That's evolution. That has actually been measured.

If the change in beak size continued for a while and if the big beaked birds stop mating with any remaining small big beaked birds (which could happen), then you could have a new species of finch.

Wow! We just had a big earthquake...

Asking

Asking,
Thank you for the explanations.

About the Earthquake.
Are you serious?Was it a big one?Are you OK?

Just reviving an old thread,hopefully to have some more information I might have missed out there.:)

Firmbeliever>I can relate to the part where the earth formed and living creatures formed and grew in number and types.
But now that I think about it I am wondering did the dinosaurs exist between the first animals and the modern day animals?
Did the animals grow that big and then start to become smaller as the earth aged?


There is plenty (relatively speaking) of fossil evidence for the forerunners of dinos. They didn't all appear quite as reptilian. Time-wise, dinos appear quite late in earth's history. I saw that someone gave you a Carl Sagan link. It might have contained the 24-hr earth clock. In that analogy, dinos don't appear until after 11pm (I think). The environment, esp the atmosphere had a lot to do with evolution. There were once giant insects but they are restricted in size now because of the lower oxygen content than the giants had. There's also speculation that increased oxygen might have helped spur the Cambrian Explosion where diversity blossomed.

Besides atmosphere, location can afect size. Populations isolated on islands tend to get smaller (a now extinct pop of mini elephants was found on aS Pacific isle). I think someone else suggested isolation by other geographical features. This could affect size and diversity (less competition, less need for diversity).


Firmbeliever>So I can safely say that the first "human" was Adam(alaihi salaam).

Could it be possible that these other "early man" were not really human beings as we are,but another animal with similar structure and these went extinct like other animals?
And like apes having a similarity in dna, these animal like man also had similarities to humans?


You can call the first human whatever you like, but so far only 'Eve' has been located scientifically. <G> Using genetic studies of mitochondrial DNA (mDNA) which is passed only from women to their daughters, the human line was traced a few years ago to a single woman living in Africa. This doesn't mean she was the 'first,' but just the first to have daughters whose line continued to have daughters. (In 1997, I think the study's been updated to 7 'Eves' - book: The Seven Daughters of Eve by Bryan Sykes) Combining mDNA and studies of X genes, (men to sons) it's been shown that all the humans on Earth today started from populations in Africa. There was a good article on this in the July 2009 issue of Scientific American. (The lingo isn't hard for a non-sci to understand.)

Not all the humanoid fossils found are linked directly to us. There were apparently many species that came close but went extinct. Neanderthals are a good example. Their brains were larger than ours. They were more suited to the cold in 'Europe' but either because they might have lacked the creativity to survive changing environments or maybe their numbers were too small to maintain a 'breeding population.' We might have just out-competed them and drove them to extinction. (While the general consenses from genetic studies is that we didn't breed with these other species, it cannot yet be determined to any real degree of certainty.)


Firmbeliever>I read somewhere that life began in water, then the land mammals changed into whales or other large fish and these evolved into modern whales.

Is this proven fact or is my information wrong?
I am wondering why did not the sea creatures change into whales,why did land animals change into whales?


Others have done OK in explaining this. Whales provide one of the clearest examples of evolution. Fossils have been found (some in the Himalayas) that show the progression of losing legs, changing nostrils from front of snout to top of head, etc that show the evolution from land to water. Whether life started in the water isn't yet known, but it's the most 'logical' so far from our understanding of early Earth. But extremophiles - life forms that live in places where we didn't used to think it could survive - make just about any environment a possible starting place. (Examples are bacteria and fungi that live in places like Yosemite's hot springs, or normally chemically hostile bodies of water.) Someone mentioned the 'smokers' on the sea bottom at the Atlantic ridge - where the 2 plates join and magma and associated gasses bubble up to form more seafloor. No sunlight reaches these and the temp and chemical make-up is hostile to most life. Yet there are thriving communities with surprising diversity living on these hostile 'chimneys.' With the early Earth possible similar to these areas, that's where life may have started and they might not have needed that much water and obviously don't need the Sun.


_


Jillianleab> Obviously we are the "best" animal.


"Best"? I'm tempted to say something about hubris... We're not the 'best' by many definitions. We've probably even slowed our own evolution since we've stopped adapting to our environment and change the environment to suit us instead. This may lead to our downfall as the supposedly dominant species if we stop adapting - at least since we've changed the environment a bit too far... :rolleyes: 'Best' and even 'most intelligent' are relative terms.


