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thaphantum

How Exactly Do They Date Fossils?

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joc

I dated a fossil once...once!

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leadbelly
Evolutionary Hoaxes, Scams, and Abuses

6. Lucy (Ramapithecus) - once widely accepted as the direct ancestor of humans, it has now been realised that this skeleton is merely an extinct type of orangutan - not an early human.

Can someone cite such an assertion, from an accredited scholarly source? I have never read any "creationism", but if this is so much smokescreen for lack of evidence, it does little justice for real knowledge.

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magnetar

In 1973, Donald Johanson was in the Afar, part of the Hadar region of Ethiopia, with the International Afar Research Expedition. He made a dramatic fossil find -- the leg bones of 3-million-year-old hominid. The bones' size and shape indicated that this individual walked upright, making it the oldest hominid on record to do so. This discovery helped Johanson raise enough money to continue the expedition in the Afar.

On November 30, 1974, Johanson and another member of the expedition discovered small bones from one individual -- it was a hominid, but looked different from any they were familiar with. Everyone at the site joined in the search for more of this specimen and collected hundreds of pieces. The pieces did appear to be from the same individual, and made up 40 percent of a skeleton. The pelvis showed it had been a female, and the team named her Lucy after the Beatles' song "Lucy in the Sky with Diamonds."

Lucy had a small brain and was only about one meter tall. Since bones from both left and right sides were found, mirror images could be constructed to put together 70 percent of her skeleton. More than one dating technique put her age at about 3.5 million years. (Johanson's earlier leg bone find was dated at 4 million years old.) The team kept working at the site and found other, more modern hominids together with stone tools. By 1976, however, Ethiopia's political situation was unstable, making further excavations unsafe or impossible.

In 1978, Mary Leakey discovered ancient footprints preserved in the ground around what was once a water hole at Laetoli, Tanzania. These prints showed clearly that small primates walked on two feet there. This put upright walking even further back in time.

Johanson and his colleague Tim White compared Leakey's finds at Laetoli with theirs from Afar, and felt that they were very similar, probably representing a stage between apes and humans. They categorized them both as Australopithecus afarensis. Leakey disagreed, but both of their finds broke a long-standing assumption: that humans developed big brains before walking upright. After 1974, scientists realized that this wasn't necessarily true, and that brain size overlaps between types of hominids, even as modern people's brains vary in size without relation to intelligence. This meant they had to look again at why hominids started walking upright. It had been thought that the big-brained creatures started using tools, and to free up their hands, they had to walk upright. But Lucy walked on two feet, and even had "modern" hands, yet showed no evidence of using tools.

Opponents of Johanson and White's theory think the Homo genus had a separate lineage from other primates. Johanson acknowledged that his explanation would be subject to change with new evidence.

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Edited by magnetar

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magnetar

Australopithecus afarensis existed between 3.9 and 3.0 million years ago. Afarensis had an apelike face with a low forehead, a bony ridge over the eyes, a flat nose, and no chin. They had protruding jaws with large back teeth. Cranial capacity varied from about 375 to 550 cc. The skull is similar to that of a chimpanzee, except for the more humanlike teeth. The canine teeth are much smaller than those of modern apes, but larger and more pointed than those of humans, and shape of the jaw is between the rectangular shape of apes and the parabolic shape of humans. However their pelvis and leg bones far more closely resemble those of modern man, and leave no doubt that they were bipedal (although adapted to walking rather than running (Leakey 1994)). Their bones show that they were physically very strong. Females were substantially smaller than males, a condition known as sexual dimorphism. Height varied between about 107 cm (3'6") and 152 cm (5'0"). The finger and toe bones are curved and proportionally longer than in humans, but the hands are similar to humans in most other details (Johanson and Edey 1981). Most scientists consider this evidence that afarensis was still partially adapted to climbing in trees, others consider it evolutionary baggage.

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magnetar

Despite her lack of formal education, Mary Leakey stands out as one of the premiere archaeologists--let alone female archaeologists--of this century. Although Mary's research is often talked about in conjunction with that of her archaeologist husband and sons, her major finds are more than enough to gain her personal acknowledgment.

Mary first visited Laetoli, an area 30 miles south of Olduvai, in 1935 but didn't establish a permanent site there until 1974. In July of 1975, the first serious excavations began. Early digs revealed an abundance of hominid materials which were dated (by finding the age of overlying lava flows) at more than 2.4-million-years-old, placing them much earlier in time than any found at Olduvai. An even more exciting find occurred in 1976 when visitors to the site accidentally stumbled upon what seemed like fossilized animal prints. "Site A," as it came to be called, ended up containing almost 18,400 individual prints. Then, in 1978, two short parallel trails of hominid prints were found by a man named Paul Abell, again by accident. Eventually, these trails were found to extend more than 80 ft in rock that was dated at 3.6-million-years-old. The prints were made by two individuals walking side-by-side, with a third deliberately stepping in the footprints of the largest individual; Mary liked to believe that they were of the genus Homo, but other scientists, including Donald Johanson (of "Lucy" fame) think they might be of the Australopithecus line. (In fact, this was a big point of contention in a vicious feud between Leakey and Johanson.)

Despite all of the questions that the footprints raised, and that remain unanswered even today, Mary deemed their discovery as one of the most important made in her lifetime. For instance, the absence of stone tools at the site leads scientists to believe that bipedalism preceded the use of tools. Mary later explained, "The discovery of the trails was immensely exciting-something so extraordinary that I could hardly take it in or comprehend its implications for some while." After their excavation, Mary finished her stay at Laetoli, ending also the most memorable stage of her archaeological career.

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magnetar

Lee R. Berger

for National Geographic News

Viewpoint: Is It Time to Revise the System of Scientific Naming?

A team of researchers led by paleoanthropologist Meave Leakey sparked a controversy among evolutionary scientists and the press alike earlier this year when they announced the discovery of a new genus and species of ape-man.

They named their find Kenyanthropus platyops, the "flat-faced man of Kenya." Ordinarily, the find itself would be enough to spark a flame of controversy in the heart of any follower of human origins research. But this find also highlighted an ongoing debate within the scientific community over the adoption of a new system for naming, ranking, and classifying organisms.

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magnetar

National Geographic-

Unlike Lucy, here is a baby, who has fingers, a foot, and a complete torso. But, the most impressive difference between them, is that this child has a face.

Australopithecus aferensis-

post-22777-1176905870_thumb.jpg

post-22777-1176905919_thumb.jpg

post-22777-1176905954_thumb.jpg

post-22777-1176906002_thumb.jpg

post-22777-1176906033_thumb.jpg

post-22777-1176906066_thumb.jpg

Edited by magnetar

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Fearisgood
Can someone cite such an assertion, from an accredited scholarly source? I have never read any "creationism", but if this is so much smokescreen for lack of evidence, it does little justice for real knowledge.

Here is quite a new reference for you.

