Monday, September 19, 2005

QUOTES, READINGS, and EXPERTS: Evolution from Prokaryotes to Eukaryotes

QUOTES
from an Evolutionary perspective:

Note by KW: There is no fossil record documenting the evolution of the eukaryotes. This means that the ideas about their evolution have been inferred as speculations formed from a study of the biology of modern organisms.

"We have made a number of general and specific statements about the nature and direction of coevolution in bacteria and their viruses and plasmids...Most of these statements about how things came to be are no more than microbial Just So Stories. As is the case with other evolutionary phenomena, there is no way to formally demonstrate that the suggested pathways are indeed the actual ways things came to be". (Coevolution in bacteria and their viruses and plasmids, in Coevolution 99, pg. 126-27 (Douglas Futuyma and M. Slatkin, eds. 1983)

"The differences in the biochemistry of messenger RNA formation in eukaryotes compared to prokaryotes are so profound as to suggest that sequential prokaryotic to eukaryotic cell evolution seems unlikely. The recently discovered noncontiguous sequences in eukaryotic DNA that encode messenger RNA may reflect an ancient, rather than a new, distribution of information in DNA and that eukaryotes evolved independently of prokaryotes". (Darnell, Implications of RNA-RNA Splicing in Evolution of Eukaryotic Cells, 202 Science 1257 (1978)

"We know the overall sequence of life's origin, from CHONSP (carbon, hydrogen, oxygen, nitrogen, sulfur, phosphorus), to monomers, to polymers, to cells; we know that the origin of life was early, microbial, and unicellular; and we know that an RNA world preceded today's DNA-protein world. We do not know the precise environments of the early earth in which these events occurred; we do not know the exact chemistry of some of the important chemical reactions that led to life; and we do not have any knowledge of life in a pre-RNA world." As for what we have failed to consider, Schopf suggested that the "'pull of the present' makes it extremely difficult for us to model the early earth's atmosphere and the biochemistry of early life." (UCLA Paleobiologist William Schopf, quoted from The Woodstock of Evolution, Scientific American, June 27, 2005).

(NOTE by KW: These are the kind of statements that evolutionists make all the time, basically saying "we know that evolution happened, we just don't know how". Most people with any common sense understand this to be a 'cart before the horse' type of remark that anyone with an ounce of common sense can understand. Such remarks simply do not fly with any educated person, unless they are pre-disposed to accept evolution. That evolutionists continue making such statements, while at the same time insisting that evolution is the only acceptable explanation for the origin and development of life, indicates that they have yet to learn that it is precisely statements like this that convince the rest of the planet that evolution is just pure speculation, and is not worthy of being regarded as the sole alternative)

"One of the most difficult stages to be explained in evolution is to scientifically explain how organelles and complex cells developed from these primitive creatures [bacterial cells]. No transitional form has been found between these two forms. One and multicelled creatures carry all this complicated structure, and no creature or group has yet been found with organelles of a simpler construction in any way, or which are more primitive. In other words, the organelles carried forward have developed just as they are. They have no simple and primitive forms...Complex cells never developed from primitive cells by a process of evolution." (Kalitim ve Evrim (Inheritance and Evolution), by Dr. Ali Demirsoy, Ankara, Meteksan Yayýnlarý, 1984, p. 79. NOTE: Dr. Demirsoy is an evolutionist...)

"The gap between eukaryotes, cells with nuclei, and prokaryotes, cells which lack nuclei, is considered by many biologists to be the most profound missing link in evolutionary history."
(The Serial Endosymbiosis Theory of Eukaryotic Evolution, by Jeremy Mohn.)

from an Intelligent Design perspective:



READINGS
from an Evolutionary perspective:


"Eukaryotes must have arisen from prokaryotic ancestors. Many aspects of this are still unknown, but there is persuasive evidence that the mitochondria and plastids (chloroplasts) of today’s eukaryotes are derived from prokaryotes. For example, both mitochondria and plastids have a single circle of DNA (the vestige of a bacterial chromosome) which codes for some of their functions. Also, mitochondria and plastids have ribosomes that resemble those of prokaryotes (termed 70S ribosomes) and that are sensitive to antibacterial antibiotics. Gene sequencing shows that:
  • the mitochondrial genome almost certainly arose from a purple bacterium
  • the plastid genome almost certainly arose from a cyanobacterium.

Thus, it is believed that these organelles of eukaryotes represent bacteria that once lived inside the cells of other bacteria. Over evolutionary time, the endosymbionts (ntermal dwellers) lost the ability for an independent life and became reduced to the state of serving particular functions (oxidative energy metabolism, and photosynthesis) in eukaryotes.

It is much more difficult to trace the origins of two other characteristic features of eukaryotes - the nucleus and the cytoskeleton (which is composed or microtubules and associated proteins)


The Microbial World,
produced by Jim Deacon
Institute of Cell and Molecular Biology
The University of Edinburgh.

Tree of Life Web Project: Eukaryotes
Patterson, David J and Sogin, Mitchell L.
The Josephine Bay Paul Center in Comparative Molecular Biology and Evolution
Marine Biological Laboratory
7 MBL Street
Woods Hole, Massachusetts 02543

Creatures from the Black Lagoon: Lessons in the Diversity and Evolution of Eukaryotes, by Scott Dawson.

from an Intelligent Design perspective:


xxx


EXPERTS

Evolution

DOOLITTLE, Russell F. - Professor of molecular biology at the University of California, San Diego.

KEELING
, Dr. Patrick - Canadian Institute for Advanced Research scholar at the University of British Columbia
(604) 822-4906

MARGULIS, Lynn -

SCHOPF, William - UCLA Paleobiologist


Intelligent Design

xxx

3 Comments:

Blogger Jeremy said...

Your selective quotation from my essay on endosymbiosis gives the impression that science does not have an answer to the intriguing question of the origin of eukaryotes. However, as you hopefully know, the rest of my essay went on to describe the significant body of evidence supporting the endosymbiotic theory.

Unfortunately, the introductory sentence of my essay originally included the phrase "missing link." I consider this unfortunate because the phrase is a misleading description of transitional forms--it suggests a simple chain rather than the more complex branching pattern of evolutionary history.

I have since revised the introductory sentence so that it reads as follows:

"The transition between eukaryotes, cells with nuclei, and prokaryotes, cells which lack nuclei, is considered by many biologists to be the most profound change in evolutionary history."

While I do not expect you to officially acknowledge this change in your post, I do think it is important to point out that what the original sentence implied is not accurate.

12:51 PM  
Blogger Kevin Wirth said...

Jeremy,

Thanks for the comments you have offered regarding the context of your quote - such clarification is always welcome here. I am more than comfortable with receiving this note from you, as I do value accuracy.

As far as whether 'science' has an answer or not regarding the origin of eukaryotes, I would suggest that, as with any issue in science, the matter is far from settled. Those who claim that this matter has been put to rest clearly have not read many of the comments from credible sources I have seen which clearly indicate otherwise.

If you would care to provide me with a link to your corrected text, I would be happy to review it, and conside withdrawing my use of your quote or reposting your correction appropriately in this blog.

Thanks again,

Kevin

5:30 PM  
Blogger Jeremy said...

Kevin-

The link to the corrected text is the same as the original link.

Thanks for you attention to this matter.

Jeremy Mohn

9:54 AM  

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