_

Firmbeliever, try the following site. It's main purpose is keeping the science in science in classes. Fundamentalists don't like it for that reason, but they are not at all hostile to religion - as long as it doesn't try to disguise itself as science. There are many links and sources so you might find info useful to your quest.

National Center for Science Education (http://www.natcenscied.org/)

Good morning!
Lots of interesting discussion here. I wanted to comment on the idea that humans may have stopped evolving. Evolution is, by definition, change over time, but biologists include not changing, or "stasis," as a part of evolution. So, for example, cockroaches and horseshoe crabs seem hardly to have changed at all for millions of years.

Often, when a species doesn't change it is because, any deviation is selected against. That's called "stabilizing selection." So a cockroach that had purple wings would not be able to make any babies (for whatever reason), and so the mutation for purple wings would die with it. (I hope it's obvious I'm making this example up!) There's no change, but selection is still happening, which is a form of evolution. In fact, genetic change can occur as long as the phenotype--how the cockroach actually looks and behaves--doesn't change. Some mutations don't change the animal (for a lot of really complicated reasons). So if humans were experiencing stabilizing selection for certain traits, say intelligence (people really dumb and really smart having fewer babies, for example), then that trait would not change much. But that wouldn't prevent other traits from changing.

For natural selection to work at all, there has to be some genetic variability. So if a population or species were all genetic clones of each other, they couldn't change. Humans, obviously, are not all genetically identical. In fact, we are pretty variable genetically. Some populations of animals are much more genetically alike than we are. So on that basis, our having so much genetic variability, I know that we can still evolve and pretty much must.

Any time one person has more children than another, there is the potential for genetic change. There are lots of reasons for this to happen even today. For example, it used to be that women who could not deliver a baby died in child birth and the baby was more likely to die too. Even though some babies survived, the inability to deliver a baby easily was selected against. Ten thousand years ago, people with traits like narrow hips that made it hard to deliver a baby didn't have many children. Nowadays, women with that problem get a C section. So I would assume that in developed countries at least, the tendency to have difficulty delivering a baby might be increasing. That would be evolution.

In places like Africa, huge numbers of infants die of diarrhea every year, so it's safe to assume that any genetic resistance to diarrhea would give a person an advantage and such people would be more likely to survive and reproduce. I don't know if anyone has looked at these things. But given humans' great genetic diversity and the many deaths among babies and children before the age of reproduction, I would assume that natural selection and evolution continue today. No matter how much we change our environment, we still experience differences in reproductive rate and therefore evolution. The two factors that drive evolutionary change are genetic variability and differential reproduction (some types producing more offspring than others).

I'm not in favor of eugenics by the way. But that's another topic.
Asking

Thanks everyone for your thoughts and links.

I was just wondering(not sure if I asked this before.. )
I know that eco system exists which depend on one another making it a cycle of life.
For example there are live organisms within the soil which make the soil different depending on its work in it.And then there is what is contributed by animal and plant life to make the soil different which in turn helps things grow and get the animals their food.
And an eco system depends on one another to complete the cycle and make an environment habitable for all creatures.

Now my question is,when the evolving period is happening what could have happened to the eco system of that area where evolution is taking place,would there not be an imbalance of sorts?
For example if the worms within the soil are not eaten, then they grow in number and affect the condition of the soil which in turn would affect plant life etc.

Thanks again.

when the evolving period is happening what could have happened to the eco system of that area where evolution is taking place,would there not be an imbalance of sorts?
For example if the worms within the soil are not eaten, then they grow in number and affect the condition of the soil which in turn would affect plant life etc..

Hi Firmbeliever,
That's an interesting question, a good one, I think. I can think of two answers. First, evolution DOES affect local ecology. So if a worm evolves some kind of defense against a predator, and so the worms multiply and become more in number, that's going to affect soil, which will affect plants (which will affect animals). More worms could be good for some plants, bad for others. Who knows? These things are very specific. But the plants can evolve too and compensate if something is changing in their environment. And the worm eating predators also might find a way to over come something. Or the worm-eaters might go extinct because of a lack of food. Lots of possible outcomes for a single change like that.

But, second, I also want to say that even though evolution affects ecology--it is ecology that is the short term process that produces evolution. So the fact that something is eating the worms is the selection pressure that makes the worms change, or evolve (to continue with your example). What happens right now is ecology. When you look at ecology over time, it is evolution. It's like looking at the same thing in different dimensions, if that makes sense.
Asking

Thank you asking.

