Trilobites - Antecedents and Successors: QUESTIONS

This forum is for the discussion of the evidence for evolution. Anyone is welcome to post, however, scripture is not allowed. As the title says, Science Only please!

Moderator: Moderators

Trilobites - Antecedents and Successors: QUESTIONS

Postby Jaf » Wed Dec 06, 2006 11:30 pm

On Wed, 06 Dec 2006 17:12:02 -0600, you wrote:

But only the SRY gene is active in sex discrimination [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?call=bv.View..ShowSection&rid=gnd.section.156]

It doesn't say that.
The last line -
"This has been particularly important in discovering the interactions of SRY
with other genes in male sex determination." gives a clue.
note - <<interactions of SRY with *other* genes in male sex determination.>>
which suggests at least three genes are involved.
--
JAF
anarchatntlworldfullstopcom
Keep Science Scientific
BCSE http://bcseweb.org.uk
Jaf
 
Posts: 73
Joined: Sat Oct 07, 2006 4:59 pm
Location: Scunthorpe, N.Lincolnshire

Re: Trilobites - Antecedents and Successors: QUESTIONS

Postby tomrees » Thu Dec 07, 2006 9:32 am

John Flemming (Jaf) wrote:The last line -
"This has been particularly important in discovering the interactions of SRY with other genes in male sex determination." gives a clue. note - <<interactions of SRY with *other* genes in male sex determination.>> which suggests at least three genes are involved.

Yes, sex is not an either-or thing. SRY is fundamental - but you can have maleness without it or a Y chromosome. e.g. Gene mutation turns girls into boys What's interesting is that both SRY and RSPO1 are involved in triggering testes development - although not the full gamut of secondary sexual characteristics.

Hmm getting a bit off-topic here...
"The world holds two classes of men - intelligent men without religion, and religious men without intelligence." Abu'l-Ala-Al-Ma'arri (973-1057)
tomrees
 
Posts: 21
Joined: Sun Dec 03, 2006 10:59 pm
Location: Brighton, UK

Re: Trilobites - Antecedents and Successors: QUESTIONS

Postby George Jelliss » Thu Dec 07, 2006 4:45 pm

tomrees wrote:Hmm getting a bit off-topic here...


Yes, but it's very interestingly off-topic!

It just shows how difficult it is to write popular science, understandable to the general public, and at the same time satisfy the requirements of science for objective accuracy.

There is so much detail now known to specialists. This is why it is no longer possible for one person to know everything about all branches of knowledge (if indeed it ever was). Perhaps you have to go as far back as Aristotle for that!

This is one way that religion has an advantage. All you have to do is accept an interpretation of the "revealed" text and then interpret any new knowledge so as to fit in with the preconceived worldview. So much less work and effort is involved.
GPJ
User avatar
George Jelliss
 
Posts: 204
Joined: Sat Oct 07, 2006 4:59 pm
Location: St Leonards on Sea (UK)

Re: Trilobites - Antecedents and Successors: QUESTIONS

Postby tomrees » Thu Dec 07, 2006 9:07 pm

George Jelliss wrote:
tomrees wrote:Hmm getting a bit off-topic here...


It just shows how difficult it is to write popular science, understandable to the general public, and at the same time satisfy the requirements of science for objective accuracy.

There is so much detail now known to specialists. This is why it is no longer possible for one person to know everything about all branches of knowledge (if indeed it ever was). Perhaps you have to go as far back as Aristotle for that!


Agree with that totally - that's why wikis are so great.

This is one way that religion has an advantage. All you have to do is accept an interpretation of the "revealed" text and then interpret any new knowledge so as to fit in with the preconceived worldview. So much less work and effort is involved.


Ahh but it's all in choosing the interpretation. Followers of the same religion can be saints and suicide bombers, after all.
"The world holds two classes of men - intelligent men without religion, and religious men without intelligence." Abu'l-Ala-Al-Ma'arri (973-1057)
tomrees
 
Posts: 21
Joined: Sun Dec 03, 2006 10:59 pm
Location: Brighton, UK

Re: Trilobites - Antecedents and Successors: QUESTIONS

Postby Monad » Wed Dec 13, 2006 7:59 pm

Joachim Schlick wrote:I’ve searched your Forum for the word ‘trilobite’ and it came up with ‘no matches found’.

I found this description of the trilobite on the Net (Wikipedia – which believes as a matter of editorial policy that evolution is proved and that intelligent design is nonsense. I summarise).

I have some questions for the expert evolution scientists on this Forum - see below.

For one of the earliest creatures in the fossil record - its developing a very precise 543 million years ago according to the article – the trilobite seems to have a surprising number of very well developed features.

I’ll list some of these key features:

1. A head with several segments
2. A thorax with ‘freely articulating segments’
3. A tail with fused-together segments
4. The ability to ‘curl up’
5. A pair of antennae
6. A multiple set of legs each with six segments, one with a ‘feather-like epipodite’ used both for respiration and swimming
7. Three sets of lobes, two pleural, one axial - hence ‘trilobite’
8. An armoured ‘exoskelton’ on top composed of calcite
9. A pair of crescent-shaped ‘compound’ eyes with up to 15,000 tiny lenses, each being formed in the shape of an elongated prism, mostly apparently capable of seeing in the dark ocean depths, some having a ‘doublet’ structure said to give ‘a superb depth of field’, and arranged hexagonally
10. Horns
11. The ability to survive and flourish thousands of feet under the sea.

