Evolution questions: round 3

[Krok]

Not sure if this is the right place, my question is on radiometric dating.
I understand that radioactive isotopes decay at a measurable and constant rate to a specific daughter isotope. But how do scientists know that from the formation of X, the isotopes that they are looking at didn't get there after, or some didn't become lost along the way?
For example, uranium to lead, how do scientists know that X amount of uranium and lead was present at the formation of said rock, and that no new uranium or lead got incorporated, or that no uranium or lead escaped? Same thing with all of them, C14, K-Ar, Ar-Ar, Rb-Sr, and so on.

Hi RedOne, I'll answer this with reference to the K-Ar method, as it is the one I'm most familiar with. This is a very basic answer, do go and look at scientific references to see a more complete story.

We regularly use Biotite crystals to date the rocks, as biotite is a very common mineral formed when a rock crystallises from magmas.

The chemical formula of biotite is K(Mg,Fe)3AlSi3O10(F,OH)2.

Because Ar is a noble gas, it doesn't take part in any chemical reactions and can thus not be incorporated in the crystal structure of Biotite when the crystal forms. There would thus be no Ar present in the crystal structure of biotite when the crystal is formed. When we measure the Ar in the crystal structure of Biotite, we know that all the Ar present in the crystal structure is a result of radioactive decay of K (Ar can be incorporated in the form of fluid or air bubbles in the crystal, but these are not part of the crystal structure and we can eliminate these as far as possible).

As long as the crystal exists, we can thus measure the K and Ar ratio in the crystal structure. Furthermore, we can test the chemical formula of that crystal to test the chemical composition of that biotite crystal to see if the chemical formula is different; we can look at it under the microscope to see if we can find phenonema like zoning, etc. to see if the rock has been partially melted since formation and other elements could have been incorporated as part of the crystal, etc.

Geologists are not as dum as creationists try to convince people the are!

 

[painted wolf]

Any links to how the electric eel supposedly evolved? I can't find much besides this....

Scientists Push for Electric Eel Genome Research | GenomeWeb Daily News | GenomeWeb

Cool story... we obviously don't have all the details... but...

The "Electric eel", is actually a member of the "knife fish" family and more distantly related to catfish.
The electric organs are present in all the other members of the family and is used in electrolocation... that is, producing an electric charge to find objects. The electric eel has the largest of the bunch, and having such a massive generator means they can produce the biggest "zap".

All knifefish can produce a "zap" but not as powerfully as the Electric eel... so there are plenty of examples of what an ancestral Electric eel would have been like. The further away in relatedness from the Electric eel you go the weaker the "zap" produced by the knifefish.

We can see parallel evolution in other more distant relatives of the electric eel in the "electric catfishes" a group of catfish from Africa, who share a similar lifestyle and environment as the South American Electric eel... who also have the same types of electric organ and in those members with larger organs you also get bigger "zaps".
What is really cool, is you can actually teach these catfish to "zap" on command in return for a treat.

The organs themselves are actually modified swimming muscles. You can trace lineages based on what types of swimming muscles the organs originated from (tail, body, even the muscles that move the eyes)
Muscle produces an electric charge anyway... but in these examples it has been amplified. In fish more distantly related to the big "zappers" the current is not controlled and happens as the organs flex during swimming. They also produce the lowest voltage and use it more for passive detection. Electrorecption is even more common among fish than electro-production.

Once we have the genome of the Electric eel we can start to compare it to it's relatives and find the specific evolutionary changes that make it such a "supper zapper". But that's a fair bit of work still ahead of us.

Hope this helps.

wa:do

 

[painted wolf]

Hi RedOne, I'll answer this with reference to the K-Ar method, as it is the one I'm most familiar with. This is a very basic answer, do go and look at scientific references to see a more complete story.

We regularly use Biotite crystals to date the rocks, as biotite is a very common mineral formed when a rock crystallises from magmas.

The chemical formula of biotite is K(Mg,Fe)3AlSi3O10(F,OH)2.

Because Ar is a noble gas, it doesn't take part in any chemical reactions and can thus not be incorporated in the crystal structure of Biotite when the crystal forms. There would thus be no Ar present in the crystal structure of biotite when the crystal is formed. When we measure the Ar in the crystal structure of Biotite, we know that all the Ar present in the crystal structure is a result of radioactive decay of K (Ar can be incorporated in the form of fluid or air bubbles in the crystal, but these are not part of the crystal structure and we can eliminate these as far as possible).

As long as the crystal exists, we can thus measure the K and Ar ratio in the crystal structure. Furthermore, we can test the chemical formula of that crystal to test the chemical composition of that biotite crystal to see if the chemical formula is different; we can look at it under the microscope to see if we can find phenonema like zoning, etc. to see if the rock has been partially melted since formation and other elements could have been incorporated as part of the crystal, etc.

Geologists are not as dum as creationists try to convince people the are!