Here is an example of what I mean.
How the Pine Beetle is Destroying Colorado Forests | Newsweek Project Green | Newsweek.com (http://www.newsweek.com/id/148297)

The eco-evo-eco link is what led to the Gaia hypothesis - that the Earth itself is an organism. One idea on early diversity is that once plants evolved, they eventually created enough oxygen so that land animals/insects could evolve. At one point there was so much oxygen that insect were allowed to reach enormous sizes. They're limited today because of the way they breathe (thru 'skin') and there's not enough oxygen now for them to be any bigger (it wouldn't make it to enough of their bodies).

Insects, in turn, led to flowers - the plants learned to use the insects for pollination and so not all had to depend on wind or pther means to spread seeds. Kind of give you new respect for insects (except skeeters and fleas... <G>).

asking - you're right about the algae. I got typing faster than I was thinking. <G> They develop through photosynthesis and expel oxygen like plants.

Thanks for the correction.



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Thank you asking.

Here is an example of what I mean.
How the Pine Beetle is Destroying Colorado Forests | Newsweek Project Green | Newsweek.com (http://www.newsweek.com/id/148297)

You are welcome. :)

To me this sounds like global warming may be a factor, since the forests are dry and the summers are warmer and longer. That gives the beetles more time to eat and reproduce than if winter hit them earlier. Also, insect larvae are different from us in that they grow faster when it's warmer. So they may be getting a bit bigger and reaching maturity sooner, which allows them to breed more often in a season (if they do that). I don't know from beetles, but I studied other insects in college. This sounds really bad. :(

So, the beetles are selecting for beetle-resistant lodgepole pines. If any trees survive, they'll have some special trait that makes them different from the other trees. This is heavy selection pressure and will certainly change the trees. But in the meantime, the whole ecology of these areas is going to change for the time being. The trees may come back in 100 years, but no way to know now... Meantime, you'll have a different kind of vegetation, some other trees, maybe brush or grassland if the trees really are killed en masse, as this story suggests (which I don't know). We still have lodgepole pines in California. They were hard hit in the 70s by beetles, and the government sprayed the forests with insecticides. They look fine now... But we have been having really bad oak moths--similar story--warm weather, stressed tress, happy caterpillars eating all the leaves...

Plus wild fires too. It's been smokey here every day for a month. The good news is that all the smoke should cool the Arctic and slow the melting of the ice caps.
<http://in.news.yahoo.com/139/20080723/981/tsc-distant-wildfires-has-the-net-effect.html>

asking - I got to thinking (dangerous, I know) about the plants, oxygen, Gaia... it occurred to me that while the cyanobacteria started the oxy process, plants would have already had to have been established on land to increase the oxygen enough for insects and other land critters to develop. So I guess I stand by my orig statement. (Tho I should have included the bacteria).

asking - I got to thinking (dangerous, I know) about the plants, oxygen, Gaia... it occurred to me that while the cyanobacteria started the oxy process, plants would have already had to have been established on land to increase the oxygen enough for insects and other land critters to develop. So I guess I stand by my orig statement. (Tho I should have included the bacteria).

I realize I don't know enough about this to reply. I've always read that cyanobacteria oxygenated the atmosphere and lead to iron oxides that are measurable in the geologic record. But I read a little about this recently and saw that there's controversy about how long after the first photosynthesing bacteria appeared the atmosphere became significantly oxygenated. This is measured by looking at pyrites, which react to UV irradiation. I guess (if I remember right) the oxygen reduced UV a lot, changing pyrite chemistry.

Anyway, to address your point more directly, how much is needed for insects to evolve? I don't know. Insects evolved with flowering plants, but I'm assuming that there were lots of both insects and non flowering plants before the rise of the angiosperms.

It's a cool topic I'd love to know more about. So you may well be right. Fun to talk to you. :)

I don't know if I've ever read an estimate on the amount of Oxy needed for insects to evolve, just that the amount afects their size. You claim not too much about evo but you come up with points I'd not known (or long since forgot... senior moments, CRS and all <G>) It is nice discussing it w/o having to defend the science behind it.

It is nice (to not have to defend science)!

Here is some information I dug up.

This is from Nature and is accessible without a subscription.
The rise of atmospheric oxygen : Article : Nature (http://www.nature.com/nature/journal/v451/n7176/full/nature06587.html)


Two facts are known with certainty: Earth's earliest atmosphere was essentially devoid of oxygen; and today's atmosphere is composed of 21% oxygen. Most of the events that took place between these two time points are highly uncertain. By the end of the twentieth century, a battery of geological indicators suggested a shift from an anoxic to an oxic atmosphere some time between 2.5 and 2.0 billion years ago. This shift is known as the great oxidation event.. .