Published online before print April 10, 2007

Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0606454104

Yoel Rak *, Avishag Ginzburg *, and Eli Geffen

*Department of Anatomy and Anthropology, Sackler Faculty of Medicine, and Department of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel

Edited by David Pilbeam, Harvard University, Cambridge, MA, and approved February 26, 2007 (received for review July 28, 2006)

Mandibular ramus morphology on a recently discovered specimen of Australopithecus afarensis closely matches that of gorillas. This finding was unexpected given that chimpanzees are the closest living relatives of humans. Because modern humans, chimpanzees, orangutans, and many other primates share a ramal morphology that differs from that of gorillas, the gorilla anatomy must represent a unique condition, and its appearance in fossil hominins must represent an independently derived morphology. This particular morphology appears also in Australopithecus robustus. The presence of the morphology in both the latter and Au. afarensis and its absence in modern humans cast doubt on the role of Au. afarensis as a modern human ancestor. The ramal anatomy of the earlier Ardipithecus ramidus is virtually that of a chimpanzee, corroborating the proposed phylogenetic scenario.

http://www.pnas.org/cgi/content/abstract/0606454104v1

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leadbelly

Thank you.

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Essan
2. Neanderthal Man (Homo sapiens neanderthalensis) - 1856, in Neanderthal, Germany, a skull cap and limb bones were found. It was grouped with a set of skeletons found all over Europe that had the following characteristics: prominent eyebrow ridges, low forehead, long narrow brain case, protruding upper jaw, a strong lower jaw lacking a chin. The overall skeletons were short, and stooped-over. Anthropologists believed it to be a “missing link” between man and ape because it seemed to have shuffled along when walking. However, 150 years later, it is now admitted that these skeletons were of people that suffered from rickets, and syphilis. Neanderthal Man was just a variation of the modern human kind with disease!

Utter codswallop!

The only question about Neaderthalensis is whether or not there was any interbreeding between them and ourselves. They were a variation of homo sapien sapien in the same way that a Poodle is a variation of a Wolf ....

The problem with creationists is that they make no effort to understand evolution - it's a bit like someone saying that the TV news can't be real because they looked inside the TV set and there was no-one there.

btw guess how many missing links there are? Millions! Each generation is the link from the one before to the one after. Each generation is very, very, very, very, very subtlely different. If one takes a member of every thousandth or 10 thousandth generation one actually notices these differences, but there is no one generation in which the change actually takes place. Comparing specimens a million generations apart one might well determine that one is looking at completely different species. But when exactly did the one species 'turn' into the other? ;)

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bloke

[qoute]

btw guess how many missing links there are? Millions! Each generation is the link from the one before to the one after. Each generation is very, very, very, very, very subtlely different. If one takes a member of every thousandth or 10 thousandth generation one actually notices these differences, but there is no one generation in which the change actually takes place. Comparing specimens a million generations apart one might well determine that one is looking at completely different species. But when exactly did the one species 'turn' into the other? <img src="http://www.unexplained-mysteries.com/forum/public/style_emoticons/<#EMO_DIR#>/wink2.gif" style="vertical-align:middle" emoid=";)" border="0" alt="wink2.gif" />

Mmm, Go out an buy yourself a fossil book, any will do. You see what the fossil record (and any fossil book) will show you is that fossils are not smoothly graded as you describe - they disagree with the theory. They all stick to their type (read species if you like). You get some variation but a trilobite is a trilobite and an ammonite is an ammonite.

I'm sure that if there was any evidence for the small step change that is essential for evolution (Dawkins - the Blind Watchmaker is very clear about the required small steps) it would be clearly illustrated by numerous graded examples in your book on fossil identification. But that data is missing and you won't find it in your book. And while we're on the subject of small steps - how does the first living organism appear? - and I mean anywhere in the universe - not in a relatively small space of time on a hostile early earth.

Statistically if all the atoms in the universe spend every second of the universes 14 billion years attempting to make a simple single minimal 250 amino acid functional protein chain, there are simply not enough atoms or enough time. minimal life requires hundreds of proteins, a working reproductive system based on DNA and protein replication machinary and that's got to come together as a working whole BEFORE reproduction - so you CANNOT invoke evolution and natural selection. (Chemical evolution is just desperate speculation).

What you quote is the theory - the idea. However the evidence is missing - wholesale!

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Copasetic

btw guess how many missing links there are? Millions! Each generation is the link from the one before to the one after. Each generation is very, very, very, very, very subtlely different. If one takes a member of every thousandth or 10 thousandth generation one actually notices these differences, but there is no one generation in which the change actually takes place. Comparing specimens a million generations apart one might well determine that one is looking at completely different species. But when exactly did the one species 'turn' into the other? <img src="http://www.unexplained-mysteries.com/forum/public/style_emoticons/<#EMO_DIR#>/wink2.gif" style="vertical-align:middle" emoid=";)" border="0" alt="wink2.gif" />

Mmm, Go out an buy yourself a fossil book, any will do. You see what the fossil record (and any fossil book) will show you is that fossils are not smoothly graded as you describe - they disagree with the theory. They all stick to their type (read species if you like). You get some variation but a trilobite is a trilobite and an ammonite is an ammonite.

Well first off welcome to the forum. Also, I'd like to add that there are some very knowledgeable members here, so be careful casting stones (You know what they say about that right? ^_^ ) On to your post!

Of course fossils aren't 'smoothly graded', because fossilization is rare. However Bloke, you'd notice (had you spent a little more time digesting Essans post) that he was talking about life. Not fossils. And he is right, because of a few inescapable facts of nature. Firstly that all organisms bequeath similar organisms. Secondly, that allele frequencies change from generation to generation.

The consequence of this is there would no single where we could divide one 'species' into the next.

Of course a trilobite is a trilobite and an ammonite is an ammonite. Why should they be anything but those things? Again, only with the luck of hindsight and the incompleteness of the fossil record does assigning organisms to discrete groups have any meaning at all (and if you understand evolution, you understand how petty these groups are).

Like Essan pointed out, this graded change through generations is only noticeable with the lucky fact that fossilization is rare. Where we, for every extant lineage, to have a fossil representative of every ancestor from every generation then grouping into species would be impossible. Because, the record would only show organisms giving birth to similar organisms and only over geological time would marked differences (what me might call 'macro-evolution', though there is no such distinction) be noticeable.

I'm sure that if there was any evidence for the small step change that is essential for evolution (Dawkins - the Blind Watchmaker is very clear about the required small steps) it would be clearly illustrated by numerous graded examples in your book on fossil identification. But that data is missing and you won't find it in your book.

Of course there is 'small step' changes and many thousands, probably millions, of examples of them.

Consider where E. coli evolved a new metabolic pathway to digest citrate (read new 'information' evolving)

Or consider humans evolving the ability to digest lactose.

Or consider these examples of recent selection on mutations (new variation) in humans.

And while we're on the subject of small steps - how does the first living organism appear? - and I mean anywhere in the universe - not in a relatively small space of time on a hostile early earth.

Well that depends Bloke on how you define organism. Remember that 'life', 'organism', 'living', etc, are human defined and imposed terms. That is to say, they aren't real rules of nature, rather our habitual need to cram things in definable boxes.

Consider what I mean by this, by reading this post to another poster I made not long ago;

Okay, going back to this: "no mater how you believe it started nuthing alive is etearnal." What I wanted to talk about (besides for the word 'nuthing' there) is what it means to be alive-Obviously you consider this an important point.

I am going to work on the assumption that you accept my definition for life, as I don't foresee you providing any kind of empirical definition of life. Recall that definition was;

So the point in this is, how then do we place a virus in this sense? For a virus is not capable of 1,2,3,4(ish). Obviously a virus then, isn't alive. Yet at the same time we can make a strong logical and testable argument that while a virus may not be alive, it certainly has some life like properties.