Thanks for the answer!

wa:do

 

[Krok]

Thanks for the answer!
wa:do

Thanks.
Geologists are not as dum as creationists try to convince people they are.
Another example: The U-Pb methods.
The favorite mineral is Zircon (chemical formula ZrSiO4). Uranium easily substitutes for Zr during crystallisation, while lead is strongly excluded, due to the size of the Pb-ions. This means the clock is truly set at zero when zircon forms. Voila!
(Creationist sources won't ever tell their believers about things like this, would they? If they did, they not only have to disregard the sciences of biology, geology, physics, but also the science of chemistry, too. 'But, but Chemistry is an "operational" science, not a "historical" science, I can hear them say!')

 

[~Amin~]

Thanks for the input guys.
There are a few more questions stuck in my mind, and a thought i would like to share.
1.Where did the information in the human genome come from?
2. Is it possible that through careful observation, analysis, research through scientific methods, and through our rapid technological advancement, we can explain the appearance of human chromosome 2, other than the way suggested?

Now to my thought, no body has seen the fusion of two primate chromosomes, into one human chromosome, so in a way isn't this only having faith that it occurs, because it appears so? its like for example when a ''creationist says hey i believe in God because existence looks designed, and therefore is designed.

 

[painted wolf]

Thanks for the input guys.
There are a few more questions stuck in my mind, and a thought i would like to share.
1.Where did the information in the human genome come from?

I'm not sure I understand the question... we know mutations change the genome and we know what changes there are between humans and chimps. We don't yet know what all of the changes do yet, but we know exactly what the differences are and what kinds of mutations would have caused them.

Some are from duplication errors, some from single nucleotide changes and so on.

2. Is it possible that through careful observation, analysis, research through scientific methods, and through our rapid technological advancement, we can explain the appearance of human chromosome 2, other than the way suggested?

Chromosomal fusions are pretty distinctive events, it's hard if not impossible to confuse them with something else.

The only other way I can think of, if to have a god who is a sneaky trickster. I personally don't think of god that way so...

Now to my thought, no body has seen the fusion of two primate chromosomes, into one human chromosome, so in a way isn't this only having faith that it occurs, because it appears so? its like for example when a ''creationist says hey i believe in God because existence looks designed, and therefore is designed.

Not just because it appears so... though to be honest it's the only way it appears... but because of the way chromosomes behave during mitosis. We have seen fusion in other animals... such as domestic cattle, sheep, horses and both wild and domestic mice.

An observed chromosome fusion. Hereditas 1998;129(2):177-80
A new centric fusion translocation in cattle: rob (13;19). Molteni L, De Giovanni-Macchi A, Succi G, Cremonesi F, Stacchezzini S, Di Meo GP, Iannuzzi L. Institute of Animal Husbandry, Faculty of Agricultural Science, Milan, Italy..

A new Robertsonian translocation has been found in cattle. A bull from Marchigiana breed (central Italy) was found to be a heterozygous carrier of a centric fusion translocation involving cattle chromosomes 13 and 19 according to RBA-banding and cattle standard nomenclatures. CBC-banding revealed the dicentric nature of this new translocation, underlining the recent origin of this fusion. In fact, both the bull's parents and relatives had normal karyotypes. In vitro fertilization tests were also performed in the bull carrying the new translocation, in two bulls with normal karyotypes (control) and in four other bulls carrying four different translocations.
PMID: 10022084, UI: 99146110

Survival of Chromosomal Changes

Again, seeing it happen in nature and then finding it in ourselves means either it happened naturally.... or that God is trying to deceive us when he made us with a chromosome that bears all the hallmarks of being fused.
And again, I don't think God is deceitful.

wa:do

 

[~Amin~]

I'm not sure I understand the question... we know mutations change the genome

Where does the genetic information come from? for example in my DNA its recorded the colour of my eyes hair, how tall i am etc etc, basically the person i am is contained in the DNA, where did this come from?

The only other way I can think of, if to have a god who is a sneaky trickster. I personally don't think of god that way so...

You have mentioned this a few times, but you didn't mention that it belongs to Kenneth Miller, he also said:
"if these guys REALLY share a common ancestry, that ancestry EITHER had 48 chromosomes or 46 chromosomes, now IF it had 48 chromosomes which PROBABLY true, what must of happened, is that one pair of chromosomes must of fused''

Have i missed something? this whole paragraph seems doubtful, with humbleness from myself, if i have misunderstood the biological language, please explain i am willing to except.

 

[johnhanks]

Where does the genetic information come from?

I'm not speaking for PW here, who I'm sure will answer in her own eloquent way, but would like to insert two-penn'orth if I may.

Genetic information consists of the association of triplets of nucleotides with the insertion of specific amino acids into proteins. As far as we can ascertain, the association is effectively arbitrary: there is nothing intrinsic to the amino acid phenylalanine that would make UUU its logically necessary codon. Genetic information, in other words, bears no trace of having been 'planned' and probably has random origins.