The 'smoking gun' for the rise of atmospheric oxygen was discovered and reported in 2000 (ref. 4). Rocks older than about 2.45 billion years contain a large degree of mass-independent fractionation (MIF) of sulphur isotopes; rocks younger than 2.32 billion years show essentially none.

So atmospheric oxygen permanently went up about 2.45 billion years ago, although there was a "whiff" of oxygen 50 million years earlier. Why oxygen went up is still unknown, says the author. One theory is that fewer volcanoes were under water and more were on land, which changed geochemistry. (discussed here: Volcanoes Key To Earth's Oxygen Atmosphere (http://www.sciencedaily.com/releases/2007/08/070829143713.htm))


Or did cyanobacteria simply evolve oxygenic photosynthesis at this time, perhaps in response to some new selective pressure arising from the stabilization of continents?

BUT he seems to maybe dismiss this idea... He says oxygen was being produced 'at prodigious rates" before 2.5 billion years ago (by photosynthesizing bacteria) but was consumed faster than it was produced. Then something changed...But what?

There is also a review article in Science (last year) about oxygen and evolution, but it doesn't address what may have caused oxygen levels to rise or fall.

Science 27 April 2007:
Vol. 316. no. 5824, pp. 557 - 558
PERSPECTIVES
EVOLUTION:
Oxygen and Evolution
Robert A. Berner, John M. VandenBrooks, Peter D. Ward*

Basically, the authors say raising various animals with extra oxygen often leads to bigger size and raising them with less leads to smaller size. For example, trout raised at 38% atmospheric oxygen grew to be bigger than trout raised at the normal rate of 21%. The paleo record shows a correlation between more oxygen and increases in body size in several groups of animals. Oxygen declines were also correlated with some mass extinctions in the past "superimposed on global warming from increased greenhouse gas concentrations."

For example, rising oxygen levels coincided with the Cambrian explosion (the formation of all the major animal body plans ~530 mya); the colonization of land by spiders, insects, and other arthropods (410 mya); the appearance of giant insects and other arthropods as well as giant reptile-like animals (in the Carboniferous and Permian); and big mammals (in the Tertiary). Falling oxygen levels correlate with mass extinctions "superimposed on global warming from increased greenhouse gas concentrations."

Cheers

OK... now you've really got me interested and I'll have to do some research too. Nice to chat w/someone who actually looks things up...

BTW - I've noticed you and many here cite Wikpedia. While I like the idea of the resource, some things have a tendency to be polluted w/ non-fact. An example I read was on evolution where the info kept changing because ID folks started changing stuff. So while I'm probably missing out on a resource, I've never visited the site due to supposed unreliability. Have you found this to be the case?

I was looking up panspermia and on one site was a good amt of info. While I didn't quite agree with their critique of Darwinism (and evo theory in general) the Gaia section had a lot of links/credits for the subject we've been discussing. Source link:
COSMIC ANCESTRY: The modern version of panspermia. by Brig Klyce (http://www.panspermia.org/)

The following was just the first several of the oxic theories (I left out 2 dif ones f/ Nature):

Low oxygen and molybdenum in ancient oceans delayed evolution of life by 2 billion years
Low oxygen and molybdenum in ancient oceans delayed evolution of life by 2 billion years (http://www.eurekalert.org/pub_releases/2008-03/uoc--loa032408.php)
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Two Oxygenation Events In Ancient Oceans Sparked Spread Of Complex Life
ScienceDaily (Feb. 26, 2008)
Two Oxygenation Events In Ancient Oceans Sparked Spread Of Complex Life (http://www.sciencedaily.com/releases/2008/02/080225213645.htm)
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Origin of "Breathable" Atmosphere on Earth Found
"The study suggests that upheavals in the earth's crust initiated a kind of reverse-greenhouse effect 500 million years ago that cooled the world's oceans, spawned giant plankton blooms, and sent a burst of oxygen into the atmosphere.
That oxygen may have helped trigger one of the largest growths of biodiversity in Earth's history"
Newswise Science News | Origin of "Breathable" Atmosphere on Earth Found (http://www.newswise.com/articles/view/534742/)
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John W. Grula, "Evolution of Photosynthesis and Biospheric Oxygenation Contingent Upon Nitrogen Fixation?" [abstract <[astro-ph/0605310] Evolution of Photosynthesis and Biospheric Oxygenation Contingent Upon Nitrogen Fixation? (http://arxiv.org/abs/astro-ph/0605310)>], 10.1017/S1473550405002776, p 251-257 v 4 (3&4), International Journal of Astrobiology, Oct 2005.
"It is hypothesized that biospheric oxygenation would not have occurred if the emergence of cyanobacteria had not been preceded by the evolution of nitrogen fixation, and if these organisms had not also acquired the ability to fix nitrogen at the beginning of or very early in their history. The evolution of nitrogen fixation also appears to have been a precondition for the evolution of (bacterio)chlorophyll-based photosynthesis. Given that some form of chlorophyll is obligatory for true photosynthesis, and its light absorption and chemical properties make it a "universal pigment," it may be predicted that the evolution of nitrogen fixation and photosynthesis are also closely linked on other Earth- like planets."
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Now I have to find the time to read more of these than the 1st few paragraphs... <G>

