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how do you get this confused???

Re: how do you get this confused???
« Reply #15 on: January 06, 2010, 02:49:31 PM »
Quote from: "mcm"
.. Do you know how complete the entire fossil record is at the moment for all species? And what are the species like at the base of the evolutionary tree and does it all go back to on specie?

Also thanks for the Wiki link, I'll have a look through it when I have some time.

You do realize that more than 99% of species that ever existed on this planet have gone extinct?  We currently have identified 2 million species on earth and scientists think there is currently AT LEAST 5 million species currently in existence ... and we make up only that 1%.  We don't need a 100% complete fossil record to make an analysis on what we find.  We have enough fossils a distinction between species based on characteristics after all many of the fossils we have are incomplete but we have multiples.   We are lucky to have as many fossils as we do since the fossilization process is rare and difficult.  However even if we didn't have a single fossil the DNA evidence we have alone is enough to prove evolution and common decent.
Quote from: "Richard Lederer"
There once was a time when all people believed in God and the church ruled. This time was called the Dark Ages

Quote from: "Demosthenes"
A man is his own easiest dupe, for what he wishes to be true he generally believes to be true.
Quote from: "Oscar Wilde"
Truth, in matters of religion, is simpl

curiosityandthecat

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Re: how do you get this confused???
« Reply #16 on: January 06, 2010, 03:53:13 PM »
[youtube:335jw20u]http://www.youtube.com/watch?v=g1lHbCyZWt4[/youtube:335jw20u]
-Curio

mcm

Re: how do you get this confused???
« Reply #17 on: January 06, 2010, 09:23:38 PM »
I do apologise for asking so many questions, I'm just trying to get a better handle on what our understanding of evolution is and where we got this understanding from and whether it makes sense.

Quote from: "LoneMateria"
You do realize that more than 99% of species that ever existed on this planet have gone extinct? We currently have identified 2 million species on earth and scientists think there is currently AT LEAST 5 million species currently in existence ... and we make up only that 1%.
I'm not so worried about numbers in terms of understanding but is interesting nevertheless. So basically you're saying we believe there to be 500 million species that have ever existed.

Quote from: "LoneMateria"
We don't need a 100% complete fossil record to make an analysis on what we find. We have enough fossils a distinction between species based on characteristics after all many of the fossils we have are incomplete but we have multiples. We are lucky to have as many fossils as we do since the fossilization process is rare and difficult. However even if we didn't have a single fossil the DNA evidence we have alone is enough to prove evolution and common decent.
What I was interested in finding out with my question is how complete is the evolutionary tree that we're constructing. Although I can understand that it is very difficult work given that all we may have to go on in some cases may just be the jaw bone and teeth. But you raise an interesting point, is much of the tree constructed from DNA analysis and so we don't know what much about what the species look like other than where it traces to in modern day species?

Quote from: "curiosityandthecat"
Evolution of Humans Animated 4 billion years in ...
Thanks curiosityandthecat, although it raises many more questions. However, is my understanding correct that we currently don't have a model of how the first DNA or cell was formed? But do we have more of an idea of what evolutionary changes are required to form the first plant? What about how bones first formed or how blood formed and organs that depend on it and how the nervous system formed and then the brain or sexual reproduction the development of the sperm and egg and how the sperm grows and forms a new animal? Also are we actually able to analyze our DNA and see that humans go back to a tree climbing mammal, to the dinosaur, and then to fish?

curiosityandthecat

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Re: how do you get this confused???
« Reply #18 on: January 06, 2010, 10:54:53 PM »
Quote from: "mcm"
Thanks curiosityandthecat, although it raises many more questions. However, is my understanding correct that we currently don't have a model of how the first DNA or cell was formed? But do we have more of an idea of what evolutionary changes are required to form the first plant? What about how bones first formed or how blood formed and organs that depend on it and how the nervous system formed and then the brain or sexual reproduction the development of the sperm and egg and how the sperm grows and forms a new animal? Also are we actually able to analyze our DNA and see that humans go back to a tree climbing mammal, to the dinosaur, and then to fish?
I'm not an evolutionary biologist, sadly.  :raised: In fact, the eye has evolved from cells that, through billions of iterations and mutations, happened to be sensitive to light (photosensitive). Think about this... you're a simple organism that is often eaten by other, larger simple organisms. By luck, you happen to have a collection of cells somewhere on your body that are photosensitive. That larger organism comes near you, change ambient light conditions, those cells "activate" and you move out of the way (probably due to fright more than a learned response). Voila, you've avoided being eaten. Your neighbor, however, who does not have that mutation, is promptly gobbled up. Score one for photosensitivity and pass those genes down. Again. And again. And again. And as has been said before, if it's between being eaten and living, half an eye is better than no eye at all.

