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PhilP
6th October 2006 - 01:19 AM
According to evolutionary theories, living things continued to reproduce as they became ever more complex. At some stage, though, the female of a number of species had to develop reproductive cells requiring fertilization by a male with complementary reproductive cells. In order to supply the proper number of chromosomes to the offspring, each parent's reproductive cells undergo a remarkable process called meiosis, whereby cells from each parent are left with half the usual number of chromosomes. This process prevents the offspring from having too many chromosomes.

Of course, the same process would have been needed for other species. How, then, did the "first mother" of each species become capable of reproducing with a fully developed "first father"? How could both of them have suddenly been able to halve the number of chromosomes in their reproductive cells in the manner needed to produce a healthy offspring with some characteristics of both parents? And if these reproductive features developed gradually, how would the male and female of each species have survived while such vital features were still only partially formed?

In even a single species, the odds against this reproductive interdependence coming about by chance are beyond measuring. The chance that it arose in one species after another defies reasonable explanation. Can a theoretical process of evolution explain such complexity? How could accidental, random, purposeless events result in such intricately interrelated systems? Living things are full of characteristics that show evidence of foresight and planning—pointing to an intelligent Planner. -Awake!
rpenner
6th October 2006 - 03:22 AM
QUOTE (PhilP+Oct 6 2006, 01:19 AM)
According to evolutionary theories, living things continued to reproduce as they became ever more complex.
It sounds like you are equating "more evolved" as more complex, which is not implicit in the theory of common descent with modification. Nematodes are in many senses at least as "evolved" as human beings, having probably more generations since the common ancestor of man and roundworms, so complexity is not inherent in evolution. The smallest nematodes, however, are marvels of efficiency, with every cell of their structure numbered and studied. Even human beings are in some sense evolutionarily degenerate -- because our ancestors had a lot of fruit in their diet, evolution had no strong pressure to keep a Vitamin C synthesis pathway -- less complex than a hypothetical human without the need for a diet rich in Vitamin C.
But you are right in that Evolution needs reproduction to proceed (it's implicit in that common descent term) -- but you neglect non-sexual means of reproduction.
QUOTE (PhilP+Oct 6 2006, 01:19 AM)
At some stage, though, the female of a number of species had to develop reproductive cells requiring fertilization by a male with complementary reproductive cells.
Actually, like the vertebrate eye, sexual reproduction is a mechanism that only needs to arise once in evolution. The wildly different non-vertebrate eyes show that eyes can independently arise, and the same is true of sex. In bacteria, sex involves exchanges of plasmids, and isn't tied to the reproduction of the cell itself. So let's define sexual reproduction so that we'll know it when we see it.
QUOTE
  1. production of haploid gametes by meiosis, a reduction division, and
  2. fusion of these gametes produces a zygote and restores the full diploid complement of chromosomes.

Fusion probably evolved first, as a DNA repair mechanism. Even bacteria have fusion and they use it in their form of sex.
All modern eukaryotes share a meiosis with characteristics that make it plausible that sex as we know it evolved 1-2 billion years ago.
In The Evolution of Sex, by J. Maynard-Smith (1978), the following hypothetical scenario of evolutionary milestones is given:
QUOTE (->
QUOTE
  1. production of haploid gametes by meiosis, a reduction division, and
  2. fusion of these gametes produces a zygote and restores the full diploid complement of chromosomes.

Fusion probably evolved first, as a DNA repair mechanism. Even bacteria have fusion and they use it in their form of sex.
All modern eukaryotes share a meiosis with characteristics that make it plausible that sex as we know it evolved 1-2 billion years ago.
In The Evolution of Sex, by J. Maynard-Smith (1978), the following hypothetical scenario of evolutionary milestones is given:
  1. Binary cell fusion (advantage ~ hybrid vigor; masking deleterious mutations)
  2. Evolve the use of one spindle apparatus (advantage = maintaining both sets of chromosomes and hence any hybrid vigor effects
  3. Homologous pairing and chiasma (next step but advantage unclear; generates variation but also creates regions of genetic homozygosity)
  4. Reduction division + syngamy (favored to restore heterozygosity)

