Actually, different body plans are represented by the phyla. There are, approximately, 37 phyla, therefore, there are 37 different body plans. This is the definition of phyla. I don't know where you got your information about 5 different body plans. Again, read James W. Valentine's "On the Origin of Phyla". His material will really get you thinking. Oh, by the way, Chris Buttars is a certifiable moron. He is one of those people who is so stupid, they don't even know they're stupid. His threat of taking his fight to the public for a vote is absurd. Science is not subject to majority rule. If it was, we would never have come out of the Dark Ages. Dave Gary On Aug 28, 2005, at 7:33 PM, Canopus56 wrote:
Way back on August 23, Don Colton wrote:
I should next point out that I believe the earth is probably a few billions years old and that some form of life has been on the earth for over a billion years. There is also clear evidence of increasing complexity of life over that period of time. The question is what is the mechanism for the development of life on earth. It is interesting that 600 million years ago numerous complex life forms covering at least eight major phyla appeared suddenly without any significant intermediate predecessors. These life forms appeared in a very brief period of time (geologically speaking) and this fact was part of the evidence for Stephen J. Gould's theory of punctuated evolution. The Cambrian explosion is certainly contrary to Darwin's idea of slow progressive changes and I do not believe in can be explained by natural selection.
This enters the area of the distant geologic past during the pre-Cambrian explosion, where less is known with certainty about the geochemistry and ecological distribution of species. Fossils of the soft-body predecessors of hard-body pre-Cambrian organisms makes proving causal connections, whether by natural selection or intelligent design even more uncertain.
Don, I took some time to read a ID theorist Stephen Meyer's chapter in _Debating Design_. Meyer's overviews his theory that information theory invalidates the Darwinian explanation of the pre-Cambrian explosion. Meyer's case seems very weak and does not adequately prove that ID's core conclusion of causation by intelligent design could properly reached when applied to the pre-Cambrian explosion using ID theory’s own definitional criteria.
The pre-Cambrian era is unique in evolutionary history in that nine or so novel new body plans evolved in mutli-celluar organisms in a relatively short period of geologic time. Of the nine original body plans, only five survive today. No new novel body plans have evolved in the subsequent 560 million years.
ID theorist-founder Dembski established the following definitional requirements to the application of ID theory using the "scientific" form of argument from ignorance - eliminative induction:
1) The list of possible causes must be "exhaustive" so it includes the true cause. (If the list of causes only contains false causes, a false positive will be selected as the true cause.)
2) The list of possible causes must be "exclusive," meaning that there must be some means of distinguishing improbable false causes from the probable true cause.
3) The complexity of the effect (an object or process) must be "irreducibly complex," meaning the object or process cannot be broken down in smaller, less complex functional parts.
4) The likelihood of the spontaneous self-assembly of the irreducibly complex object or process must be so low, that it exceeds the "universal probability boundary" of 10^-150
When measured against these preconditions to ID's appropriate use, Meyer's reasoning and conclusion, that natural selection should be ruled out and that ID theory is the best explanation for the pre-Cambrian explosion, is weak. Natural selection remains the best explanation - even though based on weak sign.
Meyers makes the biomolecular and paleo-biological argument that the pre-Cambrian explosion happened over 5 x 10^6 (5,000,000) years. If the baseline rate of cellular mutation seen in present-day single-celled organisms is only 1 per million (1x10^6) mutations per generation, generational times are simply too high to permit the requisite number of generations to mutate a single-celled soft-bodied organism into a multi-celled hard-bodied organism. _Debating Design_ at 377.
Meyers goes on to argue that probability of favorable biomolecular mutations occurring is much lower. In the phase space of possible beneficial biochemical molecules and harmful biochemical molecules, there are only a few molecules that are beneficial that could be created out of the population of harmful and beneficial molecules. Even if random mutation could generate bio-chemically active molecules in the requisite period of time, the odds of generating a beneficial biologically active molecule within the required time period are just too small. See Figure 20.1 in _Debating Design_ at 380.
Meyers reasoning that ID theory can be properly applied to conclude that an intelligent designer is the cause of the pre-Cambrian explosion fails on a number of points:
First, the pre-Cambrian explosion occurred over a time frame of 100 million years - not 5 million years as Meyers supposes. One only has to look at how natural selection has evolved tundra wolves into ocean-going ocra whale over the last 60 million years to see just how radical a change that natural selection can induce in the exterior appearance of organisms over 60 million years.
Second, Meyers improperly assumes that his list of possible causes is exhaustive - based on his assumed mutation rate of 1 per million _for one organism_.
Meyers's reasoning about current known average mutation rate of 1 per million per generation in modern single-celled organisms is correct - but his reasoning is improperly based on applying that rate to one organism.