Now consider something more simple; a prion. Famous for causing bovine spongiform encephalopathy (mad cow disease), CJD in humans and Kuru in humans-To name but a few famous examples. A prion is an infectious form of protein-A protein made and manufactured in good ol' you. In fact, the same protein is found throughout the class of animals we call mammalia. Proteins you see, can be folded in many different 'forms', which are determined by weak bonding throughout the molecule. In one form, this protein is deadly and accumulates in the brain. It replicates itself by inducing other proteins of the same type to 'fold incorrectly' (incorrectly for your brain, great for the protein).

So here again we have a conundrum, something life like yet not alive....Hmmmmmm....Hmmmmmmmm :blink:

Let's walk a bit toward the other end of the spectrum (from viruses that is). Mycobacterium leprae, or the causative agent of leprosy. Even with all our sophisticated lab techniques, we are unable to grow pure cultures of M. leprae. Why? Because this organism is what we call an obligate intracellular pathogen. With a genome with only 1600 some genes, it no longer can survive on its own accord and similar to the virus, must use another cell to replicate self.

So going back to our criterion for life, we meet numbers 1, 3, and 5. Obviously Mycobacterium aren't alive! Yet they are capable of evolving, speciating and being one of the leading causes of human mortality throughout history. In fact one little member of this genus (Mycobacterium tuberculosis) is responsible for more deaths in the developing world (modern day too mind you) than HIV/AIDs, diphtheria (diarrhea) and malaria combined. All from an organism, that isn't really living.

Going a little further along our shades of gray we meet organisms like Mixotricha paradoxa-A not so special, special protists which lives in the hind gut of termites. When first viewed under the microscope it appeared they, like many other ciliated protists, had cilia.

Mixotrichaparadoxa.jpg

Later it was discovered that the 'cilia' were not actually cilia, rather bacteria. A very cool type of bacteria called spirochetes. This particular 'type' of spirochete is found only living embedded in the Mixotricha.

mix05.jpg

So if these bacteria, only exist embedded in the Mixotricha, how can they be free living organisms? How can they be considered alive? Or maybe an even more important boundary we are blurring here is what is 'self'

Even amongst your own cells, you are intimately intertwined with something 'not you'. Oxygen is an essential part of life, yet your cells in your body have no idea what to do with oxygen. Instead they rely upon a discovery hit upon by a clade of bacteria two billion years ago. I am of course talking about your mitochondria and their ancestors which they share with the Rickettsias.

To your mitochondria they are still a population of bacteria confined to an environment (your cell), who carry on their bacterial business. They go about their lives dividing and replicating, just as do their modern, free-living counterparts. With their own genomes (not yours) and their own, discrete cells. Every now and again, their population experiences a traumatic event as your cell and their population is ripped into two.

Are you starting to see it now Kbeet? Life, it turns out, doesn't much care for how we humans wish to define it or wish it to behave. It is indeed a complex sea of gray areas. The very notion that something is either 'living' or 'not' is silly. This tendency arises from the dualist absolutist brain of man-That something so vastly complex and beautiful as life could be neatly defined.

Again to steal a concept from Dick Dawkins ( ^_^ ): No body believes people are either grown-ups or children, similarly no one believes that on the stoke of midnight on your 18th birthday you cease to become a child and are an adult. The whole process of growing up is melded shades of gray. For the sake of the law, we need clearly defined absolute values to place upon a definition which we can discriminate child from adult. But, in real life there exists no such point when a child becomes and adult-As much as some children (and possibly adults) would like to believe.

Getting it now Kbeet?

This whole concept of 'shades of gray' and our over tendency to enforce a finite definition is not only done to life-But the very essence of life-The organism.

We are existentialists, we must be to grow and develop in the societies we occupy. Unfortunately we try to carry this over to the sciences as well. We do the same thing to organisms when we declare "who was the first blah blah blah of the species".

I'd like for you to now consider another example I have been using on these forms for a few years now.

(Read on Guyver, I think you'll appreciate this as well)

I'd like you to meet the salamander Ensatina.

klaub73.gif

These little guys live in the lovely land of California (yes I picked this cause all of you Californians reading along!)

Their populations make a ring around the San Joaquin Valley, the middle far to desolate for all but the rarest of circumstantial crossings to occur.

What we find is populations next to each other on the ring, are able to interbreed with one another-Clearly they are of the same species. However, when we get farther apart, interbreed cannot occur. The populations at the end of the ring, are also unable to interbreed with each other.

Here, see it visually;

Ensatina_rassenkreis_3.gif

ensatina.gif

So we have interbreeding all the way around the ring, yet when we get to the red and green in the second picture-We have none. Similarly if you put yellow and pink or red and orange (second picture again) together-We have none.

So where pray tell does one start and the next stop? Or better which is the first of 'male and female' of one and not the next.

That alone should shatter the warm, gooey existentialist tendency you have to lump groups of organisms as species.

And here is the real crazy part!

These salamanders do spatially, what occurs temporally in evolution. That is correct. There is no first person or first two people, because all progeny of their parents are the same 'kind' as their parents and only when looking at the statistical cloud of genes we call a gene pool, over eons, do we see 'finite' bounds to species-Because the 'paradox' created by evolution over time. That same paradox I was referring to above with Sheri and Guyver.

Do you see now?

If still not yet then I'd like to leave you with more tidbit, rather an experiment;

Put all that in your beer and drink it ^_^ , no but really read that over a few times Kbeet. Let the profound implications absorb.

Link

Statistically if all the atoms in the universe spend every second of the universes 14 billion years attempting to make a simple single minimal 250 amino acid functional protein chain, there are simply not enough atoms or enough time. minimal life requires hundreds of proteins, a working reproductive system based on DNA and protein replication machinary and that's got to come together as a working whole BEFORE reproduction - so you CANNOT invoke evolution and natural selection. (Chemical evolution is just desperate speculation).

Actually bloke, you have confused the requirements of modern life with early life (again, life is a flexible definition, not a law of nature)

I've yet to hear any biologists postulating about proteins forms and complex molecular machinery forming on its own--Indeed, that version of abiogenesis is the creationists version (and paradoxically, the version they are most obsessed with disproving to each other).

Currently we don't know how life started, but there is certainly some good ideas. For instance, ribonucleosides readily polymerize in the presence of UV light. If such polymerization took place so as to sequester and compete for nucleosides (a limitation of resources) then you have a replicating system where competition leads to selection (some chains are more stable via others). That is of course an example and hypothetical, as I stated above, we don't know yet how life started. That certainly doesn't invalidate evolutionary theory (the theory that explains the biological fact of evolution, which deals with how life changes over time) nor does it mean a supernatural agency needed to intervene. If your of mind to insert your god of the gaps into this current gap in knowledge, than that can certainly be your prerogative; however, with the exponential speed that science erases gods-of-gaps, I certainly wouldn't gamble any money on it. :tu:

Edited by Copasetic

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Thinkicon

Interesting thread/post

Radiometric dating is based on measuring quantities of certain isotopes and comparing it to....the original amount? Isn't that a presumption, on a grand scale. How can they be sure that the daughter isotopes were not present at the time they define as their starting point? Would that not throw off the measurement?

Someone mentioned there is no lead in magma. Is lead only found because of radioactive decay?

