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Author Topic:   Definition of Species
Big_Al35
Member
Posts: 384
Joined: 06-02-2010


Message 171 of 450 (572361)
08-05-2010 11:22 AM
Reply to: Message 168 by Percy
08-05-2010 10:35 AM


Re: Species Definition
Percy writes:

Mistaking two different species for the same species happens with living creatures all the time.

Yes, and I bet it happens with extinct species even more. When you have two species that are very similar and then discover a third species which is very similar to the other two, it is easy to fall into the trap of suggesting that the new third species is a common ancestor. This may not be true at all. In the case of lions and tigers a new fossil discovery might be a lion, it might be a tiger, it might be a liger or tigon, or it might be a common ancestor. So there is infact more chance of it not being a common ancestor than of it actually being a common ancestor.

I hope you can see where I am going with this. Enjoy!


This message is a reply to:
 Message 168 by Percy, posted 08-05-2010 10:35 AM Percy has responded

Replies to this message:
 Message 174 by Percy, posted 08-05-2010 3:27 PM Big_Al35 has responded

  
Big_Al35
Member
Posts: 384
Joined: 06-02-2010


Message 177 of 450 (572473)
08-06-2010 5:20 AM
Reply to: Message 175 by RAZD
08-05-2010 9:09 PM


Re: Species Definition vs what matters (and why)
RAZD writes:

But this assumes that DNA knowledge is critical to determining different species: it isn't. It kind of seems that you want to include DNA in the definition of species, so that then you can claim that species cannot be determined without knowing the DNA. This is employing a logical fallacy in your approach.

I think it's fair to say that species cannot be determined unless you know their DNA. All the other criteria for determining species can only give best guesses. Maybe DNA is also a best guess.
Lions and tigers could be classed as the same species as they can interbreed and produce fertile female offspring. They could be classed as different species as they have different behaviour, appearance and environment. The only way to clearly identify the distinctions is to investigate the DNA. Ofcourse this doesn't mean that we shouldn't analyse the other differences aswell but DNA would spell out those differences. eg there are genes for coat colour, behaviour etc.

For extinct species we need a system too. Maybe the existing system is adequate. I don't know the details as I am not a paleontologist.


This message is a reply to:
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Replies to this message:
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 Message 203 by RAZD, posted 08-06-2010 6:59 PM Big_Al35 has responded

  
Big_Al35
Member
Posts: 384
Joined: 06-02-2010


Message 178 of 450 (572476)
08-06-2010 5:46 AM
Reply to: Message 174 by Percy
08-05-2010 3:27 PM


Re: Species Definition
Percy writes:

Yes, this is true. Because you cannot distinguish close relations from direct ancestors in the fossil record, scientists will almost never claim that some fossil species represents the common ancester for some later species.

So when I hear suggestions that fossils like 'Lucy' and others are potentially common ancestors I can promptly ignore these??


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 Message 174 by Percy, posted 08-05-2010 3:27 PM Percy has acknowledged this reply

  
Big_Al35
Member
Posts: 384
Joined: 06-02-2010


Message 180 of 450 (572480)
08-06-2010 5:59 AM
Reply to: Message 174 by Percy
08-05-2010 3:27 PM


Re: Species Definition
Percy writes:

Yes, this is true. Because you cannot distinguish close relations from direct ancestors in the fossil record, scientists will almost never claim that some fossil species represents the common ancester for some later species.

Here is a link to show that others don't share your view.


This message is a reply to:
 Message 174 by Percy, posted 08-05-2010 3:27 PM Percy has responded

Replies to this message:
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Big_Al35
Member
Posts: 384
Joined: 06-02-2010


Message 181 of 450 (572481)
08-06-2010 6:07 AM
Reply to: Message 179 by caffeine
08-06-2010 5:48 AM


Re: Species Definition
caffeine writes:

As I already pointed out upthread, this isn't true. Evidence of both scavenging and predatory behaviour has been found for tyrannosaurids, which makes sense as most carnivores do both.

Here is a link to show that your claim may be very wrong.


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Big_Al35
Member
Posts: 384
Joined: 06-02-2010


Message 186 of 450 (572489)
08-06-2010 6:58 AM
Reply to: Message 184 by Wounded King
08-06-2010 6:27 AM


Re: Species Definition vs what matters (and why)
Wounded King writes:

The problem here is not one of best guesses but, as has been suggested, of the fact that the whole idea of species is an arbitrary human construct imposed on the natural world.

This would depend on whether you believe in ID or not. Either it's a human construct or a divine construct. Our model is ofcourse the human understanding of it.