Let's take a modern bacteria like E coli. A single-cell of E. coli self-replicates under ideal conditions about once every 20 minutes or 1.2*10^3 seconds. After a 30 day month, the one E. coli cell has undergone 72 generations and created about 1.6*10^650 “daughter” organisms. Under Meyers's reasoning, the favorable mutation would have only occurred about 220 times (650/3). (Michael Crichton's 1969 sci-fi classic, The Andromeda Strain, was built-in around this hard-science.)
But the mutation rate for a single organism does not properly state the probability that a single mutation will be expressed in the environment. Rather, one has to take the total number of organisms in the environment and multiple that times the number of mutations expected to have occurred during a given time period. Take hospital-induced penicillin resistant bacteria. The odds of a single cell of bacteria randomly mutating the correct gene sequence to become resistant to penicillin within one person's lifetime infinitesimally small. However, penicillin resistant bacteria evolved in less than 30 years. Why? Because there are googles of individual bacteria undergoing gene mutation in a single hospital and each of those bacteria are having 1.6*10^650 "daughters" a month. Consequentially, the odds of penicillin resistant bacteria evolving in a hospital within your lifetime is near 100%.
The same analogy applies to the unknown state of affairs of Archean ocean's mix of single celled organisms and primitive mutli-celled organisms. For example, in a recent Utah astro-e-newsletter, the editor pointed out an August 18, 2005 study of the prevalence of the SAR11 single-celled organism in the modern world oceans. In that study, SAR11-type single-celled organisms were found to comprise more than 25% of the prokaryotes in a millimeter of Pacific Northwest near surface ocean water. It was estimated that there are 500,000 SAR11 cells in a single milliliter of ocean water. << http://aem.asm.org/cgi/content/abstract/71/6/2979
">25% of total prokaryotes " in seawater"
<< http://earthobservatory.nasa.gov/Newsroom/MediaAlerts/ 2005/2005081820000.html
"a milliliter of sea water off the Oregon coast
might contain 500,000 of these cells."
Now take the top 1 meter of the world's oceans. The world's oceans have a surface area of about 361 million km^2 << http://en.wikipedia.org/wiki/Ocean >>. One liter is 0.001 cubic meters. That works out to 3.61*10^14 cubic milliliters in the top meter of the world's oceans that might contain 1.8*10^20 SAR11 single-celled organisms. With that size of a population, the odds of a SAR11 cell expressing a randomly mutated gene in anyone month, somewhere in the world’s oceans, is 100%.
A more correct view of the Earth's ecology of single-celled organisms is an immense organic Babbage computer - and not Meyers’s overly reductionist view of the characteristics of a single cell.
The controlling question isn't Meyers's "Is the mutation rate too low in a single cell," but rather "Does the near certain expression of the mutation in a large population likely to occur in a favorable environment such that it will transmitted to following generations?" Once the gene conferring survival advantage is expressed - let's say in E. coli - it doesn't take a single-celled organism long to make 1.6*10^650 "daughters" expressing that gene.
In conclusion, Meyers improperly assumes that his list of possible causes is exhaustive - based on his assumed mutation rate of 1 per million _for one organism_.
Third, Meyers assumes that the current historical mutation rate of organisms of 1 per million per replication was true during the pre-Cambrian explosion 560,000,000 million years ago. This is a flawed assumption.
Intermediate amateur astronomers on this listserv are more aware than the generic public of just how variable the background radiation has been on the Earth's surface's during its 19 or 20 trips around the galactic core. Sol's orbit of the galactic core probably has taken it past and through many massive dark nebula that disturbed the Ort cloud, sending cascades of Earth bombarding comets into the inner solar system, and that collapsed the solar and geomagnetic fields. Sol has probably transited any number of nearby nova. Alpha Orion is a present-day nearby nova candidate that one day may triple the background radiation on the surface of the Earth for 10,000 years. The Sun itself was "bluer" and it's Achaean light had more uv, although its total luminosity was lower. The state of the Archean and pre-Cambrian ozone layer that blocks uv is not known with any certainty.
Taken together, these likely past events probably caused periods of higher levels of surface radiation on Earth. The higher the background radiation; the higher rate of cellular mutation.
Fourth, in his _Debating Design_ chapter, Meyers incorrectly reasons that natural selection occurs on the biomolecular level of the gene and not on the level of the organism. Meyers's reasoning assumes that natural selection only requires cells to accumulate beneficial mutations to genes. This is not the case because natural selection occurs on the level of the organism. It is possible for a genome to accumulate two harmful genes - that do not kill the organism off - and at a later time for natural selection to mutate a single gene into a positive survival enhancing gene. Another scenarios is the accumulation of two complex harmful genes that do not kill the organism - that are combined into a more complex positive gene at a later time. Again, this can occur because natural selection occurs at level of the organism and not at the level of the gene.