All Eukaryotes have these processes, but slime molds and flowering plants and man put the elements together in different ways.
QUOTE (PhilP+Oct 6 2006, 01:19 AM)
In order to supply the proper number of chromosomes to the offspring, each parent's reproductive cells undergo a remarkable process called meiosis, whereby cells from each parent are left with half the usual number of chromosomes. This process prevents the offspring from having too many chromosomes.
In slime molds, a counter example to your zygote-bias is found. Haploids have a life, too. Indeed, from a mechanical point of view, your doubled-up chromosomes mark you as a fusion of redundant DNA sets.
QUOTE (PhilP+Oct 6 2006, 01:19 AM)
Of course, the same process would have been needed for other species. How, then, did the "first mother" of each species become capable of reproducing with a fully developed "first father"? How could both of them have suddenly been able to halve the number of chromosomes in their reproductive cells in the manner needed to produce a healthy offspring with some characteristics of both parents?
By the time you ask your question you have conflated your world views, without a special creation, only evolution exists, and if only evolution exists, then sex only has to arise once by a common ancestor.
QUOTE (PhilP+Oct 6 2006, 01:19 AM)
And if these reproductive features developed gradually, how would the male and female of each species have survived while such vital features were still only partially formed?
Based on the same combination of special creation of nearly complete individuals followed by evolution.
QUOTE (PhilP+Oct 6 2006, 01:19 AM)
In even a single species, the odds against this reproductive interdependence coming about by chance are beyond measuring. The chance that it arose in one species after another defies reasonable explanation. Can a theoretical process of evolution explain such complexity?
Actually, each of the 4 steps above is plausible evolvable in early eukaryotes, with the specific advantages of each feature listed. One line of reasoning of this makes your implausible line of reasoning 1) meaningless and 2) ignorant.
QUOTE (PhilP+Oct 6 2006, 01:19 AM)
How could accidental, random, purposeless events result in such intricately interrelated systems?
Only if each stage of the evolution of sex had immediate benefits to the populations at the time. Populations evolve, not individuals. Plenty of complex systems show evidence of co-evolution, different parts evolving without a grand plan.
QUOTE (PhilP+Oct 6 2006, 01:19 AM)
Living things are full of characteristics that show evidence of foresight and planning—pointing to an intelligent Planner. -Awake!
Unless no intelligence is required for the natural evolution of the examples you give, in which case you have no evidence.

http://biomed.brown.edu/Courses/BIO48/19.Evol.of.Sex.HTML
http://www.talkorigins.org/indexcc/CB/CB350.html
http://www.talkorigins.org/indexcc/CB/CB610.html

Barton, N. H. and B. Charlesworth, 1998. "Why sex and recombination?" Science 281: 1986-1990.
Davies, E. K., A. D. Peters and P. D. Keightley, 1999. "High frequency of cryptic deleterious mutations in Caenorhabditis elegans." Science 285: 1748-1751.
Kondrashov, Alexey S., 1997. "Evolutionary genetics of life cycles." Annual Review of Ecology and Systematics 28: 391-435.
Sá Martins, J. S., 2000. "Simulated coevolution in a mutating ecology." Physical Review E 61(3): R2212-R2215.
Judson, Olivia, 2002. Dr. Tatiana's Sex Advice to All Creation, New York: Metropolitan Books.
Margulis, Lynn and Dorion Sagan, 1990. Origins of sex: three billion years of genetic recombination, New Haven: Yale University Press.
Wuethrich, Bernice, 1998. "Why sex? Putting theory to the test." Science 281: 1980-1982.
See also several related articles in the same issue.
Schilthuizen, Menno. 2001. Frogs, Flies, and Dandelions: the making of species, Oxford Univ. Press.
Dieckmann, Ulf and Michael Doebeli. 1999. "On the origin of species by sympatric speciation." Nature 400: 354-357.
Kondrashov, Alexey S. and Fyodor A. Kondrashov. 1999. "Interactions among quantitative traits in the course of sympatric speciation." Nature 400: 351-354.
Otte, D. and J. A. Endler, eds. 1989. Speciation and Its Consequences. Sunderland, MA: Sinauer Assoc.

Also:
QUOTE
The variety of life cycles is very great. It is not simply a matter of being sexual or asexual. There are many intermediate stages. A gradual origin, with each step favored by natural selection, is possible (Kondrashov 1997). The earliest steps involve single-celled organisms exchanging genetic information; they need not be distinct sexes. Males and females most emphatically would not evolve independently. Sex, by definition, depends on both male and female acting together. As sex evolved, there would have been some incompatibilities causing sterility (just as there are today), but these would affect individuals, not whole populations, and the genes that cause such incompatibility would rapidly be selected against.


Many hypotheses have been proposed for the evolutionary advantage of sex (Barton and Charlesworth 1998). There is good experimental support for some of these, including resistance to deleterious mutation load (Davies et al. 1999) and more rapid adaptation in a rapidly changing environment, especially to acquire resistance to parasites (Sá Martins 2000).
PhilP
6th October 2006 - 11:59 AM
rpenner, I see your "arguments" (?) are rife with theories, postulation, assertion dogma, and contradiction. You sound like someone who's lost the plot. Your arguments lend more weight to Creation than anything else.
QUOTE
QUOTE (PhilP @ Oct 6 2006, 01:19 AM)
And if these reproductive features developed gradually, how would the male and female of each species have survived while such vital features were still only partially formed?

Based on the same combination of special creation of nearly complete individuals followed by evolution.

Here you argue for Creation, followed by evolution. Well, they are not exactly compatible notions are they.
QUOTE (->
QUOTE
QUOTE (PhilP @ Oct 6 2006, 01:19 AM)
And if these reproductive features developed gradually, how would the male and female of each species have survived while such vital features were still only partially formed?

Based on the same combination of special creation of nearly complete individuals followed by evolution.