Of course, build a better mouse trap and nature builds a better mouse, right? The larger organisms evolve to better chase you down, but, ah, one of your great-great-great-great-great-great-grandchildren has even better photosensitivity and, whoa, this time it detects motion! And the process repeats.

That's all evolution is: better mice and better mousetraps, forever going round and round. But these are not clear-cut steps. Think of it like baking bread: there's the time when it's dough and the time when it's bread, but in evolution's case the time in between is millions of years. Trying to find the point at which these changes occur is really a wild goose chase. Our minds are wired to think in time scales like that.

Here's a college textbook on evolutionary biology. Maybe others can provide better resources, I dunno.
-Curio

Re: how do you get this confused???
« Reply #19 on: January 07, 2010, 12:11:46 AM »
Quote from: "mcm"
I'm not so worried about numbers in terms of understanding but is interesting nevertheless. So basically you're saying we believe there to be 500 million species that have ever existed.

At the very, very, very minimum yes.  Sadly the estimate is much much wider then that.  The general estimate on the number of species currently in existence ranges from the extreme conservative number of 5 million up to the monster number of 100 million (very wide range I know).  Also (just to clarify) I used 99% because it was just easier to put.  If I remember correctly the generally accepted number is 99.5% to 99.8% (If I remember correctly).  I was just using 99% because I wasn't certain of the number.  Anyway the number of potential species that existed throughout the earths history is a very wide range.  


Quote from: "mcm"
What I was interested in finding out with my question is how complete is the evolutionary tree that we're constructing. Although I can understand that it is very difficult work given that all we may have to go on in some cases may just be the jaw bone and teeth. But you raise an interesting point, is much of the tree constructed from DNA analysis and so we don't know what much about what the species look like other than where it traces to in modern day species?

It's largely incomplete.  When you look at the huge tree you are seeing what we've found in the fossil record and the current linage we've found through DNA evidence.  It is not typically showing the species that have died out.  There will be species we will never learn about since they died off completely without any of it's members being preserved by fossilization.  Realistically the tree they are trying to construct won't be able to house the Billions of species that have existed.  We can try and get a good linage but you are talking about trying to reconstruct a family tree hundreds of millions (if not billions) of years after the fact.  It's a noble effort and the tree will be very impressive, however it will be largely incomplete.
Quote from: "Richard Lederer"
There once was a time when all people believed in God and the church ruled. This time was called the Dark Ages

Quote from: "Demosthenes"
A man is his own easiest dupe, for what he wishes to be true he generally believes to be true.
Quote from: "Oscar Wilde"
Truth, in matters of religion, is simpl

Squid

Re: how do you get this confused???
« Reply #20 on: January 07, 2010, 02:09:23 AM »
Quote from: "mcm"
Quote from: "Squid"
Some scientists have played around with non-coding regions and produced some interesting changes - such as inducing the growth of Archosaurian teeth in a chicken back in 2006 further supporting relationship between birds and archosaurs.
Interesting, do you know of any online articles about this where I can find out more info?

Here's the article from Current Biology:

Chicken Teeth

And about the dino/bird connection, here's the wiki that's not too bad:

http://en.wikipedia.org/wiki/Origin_of_birds

Quote
Do you know how complete the entire fossil record is at the moment for all species? And what are the species like at the base of the evolutionary tree and does it all go back to on specie?

Do you mean, how many specimens do we have that represent all the species that have lived on Earth?  Well, the world's collection of specimens is pretty vast but it's just a small fraction of what has most likely existed and it keeps growing all the time.  The most notable are those which has exceptional preservation like the discovery of the Burgess Shale.  The oldest recognized fossils are ancient stromatolites.  Hope this helps a bit, sorry I didn't have time to really get to in depth.

mcm

Re: how do you get this confused???
« Reply #21 on: January 08, 2010, 04:30:38 AM »
Thanks curiosityandthecat for sharing what you know about evolution of the cell and what you know about DNA / RNA. I can see what you are getting at with the eye, that something may evolve that serves one purpose and continues to evolve to serve an entirely different purpose. I guess what I would be interested in is a step by step breakdown of each part of they eye and how they each evolved and came together into what we have today. Of course to get a better understanding of all this it's probably about time I learnt basic things like the structure of the cell and how proteins work and how different tissue forms and so on. Obviously you need to know how they work to properly understand how they could have evolved.

Quote from: "curiosityandthecat"
Anyway, it's important to remember that it didn't go nothing --> full-on sperm/egg sexual reproduction. Millions and millions of years separate the two.
I guess what I was trying to reconcile is how reproduction would have worked as sexual reproduction evolved and what were the environmental conditions that reinforced that evolutionary path of sexual reproduction. Also are there any creatures that are alive today that can reproduce in two different ways like there are some fish who can both swim and crawl on land.