Read an article on dating fossils "How do scientists determine the age of dinosaur bones?" http://science.howstuffworks.com/environmental/earth/geology/dinosaur-bone-age.htm

Not a bad article if the author had originally started simply with the opening statement: This is how its done. However, the initial premise was that flesh, which was found with the bones, is not supposed to exist after 68 million years. There is no explanation. So either some process allows for the flesh to remain OR the dating process is flawed.

Wrt to last post on "life". Ok, what does define life? How did that very first form of life begin? IF we evolved, it had to start somewhere. It was stated that "ribonucleosides readily polymerize in the presence of UV light". If true, first it requires a ribonucleoside to exist. Its not a simple molecule.

If it was a creationist that first hypothesized abiogenesis, I could see it because "I've yet to hear any biologists postulating about proteins forms and complex molecular machinery forming on its own". Doesn't it stand to "reason" that life has to begin some where, some how? Perhaps these "biologists" just don't want to go there. Its a lot easier to argue evolution from the present than it is to postulate about its beginnings.

All the very simple forms of life described above rely on other "life" (more complex life) to survive, symbiotic or parasitic, which in itself is a highly complex adaptation.

I always thought abiogenesis was part of the theory as I was taught at univ, ie the pool of goo, spark, and life starts. That biologists don't postulate about it is not a surprise. It seems more like the Achilles heel to whole theory.

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J. K.

Of course fossils aren't 'smoothly graded', because fossilization is rare. However Bloke, you'd notice (had you spent a little more time digesting Essans post) that he was talking about life. Not fossils. And he is right, because of a few inescapable facts of nature. Firstly that all organisms bequeath similar organisms. Secondly, that allele frequencies change from generation to generation.

The consequence of this is there would no single where we could divide one 'species' into the next.

Hey, copa

I think that is one of the issues that throws people off, along with the idea that classifications are human labels as opposed to nature's labels. I understand what you mean by "no species division." However, please realize that those divisions are often publicized in that manner -- "We found a partial skeleton! It's an Australopithecus afarensis!" -- so it's only natural for us to use such terms in discussion.

Please understand that the difficulty for persons like me is partially the staggering number of allele changes that would have to occur between, for example, Maelestes gobiensis and my house cat. I am aware that it was not an overnight change, and that we had previously discussed re-usage of existing features. However, part of what I don't understand is this (unless what I'm referencing an urban legend): for M. gobiensis to evolve to a house cat would require many, many changes over 75 million years. How is it that over that same time period, some animals experienced very little change other than size? (Alligator, tortoise.)

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Robbie333

i figured i'd do some digging into how fossils are dated... so i pulled up some info...

Carbon 14 Dating...

"Because the half-life of carbon-14 is 5,700 years, it is only reliable for dating objects up to about 60,000 years old. However, the principle of carbon-14 dating applies to other isotopes as well."

source: http://www.howstuffworks.com/carbon-142.htm

source2: http://www.museum.vic.gov.au/prehistoric/what/fossilage.html (states a max dating of 70,000 years)

once i saw that it was only accurate up to 60,000 years... i figured i'd have a look at the rest...

carbon 14 - Fossil wood, shell, bone, fabric and ash between 1000 and 70000 years old.

uranium 235 - Uranium ores and granite rocks more than 110000 years old.

potassium 40 - bearing minerals more than 100000 years old

uranium 238 -Uranium ores and granitic rocks more than 10 million years old.

thorium 232 - Uranium ores and granitic rocks more than 50 million years old.

rubidium 87 - Some granitic rocks, sandstones, igneous, sedimentary and metamorphic rocks more than 10 million years old.

source: http://www.museum.vic.gov.au/prehistoric/what/fossilage.html

ok... so at this point... i notice there aren't any other means of testing bone, wood, fabric, and ash... all the rest are used to test some form of rock...

so someone explain to me exactly how they test the fossils?

so i figured i'd check out fossil dating... and from what i understand... they don't actually test the fossil... they date it according to how far down it's buried and what rocks are near it...

"The oldest method is stratigraphy, studying how deeply a fossil is buried. Dinosaur fossils are usually found in sedimentary rock. Sedimentary rock layers (strata) are formed episodically as earth is deposited horizontally over time. Newer layers are formed on top of older layers, pressurizing them into rocks. Paleontologists can estimate the amount of time that has passed since the stratum containing the fossil was formed. Generally, deeper rocks and fossils are older than those found above them.

Observations of the fluctuations of the Earth's magnetic field, which leaves different magnetic fields in rocks from different geological eras.

Dating a fossil in terms of approximately how many years old it is can be possible using radioisotope-dating of igneous rocks found near the fossil. Unstable radioactive isotopes of elements, such as Uranium-235, decay at constant, known rates over time (its half-life, which is over 700 million years). An accurate estimate of the rock's age can be determined by examining the ratios of the remaining radioactive element and its daughters. For example, when lava cools, it has no lead content but it does contain some radioactive Uranium (U-235). Over time, the unstable radioactive Uranium decays into its daughter, Lead-207, at a constant, known rate (its half-life). By comparing the relative proportion of Uranium-235 and Lead-207, the age of the igneous rock can be determined. Potassium-40 (which decays to argon-40) is also used to date fossils. "

so after getting passed that... i get down to this...

"Radioisotope dating cannot be used directly on fossils since they don't contain the unstable radioactive isotopes used in the dating process. To determine a fossil's age, igneous layers (volcanic rock) beneath the fossil (predating the fossil) and above it (representing a time after the dinosaur's existence) are dated, resulting in a time-range for the dinosaur's life. Thus, dinosaurs are dated with respect to volcanic eruptions. "

source: http://www.enchantedlearning.com/subjects/...ssildating.html

bascially what i gather from this... it's just a long drawn out way of making a guess?

from what i figure... if tectonic plates shift... wouldn't it be possible for fossils to move further down in the earth? or if something collapsed on a person... and they are found 200 years from now... would they be dated at millions of years old?

how exactly is dating rocks an accurate way of testing the age of fossils?

isn't it possible that they could be wrong?

TrueThat said earlier that they found "soft tissue" in dinosaur bones... and maybe they should look closer at the how they date the age of dinos... instead of trying to figure out how "soft tissue" can survive as long as it has...

after further investigating the dating system... i really think they should take a closer look at the dating of fossils...

if it turns out their dating system is off...

1) how would it effect the theory of evolution?

2) would you still have faith in science if it turns out that the fossils were millions of years younger?

3) if the fossils were millions of years younger, would you still think evolution is correct?

At my age most of my dates are fossils---sorry.

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Copasetic

Let me preface this by saying you guys ought to pay attention to the post dates you are replying too. This is a couple of year old topic!

Interesting thread/post

Radiometric dating is based on measuring quantities of certain isotopes and comparing it to....the original amount? Isn't that a presumption, on a grand scale. How can they be sure that the daughter isotopes were not present at the time they define as their starting point? Would that not throw off the measurement?

Someone mentioned there is no lead in magma. Is lead only found because of radioactive decay?

To answer your last question first lead on earth comes in two flavors. Stable lead isotope that was formed via nucleosynthesis and lead that is the end products of radioactive decay.

As to how the "measurements" are figured out for radiometric dating, I've made a post explaining how that is calculated before, summarized now:

As Doug pointed out on the other topic, for one atom chances of decaying are random. When you have many, many atoms (like greater than or equal to Avagrado's number) then the decay follows a precise statistical pattern.