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BTW - I've noticed you and many here cite Wikpedia. While I like the idea of the resource, some things have a tendency to be polluted w/ non-fact. An example I read was on evolution where the info kept changing because ID folks started changing stuff. So while I'm probably missing out on a resource, I've never visited the site due to supposed unreliability. Have you found this to be the case?

It depends on the topic. Anything controversial (like evolution, abortion, our president) is difficult because of vandals. Wikipedia has become stricter about locking down entries that are being vandalized. But even with the lock, something like evolution is going to be hard to maintain. It's not just accuracy, but also clarity that gets lost--too many cooks fighting over individual words.

On the other hand, a backwater topic (which most science is to the kind of people who vandalize wikipedia) is often pretty good. You can tell a lot about the reliability of an entry by the quality of the writing, how well referenced things are, and the sources cited for the information. Nature (the science journal) did a study a couple of years back that concluded that, for science, Wikipedia was nearly as accurate as the Encyclopedia Britannica.

Slashdot | Wikipedia's Accuracy Compared to Britannica (http://science.slashdot.org/science/05/12/15/1352207.shtml?tid=95&tid=14)

I don't have access to the original Nature article.

I use Wikipedia a lot. I also contribute to it. I've never written an entry, but I have corrected many, many small mistakes and added citations and paragraphs of information. The other weakness of Wikipedia is that entries about companies are often flack written by someone representing the company. That's not supposed to happen and entries that are too obvious are taken down, but often the bias is subtle.

Anyway, for things like paleoclimatology, I feel like I'm on pretty safe ground, especially if I check the references and they look reasonable.

Beware of articles written by undergrads as assignments. I found a whole collection of science biography pieces written by students from a single class at Princeton, most of which were badly written and full of errors. I was kind of shocked...

Lastly, often you can get a good sense of what has gone into a Wiki article by skimming the discussion page. If there's nothing there, the article was probably written by one person with little correction. If there are thousands of words of discussion and thousands more corrections (you can see every change that was ever made to every single article), then you are looking at something that was either labored over lovingly or fought over tooth and claw. Pretty easy to see which is which!

I like the Appalachian proverb. :)
And also the bit about nitrogen fixation. I hadn't thought about that. Makes sense.

And this gives an amount for animals generally, so 2-4% oxygen, they think.


For animal life to commence, survive and eventually expand on Earth, a threshold amount of oxygen – estimated to be on the order of 1 to 10 percent of present atmospheric levels of oxygen – was needed.

I feel the same about the panspermia website. There is some interesting material there, but I would definitely take it with a grain of salt, given his agenda to disprove evolution.

For example, here's a blogger complaining about it:
<http://complexityblog.com/nucleus/index.php?itemid=75>

Off to bed now. I wonder if there's a timeline of earth's history somewhere that shows temperature, atmospheric composition, arrangement of continents and what organisms were living. Would be useful.

Paleoclimatology - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Paleoclimatology)

Someone on another thread had inquired about this(plate tectonic history),I wish I had found it then.
global history (http://jan.ucc.nau.edu/~rcb7/global_history.html)

firmbeliever - glad to know you're still checking in on your question <G>

asking - thanks for the info on Wik. Guess I will visit after all. But I'm going to have to wait for another day to check out more oxcic on the panspermia site... Way past time f/ this ole gal to hit the hay.

Firmbeliever, These are great!

But I admit I want it all combined into one easy to read graphic and include all the kinds of life that lived at each time. Maybe I'll try to make something myself. :)

Asking,
How about these ones?. I don't understand most of it,but I think you can easily understand the timeline.
Geological Timeline (http://www.totallydifferent.co.uk/acatalog/Geological_Timeline.html)
Geological and evolutionary timelines (http://earthsci.org/fossils/geotime/time/geotime2.htm)
Geologic and Biological Timeline of the Earth (http://www.scientificpsychic.com/etc/timeline/timeline.html)