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Topic: Common descent

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 Common descent - CreationWiki   (Site not responding. Last check: 2007-10-21)
Common descent is the belief that all life evolved from a single, common ancestor or ancestor pool.
Belief in common descent is largely derived from the similarity among forms of life, particularly the common form and function of many forms of life.
Given a purported absence of hard evidence to support belief in common ancestry, creationists typically argue that common descent is a philosophical belief, not scientific, since the assertion is not falsifiable, and cannot be observed or tested by experiment.
www.nwcreation.net /wiki/index.php?title=Common_ancestry   (590 words)

 29+ Evidences for Macroevolution: the Scientific Case for Common Descent
In evolutionary theory it thus entails common ancestry, descent with modification, speciation, the genealogical relatedness of all life, transformation of species, and large scale functional and structural changes of populations through time, all at or above the species level (Freeman and Herron 2004; Futuyma 1998; Ridley 1993).
Common descent is a general descriptive theory that concerns the genetic origins of living organisms (though not the ultimate origin of life).
Similarly, universal common descent is restricted to the biological patterns found in the Earth's biota; it does not attempt to explain the ultimate origin of life.
www.talkorigins.org /faqs/comdesc   (2151 words)

 Teaching Evolution, Activity 4
One of the most common misconceptions about evolution is seen in the statement that "humans came from apes." This statement assumes that organisms evolve through a step-by-step progression from "lower" forms to "higher" forms of life and the direct transformation of one living species into another.
The theory of common descent also replaced a model of straight-line evolution with that of a branching model based on a single origin of life and subsequent series of changes—branching—into different species.
Label this strand "common ancestor DNA." This DNA strand represents a small section of the gene that codes for the hemoglobin protein of a common ancestor of the gorilla, chimpanzee, and human.
www.nap.edu /readingroom/books/evolution98/evol6-d.html   (2311 words)

 Common descent Info - Encyclopedia WikiWhat.com
In biology, the theory of universal common descent proposes that all organisms on Earth are descended from a common ancestor or ancestral gene pool.¹
This theory is now generally accepted by biologists, and the last universal common ancestor (LUCA), that is, the most recent common ancestor of all organisms, is believed to have appeared about 3.5 billion years ago.
The universality of the genetic code is generally regarded by biologists as definitive evidence in favor of the theory of universal common descent (UCD) for all bacteria, archaea, and prokaryotes (see Three domain system).
www.wikiwhat.com /encyclopedia/c/co/common_descent.html   (821 words)

 - Camp answers Theobald -
Common descent does predict specific biological universals, since any significant change (any “loss and replacement processes”) in the structures that perform the four basic life functions would result in nonviable organisms; these structures cannot be lost nor can they be replaced (although they can be expounded upon).
Common descent is not essential for nested hierarchy and therefore is not a necessary inference from the congruence of phylogenies based on different traits.
Third, common descent being false is not the same as there being no true phylogeny, so it is incorrect to identify the falsity of common descent with the absence of a true phylogeny.
www.trueorigin.org /ca_ac_01.asp   (12330 words)

 A response to Ashby Camp's "Critique"   (Site not responding. Last check: 2007-10-21)
Common descent does not predict that these structures must be identical, just that the similarity must be statistically significant, and that there must be viable intermediates between the variations.
Because of common descent, we know that certain types of organisms will be extremely similar in the biological universals before we actually go and check the organisms to see what their structures really look like.
And, as a deduction of common descent, the prediction of biological universals is testable, confirmable, and falsifiable.
www.evcforum.net /RefLib/CritiqueResponse.html   (17734 words)

 September 8, 2003
One was descent, with modification, from common ancestors, or, for simplicity, the hypothesis of descent with modification.
This is equivalent to “descent from a common ancestor” or “descent with modification”.
Evolution as “Descent from a Common Ancestor”— macroevolution.
home.att.net /~dmcleroy/Textbooks/Historical_Reality.htm   (4373 words)

 William Dembski | Teaching Intelligent Design   (Site not responding. Last check: 2007-10-21)
Darwinism is not identical with evolution understood merely as common descent.
Darwinism comprises a historical claim (common descent) and a naturalistic mechanism (natural selection operating on random variations), with the latter being used to justify the former.
Intelligent design therefore throws common descent itself into question but at the same time leaves open as a very live possibility that common descent is the case, albeit for reasons other than the Darwinian mechanism.
www.theism.net /article/16   (2387 words)