What we can do is derive the half-life and decay constant of the radioactive material then use that to date samples. Let's use tritium as an example. Let's say we wished to find the half-life of tritium so we can date a sample of it.

We can go into the lab to determine this using the formula (for logarithmic decay):

A=Aoe-kt

Where A, is the amount of sample at time, t, Ao is the initial amount of sample and k is the decay constant. (e is the base constant of the natural logarithm).

So let's say we had 1500 grams of tritium and monitored its mass loss over 1 year. After a year we find that 94.529% of its mass remains. First we need to determine tritium's universal decay constant, k.

We can say that A= .94529 Ao and we know this took place over time t= 1 year.

So substituting in our formula we get:

.94529Ao = Aoe-k*1 year

Notice the Ao cancel on each side;

.94529 = e-k*1 year

To solve for k, take the natural log of both sides:

ln (.94529) = ln (e-k*1 year)

Because of the properties of natural logarithms we can rewrite it as follows;

ln (.94529) = -k*1 year;

ln (.94529)/-1 year = k;

k = .0563 y-1

Now we know the rate constant of tritium, this is a constant and is the same for all tritium. It doesn't matter where or how big your samples are, if measured accurately it will always be the same. There are also other ways we can check this, but we won't go into that here.

Now, Let's figure out the half-life so we can date some imaginary samples.

The half life just means when one half of the sample has decayed. In other words we want to solve for t, when;

A=(1/2)Ao

Since we solved for our rate constant above, we can simply plug and chug with our observational numbers from the lab!

(1/2)Ao = Aoe-kt, (remember we solved for k above, but I am going to write k to save time for now)

Again our Ao's cancel out and we take the natural log of both sides to get;

ln (1/2) = ln e-kt

Again using the properties of logs we get;

ln (1/2) = -kt

Then solve for t

t= ln (1/2)/-k when k =.0563, and after plugging in the faithful calculator we get

t1/2 = 12.31 years.

(Quick side note, because we have rounded our k and t1/2 are slightly off real world data, the half life of tritium is actually closer to 12.32 and the decay constant is closer to .0565, but for a forum example its close enough, We're not building an Ark or anything! ;) ).

So that is how scientists come up with the half-life and decay constant, which are universally specific for a group of decaying atoms. But what can we do with it? How do we use this information to find an age?

How on Earth do scientists figure out the date of something if they don't know the initial amount Ao!

The answer is, reasoning and math! (damn you math!)

As we saw in the formula above for tritium's decay 1 daughter nucleus (3He2) is produced through the decay of 1 parent nucleus (3H) which gives us a 1 to 1 ratio and we can express this mathematically as well;

A + D =Ao

Where A is the amount of parent isotope we measured in a sample at some time t, D is the amount of daughter isotope we measured in the sample and Ao is the initial amount at t=0.

Thus we can rewrite our formula as follows;

A=Aoe-kt Substitute for Ao as we get;

A=(A+ D)e-kt Then solve the equation for time, t and we get

t= ln (A/(A+D)) /-k and which we can rewrite as;

t= (1/k)ln ((D/A) +1) So the term (D/A) that is the measured amount of daughter to parent negates having to know the initial amount of parent isotope.

So let's say we had some thing that contained tritium and we wanted to know how old it was. So we go into the lab and using some very cool equipment (something called mass spectrometer, which measures the relative concentrations of atoms in a sample) find that we have 7 grams of the daughter isotope, 3He2, and 2 grams of the parent isotope, 3H.

We just simply plug and chug with our formula from above;

t= (1/k)ln ((D/A) +1);

t= (1/.0563 years)ln ((7g/2g) +1);

t= 26.72 years old!

Original link

You might also find the following link useful Radiometric dating a Christian perspective.

Read an article on dating fossils "How do scientists determine the age of dinosaur bones?" http://science.howstuffworks.com/environmental/earth/geology/dinosaur-bone-age.htm

Not a bad article if the author had originally started simply with the opening statement: This is how its done. However, the initial premise was that flesh, which was found with the bones, is not supposed to exist after 68 million years. There is no explanation. So either some process allows for the flesh to remain OR the dating process is flawed.

Well it wasn't flesh, the bone was well sealed and not broken so the mineralization process that occurs during fossilization had limited access to the inside of the bone. Because of that, there was extracellular matrix in a somewhat "original" form. Note however, it wasn't like "new" out of the dinosaur and still needed multiple acid washes (hydrochloric acid) to make the "flesh", "flesh" again.

Wrt to last post on "life". Ok, what does define life?

Humans. There isn't a "natural phenomena" of life. The important thing to understand is that evolution, particularly evolution by natural selection does not require something be alive to act. For a modern example look at viruses. Viruses by our definition of life are non-living infectious particles. They still evolve by selection however.

How did that very first form of life begin? IF we evolved, it had to start somewhere. It was stated that "ribonucleosides readily polymerize in the presence of UV light". If true, first it requires a ribonucleoside to exist. Its not a simple molecule.

In deed it did have to start 'somewhere'. Its important to understand that in science theories (which explain facts and natural phenomena) are specific. Evolutionary theory (the modern synthesis) explains the biological fact of evolution (that from generation to generation allele frequencies change). That is all it can explain--A question of biodiversity. It cannot explain the origin of life. In science we have another explanation for that--Abiogenesis. At current we don't know how the first replicator came about (I say replicator here, because its important to understand the "first things" wouldn't have been cells--rather self-replicating molecules or systems of molecules).

The most supported (via evidence) at current is through RNA or ribonucleic acid, because RNA can function as an "information" carrier (ie; heredity) as well as being enzymatically functional. Your own cells utilize autocatalytic RNA in the form of rRNA (ribosomal RNA).

You're right however it does in deed require nucleic acids "exist" for this process to start. In deed there have been natural syntheses worked out for all the nucleic acids found in living organisms. In fact there is many "complex" organic molecules that arise through abiotic processes. How do we know this? Because we can look out in the universe and see them. This next post was addressing another question about chirality, but actually should give you an idea;

Hey Guyver,

Sorry it took me so long to get a reply up for you. The first thing I'd like to point out, is that the 'problem of chirality' isn't a problem for neo-Darwinism or the modern synthesis (modern evolutionary theory) to answer. That's like expecting atomic theory to answer why continents move.

To reiterate an often brought-up point, science is specific in its fields of study and what it's theories seek to answer. Scientific theory explains facts, giving us a better understanding of our world. But, those theories are only useful if they are narrow in scope.

The modern synthesis explains the fact of evolution and biodiversity of life on earth and can only explain those facts. The origin of life, or abiogenesis would be a separate fact which required separate theories and mechanisms to explain.

Do you understand that? Please respond that you do.

That all said, you've still asked a great question (just of the wrong crowd of scientists). I am not sure though, that this question is one so important as creationists (henceforth I'll use 'creation' and 'creationist' to refer to the entire spectrum of creationism, including ID) seem to imply.

To say that chirality is something which can only be designed into a system is false, as anyone who has taken an organic chemistry would know.

I think to really think about your question, we need to first consider what we know of nature's preference toward chiral molecules if any.

An interesting thing happened when scientist started to explore the components of meteorites and asteroids. They found amino acids, yes the very building blocks of proteins (and part of life), floating about in space. It turns out that much of the chemistry we once believed to be unique to life on earth (amino acids, sugars, hydrocarbons etc) are found haphazardly throughout space.