If we were talking about software we could be arguing about what makes word word and not excel. Then we would have to discuss why excel is different from lotus 123 or supercalc. Are they the same type/class? Did office 2000 evolve from office 1997. Do word and excel have a common ancestor? Answers on a postcard please.


This message is a reply to:
 Message 184 by Wounded King, posted 08-06-2010 6:27 AM Wounded King has responded

Replies to this message:
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Big_Al35
Member
Posts: 384
Joined: 06-02-2010


Message 189 of 450 (572513)
08-06-2010 8:48 AM
Reply to: Message 188 by Wounded King
08-06-2010 7:15 AM


Re: Species Definition vs what matters (and why)
Wounded King writes:

And none of this addresses the fact that since god didn't leave an FAQ behind about discerning kinds through genetics, the way to do so is far from obvious if indeed such a thing exists.

There are plenty of sites showing that DNA barcoding is well underway. Here is a link which shows that some mammals have already been barcoded, and that this is a very effective tool for species identification. I think it's just a matter of time before this becomes the standard. It's not about what I want....it's happening.

Edited by Big_Al35, : No reason given.


This message is a reply to:
 Message 188 by Wounded King, posted 08-06-2010 7:15 AM Wounded King has responded

Replies to this message:
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Big_Al35
Member
Posts: 384
Joined: 06-02-2010


Message 192 of 450 (572518)
08-06-2010 9:37 AM
Reply to: Message 190 by Percy
08-06-2010 9:17 AM


Re: Species Definition vs what matters (and why)
Percy writes:

Your objections all share something in common: they're all based upon misconstruals.

Objections!?! I don't think I have raised any objections as such....I don't disagree that locking down a species to a barcode will be an arbitrary human decision. I am confident we can get better at this over time though. These barcodes don't have to be set in stone either. Lets take the African elephant example. If the DNA barcoding was defined such that two African elephants ended up being different species I think we can rest assured that our system needs adjusting. Now if our system showed that African elephants were a different species to an Asian elephant then that would be a matter for debate.

If you are saying that experts in the field are actively advocating that Ugandan elephants are distinguished from Zambian elephants and they want them classified as different species I don't have any objection with that as such. Once the system is established and in place we can stick with it.

If anomalies rise in the future we can deal with those on an individual basis. Ofcourse there is no room for history in any of this. The fossil records and extinct animals are not part of this discussion.


This message is a reply to:
 Message 190 by Percy, posted 08-06-2010 9:17 AM Percy has responded

Replies to this message:
 Message 193 by Huntard, posted 08-06-2010 9:43 AM Big_Al35 has responded
 Message 195 by Percy, posted 08-06-2010 10:54 AM Big_Al35 has responded

  
Big_Al35
Member
Posts: 384
Joined: 06-02-2010


Message 194 of 450 (572525)
08-06-2010 10:16 AM
Reply to: Message 193 by Huntard
08-06-2010 9:43 AM


Re: Species Definition vs what matters (and why)
Huntard writes:

But we already have a system in place, why change it?

This is what my mum says to me when I tell her to switch to online shopping.


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 Message 193 by Huntard, posted 08-06-2010 9:43 AM Huntard has not yet responded

  
Big_Al35
Member
Posts: 384
Joined: 06-02-2010


Message 196 of 450 (572533)
08-06-2010 11:21 AM
Reply to: Message 195 by Percy
08-06-2010 10:54 AM


Re: Species Definition vs what matters (and why)
Really? What about this misconstrual of how much we know about T-Rex:

It's true we don't know much about TRex. 5 minutes on google will tell you that.

And what about this misconstrual of DNA's power to determine species boundaries:

If species boundaries are arbitrary they are arbitrary....what misconstrual?

And what about this objection based upon a misconstrual about scientists claims of finding common ancestors based upon an article you linked to:

I think you need to read that article again if you believe there has been a misconstrual. He clearly talks about the roots of our lineage and the earliest Homo found.


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 Message 195 by Percy, posted 08-06-2010 10:54 AM Percy has acknowledged this reply

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 Message 198 by Huntard, posted 08-06-2010 11:28 AM Big_Al35 has responded
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Big_Al35
Member
Posts: 384
Joined: 06-02-2010


Message 200 of 450 (572583)
08-06-2010 4:43 PM
Reply to: Message 198 by Huntard
08-06-2010 11:28 AM


Re: Species Definition vs what matters (and why)
Huntard writes:

Ten seconds on Google Scholar brought up 22.800 articles. Don't know much indeed.

Yeah...and they all contradict each other.