Quote from: "LoneMateria"
At the very, very, very minimum yes. Sadly the estimate is much much wider then that. The general estimate on the number of species currently in existence ranges from the extreme conservative number of 5 million up to the monster number of 100 million (very wide range I know). Also (just to clarify) I used 99% because it was just easier to put. If I remember correctly the generally accepted number is 99.5% to 99.8% (If I remember correctly). I was just using 99% because I wasn't certain of the number. Anyway the number of potential species that existed throughout the earths history is a very wide range.
That's cool a large number in other words (I find it hard to visualize 1 million let alone a bigger number anyway). It does beg the question how different do two different animals need to be before they are classified as different species. Is it kind of like two different butterflies can physically mate and produce offspring but because of different colouration they are never attracted to one another and never mate in practice so are therefore considered as two different species?

Quote from: "LoneMateria"
It's largely incomplete. When you look at the huge tree you are seeing what we've found in the fossil record and the current linage we've found through DNA evidence. It is not typically showing the species that have died out. There will be species we will never learn about since they died off completely without any of it's members being preserved by fossilization. Realistically the tree they are trying to construct won't be able to house the Billions of species that have existed. We can try and get a good linage but you are talking about trying to reconstruct a family tree hundreds of millions (if not billions) of years after the fact. It's a noble effort and the tree will be very impressive, however it will be largely incomplete.
Quote from: "Squid"
Do you mean, how many specimens do we have that represent all the species that have lived on Earth? Well, the world's collection of specimens is pretty vast but it's just a small fraction of what has most likely existed and it keeps growing all the time. The most notable are those which has exceptional preservation like the discovery of the Burgess Shale. The oldest recognized fossils are ancient stromatolites. Hope this helps a bit, sorry I didn't have time to really get to in depth.
Thanks that answers one of the questions I had.

curiosityandthecat

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Re: how do you get this confused???
« Reply #22 on: January 08, 2010, 04:48:42 PM »
Quote from: "mcm"
I guess what I was trying to reconcile is how reproduction would have worked as sexual reproduction evolved and what were the environmental conditions that reinforced that evolutionary path of sexual reproduction. Also are there any creatures that are alive today that can reproduce in two different ways like there are some fish who can both swim and crawl on land.
If you can think of it, there's something out there that does it. ;) Look up Rotifers. Neat little guys. Or, girls, rather. I guess. Not only is it possible for an organism to reproduce both sexually and asexually, some animals will switch their biologic sex. Neat, huh?
-Curio

mcm

Re: how do you get this confused???
« Reply #23 on: January 09, 2010, 12:01:37 PM »
Quote from: "curiosityandthecat"
If you can think of it, there's something out there that does it. ;) Look up Rotifers. Neat little guys. Or, girls, rather. I guess. Not only is it possible for an organism to reproduce both sexually and asexually, some animals will switch their biologic sex. Neat, huh?
Thanks for your answer, it does help.

Re: how do you get this confused???
« Reply #24 on: January 09, 2010, 04:21:29 PM »
Quote from: "mcm"
That's cool a large number in other words (I find it hard to visualize 1 million let alone a bigger number anyway). It does beg the question how different do two different animals need to be before they are classified as different species. Is it kind of like two different butterflies can physically mate and produce offspring but because of different colouration they are never attracted to one another and never mate in practice so are therefore considered as two different species?

Thats a good question.  Honestly I don't know.  I thought it was when they could no longer mate with other species but I know thats wrong.
Quote from: "Richard Lederer"
There once was a time when all people believed in God and the church ruled. This time was called the Dark Ages

Quote from: "Demosthenes"
A man is his own easiest dupe, for what he wishes to be true he generally believes to be true.
Quote from: "Oscar Wilde"
Truth, in matters of religion, is simpl

Squid

Re: how do you get this confused???
« Reply #25 on: January 10, 2010, 12:19:19 AM »
Quote from: "LoneMateria"
Quote from: "mcm"
That's cool a large number in other words (I find it hard to visualize 1 million let alone a bigger number anyway). It does beg the question how different do two different animals need to be before they are classified as different species. Is it kind of like two different butterflies can physically mate and produce offspring but because of different colouration they are never attracted to one another and never mate in practice so are therefore considered as two different species?

Thats a good question.  Honestly I don't know.  I thought it was when they could no longer mate with other species but I know thats wrong.

The biological species concept:

http://www.blackwellpublishing.com/ridley/a-z/Biological_species_concept.asp

Re: how do you get this confused???
« Reply #26 on: February 16, 2010, 01:53:28 PM »
let richard explain it...Evolution of the eye

http://www.youtube.com/watch?v=No7UCB2meF0