Back in 2000 NASA telescopes trained themselves on odd looking clouds, sometimes light-years across, found throughout the milky way. Much to scientists surprise the clouds consisted of glycolaldehyde, a simple (really the simple) sugar, which serves as the first building block of more complex sugars-Including D-ribose, the staple component of nucleotides.

When scientists discovered other sugars in meteorites, they assumed that natural process would produce a racemic mixture (50/50 mixture of 'right-handed',D, and 'left-handed',L) of enantiomers (stereoisomers which are non-superimposable mirror images, think your right and left hands). They were, as scientists sometimes are, incorrect.

When we look at the complex chemistry of space we see that the 'left-hand' or L-amino acids are more abundant by a ratio of a little more than 3:1. While the 'right-hand' or D-sugars are more abundant by a ratio of little more than 2:1. Which suggests that whatever chemical synthesis gives rise to the more complex sugars and even polypeptides (chains of amino acids) involves a catalyst that favors said form.

Another interesting point concerns seeding. A process we use in chemistry often. To briefly explain, suppose I was running a reaction which ended in crystalline formation. To speed along this crystalline formation, I might add a few crystals of the pure substance to product chamber. Which would cause the products of the reaction to favor the crystalline formation upon production.

It turns out the same process can be accomplished with chirality. If some of one form is present on the products end of a reaction, then it can 'influence' the expected ratios of said reaction. Why this works is very complex and frankly requires a degree of chemistry I'm not comfortable delving into on a message board, but know that it is experimentally verifiable--Something done by thousands of organic chemistry students across the country. What this means then, is even if chirality catalysts are even very rare, that they are there at all will influence the outcome of reactions. By favoring one enantiomer even a tiny bit, every time that enantiomer is spread out into the cosmos its greater presence will inevitably influence the outcome of uncatalyzed reactions.

On the early earth, the complex carbon based molecules would have been provided by what was available in the early solar system (which turns out to be what is still available in space today). The early earth then would have had contained more L-amino acids and more D-sugars than their counterparts (D-amino acids and L-sugars) and is it then little surprise that life adopted the most available resources?

I don't think it is, maybe you do however, in which case let's continue the discussion.

There has been lots of work, both in the past and much more recently, to discover how early nucleotides and nucleosides were formed. There formation after all, would have been one of the most important steps in life's history. The main trouble with forming nucleosides and nucleotides isn't that it's hard to do. In fact, the reactions will spontaneously happen, but the speed at which they occur is so slow that a spontaneous reaction couldn't have provided the necessary conditions for early life (maybe proto-life is a better word here) to form.

Modern life, has the benefit of billions of years of evolution behind it and the resources that come with that evolution. Namely, enzymes, which it uses to speed up reaction times to many millions and even billions of times the spontaneous rate of reaction.

Proto-life would not have had this luxury. Which means scientists have had to look elsewhere to find the answers. Some interesting recent work has shown that UV light turns out to be a great catalyst to forming all types of ribonucleosides (more support for the RNA world). This process would have been further accelerated on an early earth. Our first atmosphere here on earth was largely hydrogen and helium. Two very small elements which provided little to no protection from UV radiation bombarding us from the sun. This first atmosphere was eventually scoured from our surface by solar winds and replacing it was a much heavier atmosphere. It was perhaps, under this early first atmosphere that the backbones to life formed (indeed, we know more complex and 'modern'-looking life existed during the second atmosphere).

It turns out, when you run these reactions (glycosylamines + ribose + UV light) you get the correct handedness for nucleosides used by all life today.

Also even more interesting is, it turns out DNA and RNA are extremely efficient at UV light absorption and conversion to heat, especially in the presence of liquid water.

Which means for us (and life on earth) that the production of RNA on the early earth would have been highly, highly favored as it increased the entropy of the earth-sun system (heat turns water to steam, increasing evaporation and disorganized gaseous molecules).

The consequence of this then, would be that the necessary components for an RNA based proto-life would have been available due to the chemical kinetics of early earth.

You may now be saying, 'okay Cope, but what about amino acids'.

As has been pointed on this site before, early life would have been RNA based and had no protein component. Only after a replication system had arisen and natural selection begun did life turn down the more complex route of protein involvement. At this junction then, those early 'molecular'-organisms or even proto-cells would have been bound by the laws of supply and demand. The most available amino acids (as we know from looking else where in the cosmos) were the L-amino acids.

Naturally then when molecular system did evolve to manufacture amino acids, those which produced amino acids which fit the preexisting structure (L-amino acids) would have been the ones favored by selection.

Rather mundane if you ask me, but creationists must grasp at straws because science is so counter to their point of views.

Link

If it was a creationist that first hypothesized abiogenesis, I could see it because "I've yet to hear any biologists postulating about proteins forms and complex molecular machinery forming on its own". Doesn't it stand to "reason" that life has to begin some where, some how? Perhaps these "biologists" just don't want to go there. Its a lot easier to argue evolution from the present than it is to postulate about its beginnings.

No they certainly go there. Theoretical biologists, synthetic biologist, prebiotic biochemists etc all work in this domain of science. It is their day job.

What I was pointing out is that modern biologists don't claim that proteins and complex molecular machinery doesn't "randomly" form on its own. That's important because it is a common creationist strawman creationist have a tendency to use to misinform their readers and followers. For the exact reason creationist claim that "complex cellular machinery" couldn't have arisen by chance alone, biologists don't claim that it did. You have to be careful reading creationist literature--Many are simply misinformed and ignorant of their lack of information about biology and science. In that they may mean well, but simply don't know what they are talking about. Others however, are intentionally deceitful.

All the very simple forms of life described above rely on other "life" (more complex life) to survive, symbiotic or parasitic, which in itself is a highly complex adaptation.

Yes, living things don't evolve in a vacuum......The selective forces that act upon them are the sum total of their environment--Both biotic and abiotic factors.

I always thought abiogenesis was part of the theory as I was taught at univ, ie the pool of goo, spark, and life starts. That biologists don't postulate about it is not a surprise. It seems more like the Achilles heel to whole theory.

No. Abiogenesis is not part of evolutionary theory (the modern synthesis is the name scientists use--"Evolutionary theory" is the nonspecific name layfolk use), as I explained above--Science is specific.

The "spark" you are referring too is the Miller-Urey experiment. Again this is often used by creationists as a strawman. M-U didn't show how life starts, it did show how complex organic molecules form--Particularly certain amino acids.

Hey, copa

I think that is one of the issues that throws people off, along with the idea that classifications are human labels as opposed to nature's labels. I understand what you mean by "no species division." However, please realize that those divisions are often publicized in that manner -- "We found a partial skeleton! It's an Australopithecus afarensis!" -- so it's only natural for us to use such terms in discussion.

Please understand that the difficulty for persons like me is partially the staggering number of allele changes that would have to occur between, for example, Maelestes gobiensis and my house cat. I am aware that it was not an overnight change, and that we had previously discussed re-usage of existing features. However, part of what I don't understand is this (unless what I'm referencing an urban legend): for M. gobiensis to evolve to a house cat would require many, many changes over 75 million years. How is it that over that same time period, some animals experienced very little change other than size? (Alligator, tortoise.)

JK you seem like a smart and open-minded guy, if you don't mind me complimenting you ;) . I believe I read on another topic you are a teacher, correct? Let's look at this like a continuing-education/learning experience again. I'll place my bet on you being smart enough to answer your own question with your reasoning prowess :tu: .