 Common descent - EvoWiki
Common descent is the idea that two populations or species share a common ancestral species, and are both descended from that ancestor by normal processes of replication.
The theory of common descent states that all species (on Earth, at least) share common ancestors, back to a single common ancestor of all life.
The mechanisms that produce diversity from common ancestors are those of the Theory of Evolution.
wiki.cotch.net /wiki.phtml?title=Common_descent   (200 words)

 Read about Common descent at WorldVillage Encyclopedia. Research Common descent and learn about Common descent here!   (Site not responding. Last check: 2007-10-21)
Earth are descended from a common ancestor or ancestral gene pool.
The first suggestion that all organisms may have had a common ancestor and diverged through random variation and natural selection was made in 1745 by the French mathematician and scientist
creationists do not accept the theory of universal common descent, arguing that humanity was created by God in a distinct act of creation, whereas the rest of life evolved.
encyclopedia.worldvillage.com /s/b/Common_descent   (1016 words)

 Jonathan Wells on Open Minded Research   (Site not responding. Last check: 2007-10-21)
After looking at the evidence for the latter (with a clarity and objectivity that is encouraged in an ID framework but discouraged in a Darwinian one), I concluded (as Phil Johnson did in Darwin On Trial) that the claim of universal common descent is philosophy-driven rather than evidence-driven.
The problem with universal common descent is not that it conflicts with ID, but that it conflicts with the evidence.
Incidentally, the distinction between my long-standing criticism of Darwinian mechanisms and my relatively recent skepticism about universal common descent is summarized in my response to the first question in an interview posted in January at http://www.idurc.org/wellsinterview.html.
www.theism.net /article.asp?id=15   (368 words)

 Compelling Data for Common Descent from Matching Redundant DNA Sequences
Once they diverged from their common source, the letters at site 2 and 5 were changed somehow, but the changes that were passed down still had to perform the function of defining the phone number 594-772-4963.
Since the DNA sequences are consistent with the expectation for a common ancestor, the evolution theory should be considered as the one of the two possible basic hypothesis supported by the data.
The strong evidence for common ancestors indicates that at least the general evolution theory is correct; however, scientist have not yet determined if the fundamental theory of evolution is correct for reasons explained in Section 6.
members.aol.com /SHinrichs9/descent/descent.htm   (8246 words)

 Evolutionblog: Hunter in Wonderland, Part Two
As she noted, rather than falsifying Darwin's idea of descent from a common ancestor, these “subtle derivatives” of the “standard” code actually provide powerful evidence for the common descent of all organisms from a single ancestor.
Comparative anatomy reveals many patterns of similarities that strongly suggest common descent (the identical bone structure of the forelimb in humans, whales and cats is a famous example).
The universal common ancestor possessed a genetic code, and that is the point from which evolution is considered to begin.
evolutionblog.blogspot.com /2004/09/hunter-in-wonderland-part-two.html   (2569 words)

 Primer: Genetic Evidence in a Nutshell
The hypothesis that all life forms are related through “common ancestry” can be tested by constructing hypothetical "family trees" (called "phylogenetic trees").
If common descent is true, trees should show neat lines of ancestry and inheritance that are consistent with common descent.
Furthermore, such analyses assume similarities are the result of common descent rather than "common design" (compare the limbs at right as evidence for "common design").
www.ideacenter.org /contentmgr/showdetails.php/id/1140   (213 words)

 Darwin's precursors and influences: 2. Common descent
One surprising statement of limited common descent is found in Linnaeus, the great originator of modern taxonomy, who is popularly cited to have thought that species were immutable.
Darwin's own statement was made by analogous reasoning from the common descent of lineages he had established: "I believe that animals are descended from at most only four or five progenitors, and plants from an equal or lesser number."
I do not think the evidence shows that Darwin was influenced in his theory of common descent directly by any precursor, although he clearly was dealing with the same problems set out by Lamarck, Lyell, Grant and Owen that others were.
www.biologie.uni-hamburg.de /b-online/e36_talk/precursors/precurs5.html   (854 words)

 Isn't it time to junk common descent?
As stated previously, one has far less flexibility in rearrangement of organisms by biological characteristics, since even though it has a wide distribution of different types of organisms, attempting to rearrange it and reclassify by other means will result in a large number of empty categories.
Common descent is not indicated where there is no descent at all.
The problem I have is common descent makes absolutely no sense to me and I think it holds back scientific discovery and thus a better understanding of our Creator.
debatingchristianity.com /forum/viewtopic.php?t=909   (3719 words)