As an illustration of non-functioning genes hitching a ride, take SAR11, discussed above. SAR11 has one of the most efficient, compact genomes. Virtually every gene is biochemically active. In contrast, less-than 1/3 of the human genome is biochemically active. That's alot of organic "disk space" to hold information in structurally complex but non-functioning genes or in deactivated harmful genes. See - << http://earthobservatory.nasa.gov/Newsroom/MediaAlerts/ 2005/2005081820000.html
Looking at Meyers's first, second and third errors (described above), preconditions to applying ID theory (that "the list of possible causes must be ‘exhaustive’ so it includes the true cause" and that "The list of possible causes must be ‘exclusive,’ meaning that there must be some means of distinguishing improbable false causes from the probable true cause") have not been met because we know too little about pre-Cambrian organisms, ecology and geochemistry.
Meyers's implicitly acknowledges this uncertain level of knowledge regarding the pre-Cambrian fossil record and geochemistry in his chapter in _Debating Design_. And Meyers correctly points out that we also know too little with certainty about pre-Cambrian soft-bodied single-celled organisms that inductive proof of Darwinian natural selection will never occur with absolute certainty.
Here, Meyers argues that even if ID theory is possibly wrong because we have little certain knowledge about events occuring 560,000,000 years ago, ID theory is still the best uncertain theory among available competing uncertain theories. Therefore, ID theory's conclusion of intelligent design causation of the pre-Cambrian explosion should be accepted by the scientific community as the best scientific explanation:
"Studies in the history and philosophy of science have shown that many scientific theories, . . . are formulated and justified as inferences to the best explanation. . . .Those with greater explanatory power are typically judged to better - more probably true - theories. . . . . Clearly, we have good reason to doubt that either mutation and selection of self-organizational processes can produce the information-rich components, systems, and body plans that arose in the Cambrian. Instead, explaining the origin of such information requires causal powers that we uniquely associate with conscious and rational activity - with intelligent causes, not purely natural processes . . . Thus, based on our experience and analysis of the causal powers of various explanatory entities, we can infer Intelligent Design as the best - most causally adequate - explanation for the origin of the complex specified information required to build the Cambrian animals." Meyers, Debating Design at 387-389.
The problem with Meyers's conclusion is that this is not how science is done. He inverts the usual process applied to uncertain events in the natural world - inference based on inductive examples - with violations of basic tenets of ID's argument to ignorance or "eliminative induction." The way scientists reason based on induction from sign is one assembles numerous examples, albeit weak examples - the "signs", supporting a working hypothesis. If enough weak inductive samples are found, then the theory is assumed to be the "best explanation." This is the process that natural selection paleo-biologists use. One should reason from what affirmative weak signs that can be found in the fossil and geochemical record of the pre-Cambrian.
Meyers's ID "eliminative induction" based-reasoning turns this process upside down. He admits that he does not have enough affirmative inductive examples of intelligent design in pre-Cambrian fossil and/or geochemical record. Nonetheless, he "inductively eliminates" natural selection based on uncertain, hypothetical characteristics of organisms in the pre-Cambrian and then concludes ID theory is the "best explanation." This reasoning violates the basic tenet’s of ID "eliminative induction" reasoning - "eliminative induction" can only be used where the evidence of processes in the natural world can be known with some certainty. That constraint on reasoning to a true cause applies uniquely to "eliminative induction". Scientific reasoning by induction from sign (induction from weak affirmative evidence) does not suffer from the constraint of certainty as to all possible causes of an observed effect. Inductive reasoning from affirmative weak signs is proper scientific reasoning.
The same criticisms equally apply to ID theorist Walter Bradley's conclusion in _Debating Design_ that the origin of life - 3.8 billion years ago in the Achaean - occured by the action of an intelligent designer. We really don't know what was in the bio-molecular soup of the Achaean ocean. But that lack of knowledge does not, ipso facto, imply intelligent design. Conversely, weak knowledge of what was in the Achaean bio-molecular soup is proper fodder for inductive reasoning from sign.
Because ID practitioners apply bad scientific reasoning, ID theory should not be taught in the life science curriculum of Utah secondary schools. The purpose of a life-science secondary school science curriculum - like the physics and geo-science curriculum - is as an aid to teach teenagers how to reason - specifically how to apply the scientific method. Because ID theory does not rely on the mainstream scientific reasoning methods of proving a scientific hypothesis based on affirmative induction from sign or cause, ID theory is not ready for introduction in the curriculum of secondary schools.
Dark-skies are a-calling tonight. See ya!
- Canopus56(Kurt)
References:
Dembski, William A. (ed), Ruse, M. (ed.) 2004. Debating Design : From Darwin to DNA. Cambridge Univ. Press.
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