First lets review the 4 things natural selection requires;

1. Variation in a population

2. Some of that variation is passed on; we call this heredity

3. An environment with a finite amount of resources

4. Differential survival and reproduction (ie; survival and reproduction is not random, not each member in a population has an equally likely chance to survive and reproduce).

Knowing those 4 things above then, can you do as Darwin did and figure out what is doing the selecting?

Let's look at an analogy that maybe useful for you to figure it out; Artificial selection. Why is that my boxers look the way they do? They don't breed randomly, in fact who breeds in the boxer population is highly selected. But who selects who breeds and who dies in the boxer gene pool? Dog breeders do of course. So the traits which make a boxer a boxer are from selection and this selection comes from people's choice.

Now compare that to the above with natural selection: "who" is doing the choosing? How the "choice" of selection being made above in light of those 4 things? Those aren't rhetorical, I'd like you to reply and answer them ;)

***Special caveat here JK, its more complicated than this because not all traits a population has is because of natural selection. Natural selection is the only process which is capable of producing adaptive evolution, but not all traits are adaptations. Things like genetic drift or sexual selection for example, also play a role in the traits a population has. Remember in biology adaptation has a specific definition; traits favored by natural selection. But for the moment, let's leave those other modes (or better; explanations) of biological evolution out of the discussion for now as we cover the basics--As they are more complex topics that require more biology knowledge to understand.

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J. K.

Now compare that to the above with natural selection: "who" is doing the choosing? How the "choice" of selection being made above in light of those 4 things? Those aren't rhetorical, I'd like you to reply and answer them ;)

Keep in mind that I approach things from the mathematical approach of a computer nerd: identify what exists, and analyze how they function and interact. In that sense, I would rephrase the four requirements in the following manner. A population can have hereditary variation. An environment has a finite amount of resources. Permanent change due to hereditary variation is influenced by the environment. Hereditary variation introduces a change; environmental influence fixes the change.

I do understand your statement about genetic drift. If natural selection was the sole process, then there would only be one continuously changing organism in the world.

To answer your questions, in the realm of nature, the “who” that does the choosing is the environment. The “how” is through the process of beneficial hereditary variation. In the dog example, the “who” is the breeder, and the “how” is choice by observed trait.

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Copasetic

Keep in mind that I approach things from the mathematical approach of a computer nerd: identify what exists, and analyze how they function and interact. In that sense, I would rephrase the four requirements in the following manner. A population can have hereditary variation. An environment has a finite amount of resources. Permanent change due to hereditary variation is influenced by the environment. Hereditary variation introduces a change; environmental influence fixes the change.

I do understand your statement about genetic drift. If natural selection was the sole process, then there would only be one continuously changing organism in the world.

To answer your questions, in the realm of nature, the “who” that does the choosing is the environment. The “how” is through the process of beneficial hereditary variation. In the dog example, the “who” is the breeder, and the “how” is choice by observed trait.

Okay, to the boldface: full stop there. That is a good answer, but now I want to add a new word to our discussion. We often say "the environment" but we need to get more specific, what we ought to be saying instead of environment is the word niche. The niche of an organism then, we can think about as its relationship with all those abiotic and biotic things in its environment. Or to put more simply; "it's place in the world". Each population occupies a niche and does so well because of selection adapting those populations for that specific niche.

Let's go back to your question now which generally summed up was; why over the millions of years did the lineage which led to cats diversify and change so much, but the lineage of say; crocodilians remain (relatively) unchanged?

Too specific, let see if we can make it more general for you;

Why does one lineage change, while another lineage changes only a little? (Important point here: regardless of whether you "see" the changes ALL POPULATIONS CHANGE ACROSS GENERATIONS. Remember that is the fact of biological evolution: that across generations allele frequencies change. So even if a population "looks" the same, the allele frequencies still change.--Important point and let me know that you understand that).

So taken in light of the above word (niche) and your thoughts above can you answer the question underlined there?

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J. K.

Why does one lineage change, while another lineage changes only a little? (Important point here: regardless of whether you "see" the changes ALL POPULATIONS CHANGE ACROSS GENERATIONS. Remember that is the fact of biological evolution: that across generations allele frequencies change. So even if a population "looks" the same, the allele frequencies still change.--Important point and let me know that you understand that).

So taken in light of the above word (niche) and your thoughts above can you answer the question underlined there?

To answer the underlined question: adaptive selection is unnecessary for an organism which is adequately suited to its niche. Presumably, a crocodilian remains relatively unchanged (in appearance) because it is adapted to its niche. I understand that you are saying that somatic change is not necessarily a result of changes in alleles, and that all organisms experience allele changes across generations.

That just leads to some further questions for me.

Isn’t somatic change in fossils used as proof of evolution, since genetic material cannot be obtained from fossils?

Adaptive selection isn’t the only driving force behind evolution; isn’t there also mutation and genetic drift? During the time period in which Maelestes diversified to such a wide range of mammalians, it seems mathematically improbable that crocodilians would have experienced little change.

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FurthurBB

<!--quoteo(post=1633265:date=Apr 17 2007, 10:56 AM:name=thaphantum)--><div class='quotetop'>QUOTE(thaphantum @ Apr 17 2007, 10:56 AM) 1633265[/snapback]</div><div class='quotemain'><!--quotec-->you said all that... none of contained any proof that evolution is correct... nor did it contain any proof that religion is wrong...

when Darwin OBSERVED nature and came to the conclusion the we evolved... is that religion or science? and why?

when Christians observe nature and come to the conclustion that God exists... is that religion or science? and why?

please think about it before you answer... <img src="http://www.unexplained-mysteries.com/forum/public/style_emoticons/<#EMO_DIR#>/thumbsup.gif" style="vertical-align:middle" emoid=":tu:" border="0" alt="thumbsup.gif" /><!--QuoteEnd--></div><!--QuoteEEnd-->

Don't be snarky.

I didn't say anything about evolution. Evolution of the species is a theory that seems to currently best reprsent the facts for the majority of the world and the majority of scientists. The theory of Evolution couldn't give a rats ass about religion or proving it is wrong. I guess you just answered my question you believe creationism is a religion. So therefore it is not science.

Darwins observations are observations. In that he included them in making his initial theories - it would be part of the scientific method. Modeling the world based on all of the observed facts about the world.

When people of faith observe nature and come to the conlustion that God exists - that is a matter of faith or religion. This is because they ignore most of the observed facts about the world. We make a leap of faith that God exists.

And contrary to other threads, Christianity is not the same as the crazy fundamentalism in the US. ALL Christians do not beleive the rubbish that some spew. There are a majority of us that are Christian, believe in God and JC, and that the theory of evolution is perfectly ok.

Not to mention the theory evolution and its predictions has been practically used in industry for over 50 years to provide 100,000s of new procedures, techniques, and products with unbelievable reliability.

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Copasetic

To answer the underlined question: adaptive selection is unnecessary for an organism which is adequately suited to its niche. Presumably, a crocodilian remains relatively unchanged (in appearance) because it is adapted to its niche. I understand that you are saying that somatic change is not necessarily a result of changes in alleles, and that all organisms experience allele changes across generations.

You had a dog and bingo was his name-o. The niche they occupied stayed relatively stable over that time period, ergo they were evolutionary "stasis--Remember we say selection is "environmentally driven", when really what we mean is it is niche driven.