Here you argue for Creation, followed by evolution. Well, they are not exactly compatible notions are they.
The smallest nematodes, however, are marvels of efficiency, with every cell of their structure numbered and studied. Even human beings are in some sense evolutionarily degenerate --

My points exactly. There's no such thing as "simple" life forms which we supposedly sprang from. Yes, humans are degenerating due to imperfection. But if we evolving we should be ridding ourselves of all weaknesses, and be living hundreds of years by now. Even a tortoise can live 175 years. BTW we are biologically closer to mice than monkeys, however some prefer to identify with the latter.
rpenner
6th October 2006 - 06:16 PM
QUOTE (PhilP+Oct 6 2006, 11:59 AM)
rpenner, I see your "arguments" (?) are rife with theories, postulation, assertion dogma, and contradiction. You sound like someone who's lost the plot. Your arguments lend more weight to Creation than anything else.
Judge not, lest you be judged. I love how I have actual biologists backing up my every statement and when you are called on falsely equating evolution as progress towards complexity you simply ignore the correction. None of the postulates are mine, all have been published -- I cited the books and articles. Did you mean to put a comma between assertion and dogma -- I don't know what "assertion dogma" is? How can I be dogmatic if all my views are based on physical evidence -- if you show me physical evidence that would be a step to changing my views. I don't think I contradicted myself anywhere.

QUOTE (PhilP+Oct 6 2006, 11:59 AM)
QUOTE (rpenner+Oct 6 2006, 03:22 AM)
QUOTE (PhilP+Oct 6 2006, 01:19 AM)
Of course, the same process would have been needed for other species. How, then, did the "first mother" of each species become capable of reproducing with a fully developed "first father"? How could both of them have suddenly been able to halve the number of chromosomes in their reproductive cells in the manner needed to produce a healthy offspring with some characteristics of both parents?
By the time you ask your question you have conflated your world views, without a special creation, only evolution exists, and if only evolution exists, then sex only has to arise once by a common ancestor.
QUOTE (PhilP+Oct 6 2006, 01:19 AM)
And if these reproductive features developed gradually, how would the male and female of each species have survived while such vital features were still only partially formed?
Based on the same combination of special creation of nearly complete individuals followed by evolution.
Here you argue for Creation, followed by evolution. Well, they are not exactly compatible notions are they.
Any fair reader would have seen that I was objecting to your assumptions implicit in the question, as in "Why did you go to the supermarket after beating your wife?" If you answer such a question, you appear to agree to the assumptions make by the asker. I have restored the context.

http://www.cuyamaca.edu/bruce.thompson/Fallacies/complex.asp

While scientists are interested in finding the truth and apologists are interested in supporting a view as if it were the truth, Tomas Aquinas wouldn't have broken the rules of discourse just to make a point. In his view, it wouldn't be "Christian."

QUOTE (PhilP+Oct 6 2006, 11:59 AM)
QUOTE (rpenner+Oct 6 2006, 03:22 AM)
QUOTE (PhilP+Oct 6 2006, 01:19 AM)
According to evolutionary theories, living things continued to reproduce as they became ever more complex.
... Nematodes are in many senses at least as "evolved" as human beings, having probably more generations since the common ancestor of man and roundworms, so complexity is not inherent in evolution. The smallest nematodes, however, are marvels of efficiency, with every cell of their structure numbered and studied. Even human beings are in some sense evolutionarily degenerate --...
My points exactly. There's no such thing as "simple" life forms which we supposedly sprang from.
Actually, I think that your thinking about "simple" is rooted in some engineering courses and not biology. Define the word "simple" and I will point out an ancestor who was simpler. But evolution is not defined as progress from simple to complex.
http://www.talkorigins.org/faqs/homs/
QUOTE (PhilP+Oct 6 2006, 11:59 AM)
Yes, humans are degenerating due to imperfection.

Was Einstein more degenerate than Attila the Hun? You have a narrow view of life on Earth, please support it with citations.
http://www.talkorigins.org/indexcc/CH/CH320.html
QUOTE (PhilP+Oct 6 2006, 11:59 AM)
But if we evolving we should be ridding ourselves of all weaknesses, and be living hundreds of years by now. Even a tortoise can live 175 years.
Evolution is not about the individual but the population. Evolution works by natural selection for differential reproductive success. Since women have menopause near age 40, there is not much evolutional pressure to live longer than that. Evolution pressures the old to die so that the population isn't held back by them. So your assertion that evolution predicts long(er) life is not based on evidence or a consistent line of reasoning.
QUOTE (PhilP+Oct 6 2006, 11:59 AM)
BTW we are biologically closer to mice than monkeys, however some prefer to identify with the latter.
This is only true if you compare two numeric studies of closeness which have no relation to each other. Also, shouldn't you be talking about apes, not monkeys?
http://www.talkorigins.org/faqs/molgen/
http://www.talkorigins.org/indexcc/CB/CB144.html
PhilP
7th October 2006 - 08:39 AM
rpenner, thank-you for your further comment. It seems I missed a lot of your initial post when reading it as it wasn't listed in my browser for some reason, but I'll try to respond further soon.
El_Machinae
8th October 2006 - 12:53 AM
Again, sexual reproduction was invented before all the 'big' species were. It's not like rabbits and lizards independantly invented sexual reproduction; their ancestor did.
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