[firmbeliever]

Asking,
Thank you for the explanations.

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

[firmbeliever]

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

[WVHiflyer]

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.


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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.


_

[WVHiflyer]

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

[asking]

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

[firmbeliever]

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.

[asking]

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

[firmbeliever]

Thank you asking.

Here is an example of what I mean.
How the Pine Beetle is Destroying Colorado Forests | Newsweek Project Green | Newsweek.com

[WVHiflyer]

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>).

[WVHiflyer]

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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[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

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>

[WVHiflyer]

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]

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. :)

[WVHiflyer]

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.

[asking]

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

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)

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

[WVHiflyer]

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?

[WVHiflyer]

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

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
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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
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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
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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?>], 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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[asking]

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

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!

[asking]

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.

[firmbeliever]

Paleoclimatology - Wikipedia, the free encyclopedia

Someone on another thread had inquired about this(plate tectonic history),I wish I had found it then.
global history