That just leads to some further questions for me.

Shoot.

Isn’t somatic change in fossils used as proof of evolution, since genetic material cannot be obtained from fossils?

Adaptive selection isn’t the only driving force behind evolution; isn’t there also mutation and genetic drift? During the time period in which Maelestes diversified to such a wide range of mammalians, it seems mathematically improbable that crocodilians would have experienced little change.

You're forgetting something very, very important. Selection is an equal opportunity employer ;) . The door swings both ways. That is to say JK, that not only does selection select beneficial variation, but also culls maladaptive variation. Positive selection, selection for traits that aid in niche living and negative selection, selection against traits that aren't useful for niche living. So while new traits are cropping up during times of stasis, the population is already well adapted so many new traits will undergo negative selection.

That is a very important concept to understand. In fact I'd you should even think about it as selection spends more "time" culling those with low fitness than it does "picking the good ones" (understand here fitness refers to reproductive success). Think about it, it will make sense.

We have a special name for this kind of selection where we are selecting against extremes in traits on a bell-curve distribution: stabilizing selection.

Selection_Stabilizing.jpg

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J. K.

http://news.yahoo.com/primitive-eyeless-worlds-deepest-land-animal-discovered-050602455.html

Copasetic, I just saw this article today, and it ties in with what we've been discussing.

"P. ortobalaganensis has no eyes and long antennae," said researcher Enrique Baquero, a taxonomist at the University of Navarre in Spain. These features are typical of troglobionts, or cave dwellers. "Nevertheless, it has pigment, usually absent in animals that are strict troblobionts." (The creature has a grayish body covered with darker spots.)

Baquero speculated that P. ortobalaganensis only reached such low depths recently. This would explain its lack of extreme adaptations to that depth. For instance, the organism has not yet lost its pigment as many cave creatures have. Coloration helps protect against the sun, show off to mates and camouflage against predators and prey on the surface, but is pointless in lightless caves."

Okay, the organism has only recently inhabited its niche, and still retains pigment/spots which presumably were of benefit in a previous niche. The article implies that the pigment will disappear. My question is: since the pigment is neither a benefit or a deficit, why would it disappear?

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Copasetic

http://news.yahoo.com/primitive-eyeless-worlds-deepest-land-animal-discovered-050602455.html

Copasetic, I just saw this article today, and it ties in with what we've been discussing.

"P. ortobalaganensis has no eyes and long antennae," said researcher Enrique Baquero, a taxonomist at the University of Navarre in Spain. These features are typical of troglobionts, or cave dwellers. "Nevertheless, it has pigment, usually absent in animals that are strict troblobionts." (The creature has a grayish body covered with darker spots.)

Baquero speculated that P. ortobalaganensis only reached such low depths recently. This would explain its lack of extreme adaptations to that depth. For instance, the organism has not yet lost its pigment as many cave creatures have. Coloration helps protect against the sun, show off to mates and camouflage against predators and prey on the surface, but is pointless in lightless caves."

Okay, the organism has only recently inhabited its niche, and still retains pigment/spots which presumably were of benefit in a previous niche. The article implies that the pigment will disappear. My question is: since the pigment is neither a benefit or a deficit, why would it disappear?

Let me answer your question with a question: Suppose you didn't like the taste of peanuts. So you didn't eat them. They just would sit in your house, unused. Would you keep buying them? Or would you spend your money on something else?

Remember there is always a "cost" in biology; its not free to make complex molecules and the currency organisms use (energy from chemistry) isn't infinite--Just like your bank account. So it comes down to balancing the proverbial check book. If the cost is great enough on an "unused item" then we would expect that item to add a little more weight to that negative selection side of the scale.

On the other hand, things which only tip the balance a little bit, we would expect to take more time to be "lost" to selection. Something like having an eye, expensive to maintain AND a potential route to be breached by pathogens, would have lots of "weight" on the scale and we would expect to be lost quickly or at least early on in the change of niche. While something like pigment, that maybe only associated with a small "weight" we would expect to be lost later on in the move to the new niche.

Note: I haven't had a chance to read the article yet.

Edited by Copasetic

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J. K.

Remember there is always a "cost" in biology; its not free to make complex molecules and the currency organisms use (energy from chemistry) isn't infinite--Just like your bank account. So it comes down to balancing the proverbial check book. If the cost is great enough on an "unused item" then we would expect that item to add a little more weight to that negative selection side of the scale.

On the other hand, things which only tip the balance a little bit, we would expect to take more time to be "lost" to selection. Something like having an eye, expensive to maintain AND a potential route to be breached by pathogens, would have lots of "weight" on the scale and we would expect to be lost quickly or at least early on in the change of niche. While something like pigment, that maybe only associated with a small "weight" we would expect to be lost later on in the move to the new niche.

I have to admit that I failed economics in high school, and I don't quite have a handle on what you're saying. It seemed like the economy was being described as a living organism, with a mind of its own that makes its own choices apart from human input. To me, regarding the 'weight' thing you're mentioning is almost the same thing. We can see that an eye is a more complex feature than spots, but we're looking at it with human intelligence. Forgive the anthropomorphism, but how would the organism 'know' that? I see the point about the energy currency involved, but what force drives the change? Where is does the knowledge that the eye is more risky come from?

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Copasetic

I have to admit that I failed economics in high school, and I don't quite have a handle on what you're saying. It seemed like the economy was being described as a living organism, with a mind of its own that makes its own choices apart from human input. To me, regarding the 'weight' thing you're mentioning is almost the same thing.

No, the "economy" is natural selection--The organism doesn't have a choice in the matter. The analogy with weights was to get you picture it like a scale. Where selection on different phenotypes tips the scales of the gene pool in one direction or another. Things that "weigh" a lot and bend to the negative selection side are quickly culled out of the gene pool, etc.

Follow me?

We can see that an eye is a more complex feature than spots, but we're looking at it with human intelligence. Forgive the anthropomorphism, but how would the organism 'know' that?

It doesn't know anything. Remember selection works on differential reproduction and survival. Eyes "cost" a lot to make. They require lots of ATP (where our cells get 'energy' to maintain homeostasis), lots of immune surveillance, they are prone to infection and developmental problems, etc.

So if a population didn't have eyes, then the "weight" of eyes on the scale of selection would tip it heavily toward the negative selection side. Hence loosing it "quickly" (geologically speaking).

Pigment on the other hand, is much cheaper to make and has less negative costs associated with it than eyes--Ergo, eyes are lost before pigment.

I see the point about the energy currency involved, but what force drives the change?

Can you clarify this? Are you asking how genetic change happens? Or are you asking how the selection against the features happens?

Where is does the knowledge that the eye is more risky come from?

Our knowledge? Or do you think its the organism's knowledge? Remember organisms don't choose. Selection is through differential reproduction and survival. If you get an infection in your eye and die before you make it to reproductive age then you and all the alleles which say "make an eye" are lost from the gene pool. If you make an eye and you don't need it, your body has to spend resources (ATP) on maintaining it. From a homeostatic point of view then, that is 'energy' you could have used for something else--Or better resources you didn't have to acquire in an environment with limited resources. If members of the population then with less alleles that say "make and eye" out reproduce members with those alleles then all the alleles in the population which say "make an eye" will eventually have their frequency reduced to 0 (or at the least very low).

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