Now some genuine questions:

A. What is known about the evolutioanry antecedents of the trilobite, and is there any evidence of them in the fossil record?

B. Whay creatures if any were the evolutionary successors of the trilobite, and is there any evidence of them in the fossil record?

C. By what known genetic mechanism did trilobites gain up to 15,000 elongated prism-shaped lenses arranged hexagonally and capable of seeing in the dark?

D. How much DNA would be needed to code for 15,000 prism-shaped lenses arranged hexagonally and capable of seeing in the dark?

E. Which creature first developed eyes - and how and when did
they do so?

F. By what evolutionary mechanism did trilobites acquire ‘feather-like epipodites’ to help them breathe and swim?

G. Is it a scientific statement - or not - to say: “I consider that the
data relating to the trilobite is better evidence for intelligent design than for evolution”?
And finally:

H. By what mechanism did non-life become life and when (roughly) did this happen?


For detailed information on Trilobites and their origins I would suggest this site:

http://www.trilobites.info/

and the following links explore the question of trilobite and early arthropod origins in more detail:

http://www.trilobites.info/origins.htm

http://www.trilobites.info/background3.html

the last page looks at some of the earliest "proto-arthropods" and this is important because what you described above as a trilobite "bauplan" in fact has it's evolutionary origins in creatures like this. A good article on these early origins and some of the recent powerful evidence for common descent is found here:

http://pharyngula.org/index/weblog/comm ... /#continue

As to your questions:

A. What is known about the evolutioanry antecedents of the trilobite, and is there any evidence of them in the fossil record?

See above and read - there is quite a lot now.

B. Whay creatures if any were the evolutionary successors of the trilobite, and is there any evidence of them in the fossil record?

There are none - Trilobites are not thought to have left direct decendents though several sister groups are still around (probably one of the closest is Limulus but not that close even though it's larvae look very Trilobite like)

C. By what known genetic mechanism did trilobites gain up to 15,000 elongated prism-shaped lenses arranged hexagonally and capable of seeing in the dark?

Probably the same way arthropods get segments - by duplication (tagmosis is one form of this process). Not all Trilobites have so many lenses.

D. How much DNA would be needed to code for 15,000 prism-shaped lenses arranged hexagonally and capable of seeing in the dark?

Probably the same amount as with one lense - surely you don't think repetition of the same set of comands 15,000 times requires any more information than repeating it say twice? Do you need 10 cookery books to cook 10 identical cakes?

E. Which creature first developed eyes - and how and when did
they do so?

Eyes go back a long way. Even some bacteria have the ability to sense and move into, or away from light (as well as other forms of energy like magnetic forces and heat). Many organisms have a simple spot of pigment that is light sensitive. That is the starting point. From there to an eye is not something that would happen at once but even today one can find living examples of every single step in the process from a simple blob of pigment to a complex eye in several groups (in fact in Molluscs you can find every stage within that one group). Dawkins has a great discussion of eye evolution in "Climbing Mount Improbable"

F. By what evolutionary mechanism did trilobites acquire ‘feather-like epipodites’ to help them breathe and swim?

Read the links I posted

G. Is it a scientific statement - or not - to say: “I consider that the
data relating to the trilobite is better evidence for intelligent design than for evolution”?

Again you should read "Climbing Mount Improbable". Certainly many complex lifeforms appear at first glance something like a machine and we all know machines are made by people. But living organisms can do many things machines cannot - they grow, they reproduce, when they reproduce their offspring vary, and they adapt on a phenotypic and genotypic level. The thing is the fact that living things can do these things makes it a certainty that evolution by natural selection will occur. It is simply a natural outcome of being able to reproduce, vary, and adapt under conditions of course where competition for resources and therefore for chances to reproduce is also inevitable. Another book you should read on this is "The Plausibility if Life" by Marc W. Kirschner and John C. Gerhart. It's really good on this machines vs life thing :)

And finally:

H. By what mechanism did non-life become life and when (roughly) did this happen?

Well as with the eye you again need to ask yourself does it make more sense for something to arise gradually by small steps or all at once? And does it make ssense for something to arise as a consequence of natural processes over a large period of time or for some "entity" to wave a magic wand or hand and hey presto! Because if you want to go down that route you then have to say where did that entity with the magic wand come from and really it gets interminably stupid. Of course I should also point out that this question is really beyond the scope of Evolutionary theory because it is a question of the origins of life and evolution itself and besides I'm sure you realise that we are talking about 3.5-4 billion or so years ago at a time when the Earth was radically different to now - no oxygen in the atmosphere, huge amounts of geothermal activity and so on. Abiogenesis (the science of life's origins) has a lot of interesting theories but nothing is that certain - how could it be? That is the cool thing about science. It's about asking the right questions and really questioning everything - not relying on faith.
Monad
 
Posts: 4
Joined: Tue Oct 10, 2006 6:58 am
Location: Leeds, UK

Previous

Return to Science Only

Who is online

Users browsing this forum: No registered users and 1 guest

cron