This message is a reply to:
 Message 198 by Huntard, posted 08-06-2010 11:28 AM Huntard has responded

Replies to this message:
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Big_Al35
Member
Posts: 384
Joined: 06-02-2010


Message 204 of 450 (573165)
08-10-2010 8:18 AM
Reply to: Message 203 by RAZD
08-06-2010 6:59 PM


Re: Species Definition vs what matters (and why)
RAZD writes:

Thanks for not reading 90% of my post and misconstruing the rest.

Sorry if I found 90% of your post of very little interest to the point of boredom and as for the other 10%...I wouldn't use the word misconstrue, I would use the word disagree.

RAZD writes:

Curiously, even knowing the DNA does not help, as all you are doing is adding another element to use in making a subjective determination of when arbitrary speciation occurrs -- the DNA changes by a certain amount (if you can measure it for extinct species, which makes it virtually useless for MOST species).

Again I completely disagree. Scientists have already established that DNA is virtually a language in its own right. It has the same properties including things like grammar (stop codons), meaning (genes specify certain attributes), and purpose (coding for the head, torso, legs etc). They say that large chunks of DNA are apparently meaningless but this understanding might change overtime. eg we have different fingerprints, retinas etc....this uniqueness must also be coded into the DNA with some sort of randomization mechanism (using a unique seed) built in. This in itself would require huge amounts of DNA.

DNA works effectively for determining parentage and lineage, forensic investigation into crime and is now working very well for species identification. This isn't just words...it is happening right now. DNA is not entirely arbitrary...the code for the order in which your body parts develop and the location is hard coded. Nothing arbitrary about that.

But I understand how you guys operate now. Maybe you paleontologists and biologists have livelihoods and jobs at stake. It serves your purpose to keep the rest of us in ignorance. As long as DNA is considered arbitrary and a bit of a joke you can continue your fossil finding and your species discoveries. You can make all sorts of absurd claims of finding common ancestors, missing links, new discoveries etc...then when questioned you can claim that you never meant that at all. As no DNA is available for most species that have ever walked the earth no one can ever prove you wrong....eh?

Well good luck with that!


This message is a reply to:
 Message 203 by RAZD, posted 08-06-2010 6:59 PM RAZD has responded

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 Message 209 by RAZD, posted 08-10-2010 11:02 PM Big_Al35 has responded

  
Big_Al35
Member
Posts: 384
Joined: 06-02-2010


Message 210 of 450 (574483)
08-16-2010 8:00 AM
Reply to: Message 209 by RAZD
08-10-2010 11:02 PM


Re: Species Definition vs what matters (and why)
RAZD writes:

Rather than the conspiracy theory you have just asserted, the alternative is that scientists realize the limitations of finding DNA for all the extinct species, and this is why they use alternative methods for determining hereditary traits (ie traditional morphological studies that have been used for a couple hundred years or so), and do not claim - as you seem to - that DNA is necessary to accomplish this.

Wow...great learning has made you go mad. If you continue in this vein I suspect you would eventually disappear up your own ass. I think you mean to say that scientists realize that DNA offers far more answers and solutions than are currently on offer using the alternative methods. These answers may not be what they want to hear. And anyway they don't have access to DNA from fossil evidence so this discussion is moot.


This message is a reply to:
 Message 209 by RAZD, posted 08-10-2010 11:02 PM RAZD has responded

Replies to this message:
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Big_Al35
Member
Posts: 384
Joined: 06-02-2010


Message 212 of 450 (574491)
08-16-2010 8:28 AM
Reply to: Message 208 by Wounded King
08-10-2010 4:39 PM


Re: Pushing back the boundaries of ignorance.
A stop codon is not a full stop.

I never said it was.

Total bollocks, the randomising element doesn't need to be in the DNA, it is provided by the variable nature of the environment, the stochastic nature of the physical world.

How can the variable nature of the environment affect some parts of the DNA but not the important information storing parts which spell out that we should have arms, legs, torso, head etc...I am guessing you are going to tell me now that some people are born with three legs?


This message is a reply to:
 Message 208 by Wounded King, posted 08-10-2010 4:39 PM Wounded King has responded

Replies to this message:
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 Message 215 by Dr Jack, posted 08-16-2010 9:08 AM Big_Al35 has not yet responded

  
Big_Al35
Member
Posts: 384
Joined: 06-02-2010


Message 216 of 450 (574503)
08-16-2010 9:08 AM
Reply to: Message 213 by Huntard
08-16-2010 8:45 AM


Re: Pushing back the boundaries of ignorance.
Huntard writes:

Well, there is this person:

And this one...

LOL!


This message is a reply to:
 Message 213 by Huntard, posted 08-16-2010 8:45 AM Huntard has not yet responded

  
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