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Author Topic:   Transitional forms in existence today
Percy
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Posts: 18430
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.7


Message 16 of 62 (623761)
07-13-2011 6:48 AM
Reply to: Message 12 by Portillo
07-13-2011 5:40 AM


All Species are Transitional
Portillo writes:

Lack of transitional forms today is because of "the maintenance of stability within species." Richard Dawkins says, "Evolution has been observed. Its just that it hasnt been observed while its happening."

My God, sometimes the creationist ability to confound things borders on genius.

Do you care to tell us who actually used the phrase "the maintenance of stability within species" (it wasn't Dawkins), and as a bonus question, give us the full context so we can see what was actually meant?

And what was the source and context of the Richard Dawkins' quote?

All species are transitional. Both Gould and Dawkins are aware of that and would have no reason to contradict what they believe to be true.

--Percy


This message is a reply to:
 Message 12 by Portillo, posted 07-13-2011 5:40 AM Portillo has responded

Replies to this message:
 Message 17 by Dr Jack, posted 07-13-2011 7:15 AM Percy has responded
 Message 21 by Modulous, posted 07-13-2011 9:27 AM Percy has acknowledged this reply
 Message 34 by Portillo, posted 07-14-2011 4:12 AM Percy has responded

    
Percy
Member
Posts: 18430
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.7


Message 38 of 62 (623875)
07-14-2011 7:18 AM
Reply to: Message 17 by Dr Jack
07-13-2011 7:15 AM


Re: Saying "All Species are Transitional" is equivocation
Mr Jack writes:

In general usage, when we talk about transitionals without context what we're talking are transitionals specifically between distinct higher taxonomic groups.

The OP revealed that Peter doesn't have a clear concept of what a transitional form is. He said that while he had discovered that there were transitional forms in the fossil record, he wondered why there were no transitional forms in existence today, providing as an example, "fish with half formed limbs and such." This led me to wonder what examples from the fossil record he thought were transitionals with half-formed limbs.

Later, in Message 24 he recalled reading a a creationist book that asserted there should be more species "in flux" instead of "wholly formed."

So I think what would help Peter most is an understanding that all species are always "in flux" and always "wholly formed."

The higher taxonomic groups are just accidents of evolutionary history. In a replay archeopteryx could have been representative of a major taxonomic group rather than a transitional between dinosaurs and birds. What we can point to today as representative of transitions between major taxonomic groups were not in transition any more or less than any other species at the time. I think understanding this is important.

--Percy


This message is a reply to:
 Message 17 by Dr Jack, posted 07-13-2011 7:15 AM Dr Jack has not yet responded

    
Percy
Member
Posts: 18430
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.7


Message 39 of 62 (623876)
07-14-2011 7:23 AM
Reply to: Message 34 by Portillo
07-14-2011 4:12 AM


Re: All Species are Transitional
Portillo writes:

I dont really see how humans are transitional forms. We are fully formed creatures. Yes we may be taller or something like that, but that does not mean we will evolve into something else.

All species are always in transition all the time. This is because the DNA that forms the basis of heredity is only imperfectly copied during reproduction. We are all combinations of imperfect copies of our parents' genes. The copying errors accumulate with time, even under conditions of strong selection because of neutral and nearly neutral mutations (copying errors).

The error rate when DNA is copied is very tiny, about 1 nucleotide pair in every hundred million. This is why evolutionary change tends to be slow.

--Percy


This message is a reply to:
 Message 34 by Portillo, posted 07-14-2011 4:12 AM Portillo has responded

Replies to this message:
 Message 45 by Portillo, posted 07-15-2011 3:42 AM Percy has responded

    
Percy
Member
Posts: 18430
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.7


Message 49 of 62 (623994)
07-15-2011 7:57 AM
Reply to: Message 45 by Portillo
07-15-2011 3:42 AM


Re: All Species are Transitional
Portillo writes:

I can understand the argument. But what Im saying is what exactly are humans going to evolve to, what kind of human or species?

It would be fascinating to discuss what selection pressures humans are and will be subjected to and what changes they might cause, but I think the most accurate answer would be, "We don't know."

Natural selection creates tall, short, dark skinned, white skinned humans, but that is not evolution.

But that *is* evolution. Expressed slightly more completely, you could say that evolution is natural selection operating upon inherent variation augmented by new mutations.

I think what you probably meant is that height and skin color by themselves are not sufficient evolution to create a new species, probably true under most circumstances. But the more two populations evolve separately the more different they become, and at some point their ability to interbreed declines to the point where we label them two different species.

--Percy


This message is a reply to:
 Message 45 by Portillo, posted 07-15-2011 3:42 AM Portillo has not yet responded

    
Percy
Member
Posts: 18430
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.7


Message 58 of 62 (624121)
07-16-2011 5:38 AM
Reply to: Message 56 by hooah212002
07-15-2011 3:19 PM


Re: All Species are Transitional
hooah212002 writes:

If however, some global disaster knocks us back to the stone age where our physical capabilities become more relevant than our cognitive abilities I would posit that we would evolve into something more fit for the environment.

Isn't that what it would take, given that we are able to modfy our environment to suit our needs? As opposed to the environment modifying us, which is essentially what drives evolution/NS?

The selection pressures in environments we create for ourselves are different from the selection pressures of the natural world, but there are still selection pressures. Genetic studies seem to indicate that the human race is evolving more rapidly today than at any time in our history.

This actually makes sense and is not counterintuitive. Throughout most of our evolutionary history we had limited means of controlling our environment, and the environments of civilization are much different than anything we experienced before. We think of civilization as removing selection pressures, but what has really happened is that one set of selection pressures have been replaced by another. One example is the modern innovation of gathering into large groups called cities, necessitating the evolution of more robust defenses against hostile bacteria and viruses.

--Percy


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 Message 56 by hooah212002, posted 07-15-2011 3:19 PM hooah212002 has not yet responded

    
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