... for example in my DNA its recorded the colour of my eyes hair, how tall i am etc etc, basically the person i am is contained in the DNA, where did this come from?

From billions of years of functionally efficient proteins extending the lifespan and/or reproductive success of organisms possessing nucleotide sequences coding for them. Alternatively (and more probably in the case of your eye colour) by genetic drift replacing perfectly efficient nucleotide sequences with equally efficient ones.

 

[Looncall]

Where does the genetic information come from? for example in my DNA its recorded the colour of my eyes hair, how tall i am etc etc, basically the person i am is contained in the DNA, where did this come from?


You have mentioned this a few times, but you didn't mention that it belongs to Kenneth Miller, he also said:
"if these guys REALLY share a common ancestry, that ancestry EITHER had 48 chromosomes or 46 chromosomes, now IF it had 48 chromosomes which PROBABLY true, what must of happened, is that one pair of chromosomes must of fused''

Have i missed something? this whole paragraph seems doubtful, with humbleness from myself, if i have misunderstood the biological language, please explain i am willing to except.

You should note that chromosomes carry very specific chemical structure and that that structure can be discovered. The two parts of the fused chromosome have the same structure as the separate ones found in related animals. It would be very perverse to claim that the fused chromosome developed entirely on its own. You do not get to sneak gods into biology by pretending to be confused.

 

[painted wolf]

Where does the genetic information come from? for example in my DNA its recorded the colour of my eyes hair, how tall i am etc etc, basically the person i am is contained in the DNA, where did this come from?

From your parents and the mutations that happened when their chromosomes were being stitched together to make you. We all have between 100 and 200 mutations that make us unique.

Your parents got it from their parents (plus mutations) all the way back to the first living things.

You have mentioned this a few times, but you didn't mention that it belongs to Kenneth Miller, he also said:
"if these guys REALLY share a common ancestry, that ancestry EITHER had 48 chromosomes or 46 chromosomes, now IF it had 48 chromosomes which PROBABLY true, what must of happened, is that one pair of chromosomes must of fused''

It doesn't "belong" to Ken. Nor did he discover it. He does use it as an example in his talks though.
The evidence is public domain with the publishing of both the human genome and chimp genome... work done by large teams of researchers.

Have i missed something? this whole paragraph seems doubtful, with humbleness from myself, if i have misunderstood the biological language, please explain i am willing to except.

It's not doubtful... it's the set up for the evidence. It's only an introductory statement.
Introductory statements in science are phrased as questions (known as hypotheses)...

If X is true then 1 or 2 must be true... if 2 is probably true then Y must have happened.... now let me show the the evidence for why 2 is actually true.

If you watch or read the rest of Ken Millers presentations then you see he isn't doubtful at all. Your quote cuts out the very important "now let me show you the evidence for why 2 is actually true" part.

wa:do

 

[RedOne77]

Thanks to all for the radiometric information.

 

[painted wolf]

Like I said.. fossil marine inverts like corals. It's not 100% accurate, but then nothing is carbon dated past 60,000 years so...

wa:do

 

[RedOne77]

Sorry, I didn't see your post earlier, just now saw it. Hehe

 

[painted wolf]

No prob.

wa:do

 

[Krok]

Thanks to all for the radiometric information.

Pleasure and thanks RedOne
I only know about the basics (of some methods), but if you want to learn more about it from someone who knows a lot more than me, read Roger Wiens' article on the website of the ASA. ttp://asa3.org/ASA/resources/Wiens.html

The different dating methods all represent speciality areas (the last number was 47 or 48 different radiometric methods!); it's very unusual to find one guy to be a specialist on more than a few of them. The part that creationists always ignore is: all these vastly dissimilar methods give similar answers! Coincidence? I think not. Then there's exciting other (relatively new) methods as well. Try to look op thermoluminescence!

 

[painted wolf]

ba-da-bump

wa:do

 

[Shermana]

Explain Cannibinoid receptors.

 

[painted wolf]

Explain Cannibinoid receptors.

Can you narrow that down a bit?

To be as general as possible...

They are receptors bound to cellular membranes that respond to cannibinoids/endocannibinoids.... which are lipids that can act as messengers between cells.

Receptors are protein complexes that react with certain types of chemicals in the body. These reactions can be temporary or permanent, but are usually temporary.

For example Amnesiac Shellfish Poisoning is caused when Demoic Acid binds permanently to AMPA receptors because it is almost identical in structure to those neurotransmitters... but different enough that the receptor can't unbind it once it latches on.

wa:do

 

[Shermana]

To be more precise, What would cause them to develop? They show up in far more than just humans. How were they involved with survival? What would cause them to mutate into existence?

 

[Pegg]

My question is how did seeds evolve.