 Sequences and Common Descent - Page by Wesley R. Elsberry
That is, we want to analyze sequences of proteins or DNA that arose in the last common ancestor or earlier, not sequences of things that arose later than the last common ancestor.
Since the last common ancestor of modern bacteria and modern metazoans is putatively the same species, we should expect that the sequence differences between modern bacteria and any modern metazoan should be the same as the difference between modern bacteria and any other modern metazoan.
The two do produce one anomaly, which is that the comparison to humans suggests that humans shared a more recent common ancestor with mice than with the equids, while the comparison to mice suggests that the mice shared a more recent common ancestor with equids than with the primates.
www.antievolution.org /people/wre/evc/argresp/sequence.html   (2242 words)

 Darwin's Tree of Life
Regardless of the status of a UCA, which is at the base of the tree of life, the entire debate has nothing to do with the branches of the tree -- the shared descent of eukaryotes, of animals, or common descent among vertebrates, arthropods, or angiosperms (Figure 5).
The concept of common ancestry is at the core of evolution.
Textbooks treat the concept of common descent in basically the same way as do scientists; they accept common ancestry of living things as a starting point, and proceed from there.
www.ncseweb.org /icons/icon2tol.html   (3814 words)

 Descent - Wikipedia, the free encyclopedia
Descent (computer game), a computer game released by Parallax Software in the mid-1990s
Descent (aircraft), the decrease of an aircraft in altitude during flight
"Descent" (TNG episode), an episode of Star Trek: The Next Generation
en.wikipedia.org /wiki/Descent   (127 words)

 Is Common Descent an Axiom of Biology?: Nelson, Paul
In this schema, which reflects the practice of evolutionary theorists, it is generative entrenchment that is imperiled by the observations, not common descent.  The problem now however is that common descent's empirical content, vis-á-vis the phenomena of development, is indeterminate.  One really can't say what follows observationally from the theory.
Most of us are familiar with the universal genetic code argument for common descent.  The argument first appeared in the mid to late 1960s, after the structure of the code was elucidated.  It is now widespread.
The theory of common descent...is "evolutionary" only in the most general sense, for it does not even refer to change.  It certainly is not tied to any particular model of the evolutionary process, nor is it at odds with the results of systematic analysis.
www.leaderu.com /orgs/arn/nelson/pn_darwinianparadigm061593.htm   (4513 words)

 Brainstorms: Common descent
I am taking Paul’s advice and starting a new thread focussed on common descent, although I think this topic will necessarily need to also include parts of the discussion of “miraculous” that was present in our previous discussion.
No break in the chain of common descent is necessary, so unless other arguments can be presented as to why common descent should be doubted, parsimony (among other things) leads me to accept common descent.
He is suggesting that multiple lineages of ancient fish, connected by common descent, converged on the terrestrial tetrapod lifestyle.
www.iscid.org /boards/ubb-get_topic-f-6-t-000056.html   (4914 words)

 Common descent   (Site not responding. Last check: 2007-10-21)
This theory is now generally accepted biologists and the last universal common ancestor (LUCA) that is the most recent common of all organisms is believed to have about 3.5 billion years ago (see: origin of life).
The universality of the genetic code is generally regarded by biologists as evidence in favor of the theory of common descent (UCD) for all bacteria archaea and eukaryotes (see Three domain system).
Some creationists do not accept the theory of common descent arguing that humanity was created God in a distinct act of creation the rest of life evolved.
www.freeglossary.com /LUCA   (1162 words)

 Stephen E. Jones: Creation/Evolution quotes: Evolution #3: Common ancestry (common descent)
But neither tell us anything about how the descent or evolution might have occurred, as to whether the process was gradual or sudden, or as to whether the causal mechanism was Darwinian, Lamarckian, vitalistic or even creationist.
Such a theory of descent is therefore devoid of any significant meaning and equally compatible with almost any philosophy of nature." (Denton M.J., "Evolution: A Theory in Crisis," Burnett Books: London, 1985, pp154-155).
All the humerus bones of the terrestrial vertebrates) for instances are thought to be derived by modification over millions and millions of years from the bones of the primitive limb-like fins of the first fish-like amphibia that pioneered the conquest of the land from the water.
members.iinet.net.au /~sejones/evolut03.html   (1408 words)

 Creation Essay 11
One problem with homology is the fact that numerous similarities among species cannot possibly be interpreted to mean descent from a common ancestor.
It is obvious that this distribution of hemoglobin does not fit with the idea that similarities indicate common descent, for nobody could believe that humans inherited their hemoglobin molecules from yeast.
Yet we see in the diagram that in six different vertebrates which allegedly inherited their front legs from a common ancestor, the front legs as well as the rear legs develop from entirely different groups of segments from species to species.
www.parentcompany.com /creation_essays/essay11.htm   (1395 words)

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