>What we observe is an increase in complexity among
>a certain lineage in the fossil record.
Glenn:
>Thank you, you have acknowledged that complexity has increased throughout
>geologic time. It was difficult to get you to acknowledge this, but this
>will do.
I'm happy to clear that up, although I did not realize you were
trying to get me to "acknowledge" complexity has increased
throughout geologic time. All I did was to point out:
"That depends entirely on the chosen perspective. For example, *among*
porifera, has there been an increase in complexity in the last 570 million
years? Among arthropods, has there been an increase in complexity in
the last 530 million years? Etc. [Also, don't forget to change the date of
agnatha in light of the recent fossil finds]."
My interest is not in some irrational denial of increasing complexity
among certain lineages over time. My interest is that this increase
appears to have happened against a backdrop where evolution doesn't
typically do this.
Me:
>Let me try to explain. Yes, we seem to see an increase in complexity
>*among vertebrates*, going from 64 to 210 cell types. Yet let's put
>this indirect observation in its CONTEXT. Do we see similar increases
>in other phyla or classes? No.
Glenn:
>I wouldn't yet say that we don't.
Okay, let me rephrase it then. I know of no evidence that shows the
type of increased complexity seen among vertebrates is typical
and characteristic of evolution.
>I haven't posted a list of various arthropods and neither have you. YOu
>say I am answering Art with philosophy, what do you call your answer
>here. There is no documentation whatsoever to back up your assertion
>that there has been no increase in cell types among the arthropods. While
>I don't know if they have or haven't, I know this, we can't decide that
>question by opinion, either yours or mine. Data is what is required and
>you haven't presented any.
I'm just taking your cited paper seriously. Remember the list you
cited?
>Porifera 10 cell types 570 myr
>Cnidaria 14 cell types 560 myr
>Haemocoelic Bilaterian 30 cell types 560 myr
>Arthropoda 51 cell types 530 myr
>Echinodermata, Annelids 39 cell types 525 myr
>Agnatha 64 cell types 510 myr
>Cephalopoda 75 cell types 500 myr
>Actinopterygii 132 cell types 400 myr
>Amphibia 150 cell types 330 myr
>Diapsida 154 cell types 300 myr
>Aves 187 cell types 150 myr
>Hominidae 210 cell types 5 myr
Perhaps this paper is flawed and there is no basis for
saying phylum Arthropoda is characterized by 51 cell
types. But one would think we could interpret the scientific
literature literally.
Of course, would it really surprise you to find that cell type
numbers have not increased except among vertebrates? Does
the fossil record show increasing complexity among
porifera, annelids, arthropods, and cnidarians?
Me:
>Thus, the
>overall, general pattern of evolution has not been towards increasing
>complexity
>via increasing cell type numbers. This is the way evolution typically works.
>And this would explain all the lab data which (AFAIK) has not detected
>any new cell types as a consequence of the vast number of mutants that
>have been analyzed. Yet it is within this overall context where we find this
>exception of the lamprey-fish-amphibian-reptile-bird/mammal
>transition. To me, this clearly suggests there is something special about
>this transitional series.
Glenn:
>I don't disagree that there is something special about the line that lead
>to us. I believe that God created the biosystems with us in mind and thus
>rigged the dice of the universe in order to bring us about. That being
>said, that doesn't rule out an increase in maximum complexity throughout
>time. If God designed the universe is the fashion described above, we would
>expect some lineage to lead to us.
And I agree with all this. The question seems to be one of timing - just
when were the dice loaded and how often? Now, I don't claim to know.
But there does seem to be some suggestive data that causes me to
suspect dice were loaded more recently than the origin of the
universe.
Me:
>Let's use your lottery example to demonstrate this. Say we institute a
>national lottery. You win the lottery (lucky you!). Now, let's say the
>lottery is played every week for every year until the year 3000. Since
>the odds against winning are very low, there are only a total of 100
>winners during this new millenium. Yet every one of those winners
>is one of your descendents. How would you interpret this?
Glenn:
>You forget something here. The specialness can not apply to the original
>chordate progenitor. If it hadn't been them, it would have been some other
>group we were ascribing things to.
No, if it hadn't been for them, there wouldn't be anyone to do any
ascribing.
>There had to be an ancestor for whoever lives today. And whatever form
>intelligent life took, it would view its ancestor as special. One can only
find
>retrodicted specialness by looking backwards.
I would personally find your point more meaningful if we lived on a
planet where we traded and formed treaties with a species of mollusc,
annelid, and perhaps even a multicellular prokaryote. But while
evolution was busying evolving complexity among verterbrates,
just about everything else remained much the same.
>In your analogy, if my great great great grandson looked back
>and saw that everyone of his ancestors won the lottery then he would have
>some reason to believe his was a special lineage. In 5000 years, when my
>genes are spread quite widely around the world, for one of my descendants
>to win the lottery will not be very special because I will have maybe
>millions of descendants.
But there are no (or only very few) winners of the complexity
prize apart from the vertebrates. That's the point. What made
the vertebrates so much more lucky than any other phylum?
>Thus, your way of looking at this is wrong. Looking from now to the past,
>we find that birds are not on our evolutionary lineage, yet Aves was
>clearly a winner in this case. Marsupials are not on our lineage, yet they
>also would rank high in the number of cellular types. Actinopterygii also
>are not on our lineage. We are descended from the Sarcopterygii, an
>equivalent subclass according to Carrol, Vertebrate Paleontology and
>Evolution, p. 611. And the Diapsids are not on our lineage. Thus from the
>chart I posted, the only direct lineage is agnatha (64)-> Amphibia (150)->
>Hominidae (210). The rest of what you had isn't on the lineage.
What I "had" is simply what I copied from you. You originally
noted:
>Thus evolution has increased the number of
>cellular types by evolving worms into chordates, chordates into fish, fish
>into amphibia, amphibia into reptiles and reptiles into mammals and birds.
>So, the answer to your question, like Mike's is that evolution has been
>busy turning worms into men.
Now, you seem to be misinterpreting my point. I am not arguing that
the very lineage which gave rise to human beings is special. I am
suggesting the vertebrates are special in that they have shown a
potential for dramatic increases in complexity not seen in any other
phylum. Thus, your point, " There had to be an ancestor for whoever
lives today. And whatever form intelligent life took, it would view its
ancestor as special," doesn't apply to the point I am exploring. Yet,
there is still the gnawing problem that even among the vertebrates,
dramatic increases in complexity are not typical (how many species
of fish have evolved throughout the last 500 million years that
did not inhabit the land?). Apparently then, the route to human beings
was atypical.
Mike