RNCSE 20 (3)

Reports of the National Center for Science Education
Volume: 
20
Issue: 
3
Year: 
2000
Date: 
May–June
Articles available online are listed below.

Dissecting the Disclaimer

Reports of the National Center for Science Education
Title: 
Dissecting the Disclaimer
Author(s): 
Kenneth Miller
Volume: 
20
Issue: 
3
Year: 
2000
Date: 
May–June
Page(s): 
30–33
This version might differ slightly from the print publication.
Recently the state of Oklahoma almost adopted a disclaimer to be placed in science textbooks that mention evolution and are used by public schools in the state. (See RNCSE 1999; 19 [5]: 7-8, 1999; 19 [6]: 11-2, and 2000; 20 [1-2]: 21). RNCSE readers will recognize that the wording of the Oklahoma disclaimer is taken directly from the infamous original textbook disclaimer proposed for textbooks in Alabama (see NCSE Reports 1995; 15 [4]:10-1). Unfortunately, the disclaimer is laden with scientific inaccuracies and distortions that will confuse students about the nature of science and the science of evolution. Such statements place an unwelcome burden on teachers, who must correct this misinformation for their students. They also introduce the dangerous precedent of setting official statements by public officials at odds with scientific accuracy and good educational practice.

What follows is a line-by-line analysis of the scientific accuracy of the disclaimer. The text of the disclaimer is set in boldface type, and my commentary is in plain type.

Message from the Oklahoma State Textbook Committee:

This textbook discusses evolution, a controversial theory, which some scientists present as scientific explanation for the origin of living things, such as plants and humans.

This statement is a deliberate attempt to mislead young readers about the scientific standing of evolutionary biology. Within the scientific community, evolution is anything but controversial. Rather, as the National Academy of Sciences states, evolution is "the most important concept in modern biology" (NAS 1998, viii). Saying that "some" scientists present evolution as the explanation for the origin of species is equally misleading. It is like saying that "some" scientists believe that matter is composed of small units they call atoms. That statement would also be true, but would convey a false sense of uncertainty regarding atomic theory. A more accurate statement would tell students that evolution is accepted by the vast majority of life scientists around the world, and by every leading scientific organization in the United States including the National Academy of Sciences, as the best available explanation for the origin of species.

No one was present when life first appeared on earth.

Absolutely correct.

Therefore, any statement about life's origins should be considered as theory, not fact.

This statement manifests a serious misunderstanding of the scientific usage of the terms "theory" and "fact". A theory in science is an explanation of a natural phenomenon, and a fact is a confirmed observation. An example of a fact would be that there is great consistency in the sequence of fossils in the fossil record, with no major branch of the tree of life being out of order (for example, fossils of mammals are never found in the Devonian Period - a time marked by the diversification of bony fishes and the appearance of the first amphibians and insects). Another fact is that living species tend to be found where their fossil ancestors are also found. We make sense of these and many other confirmed observations, or facts, with the explanation that living things share common ancestors, from which they have diverged. This explanation is the theory of evolution, an extremely strong and well-supported theory. The disclaimer will confuse students about these important elements of science. Theories explain facts, and contrary to the impression given by the disclaimer, this means that theories are more important than facts.

The disclaimer also will confuse students about the nature of science by implying that science concerns only directly observable phenomena. Actually, many scientific discoveries are made about phenomena that are not directly observable, such as those that are too far away (astronomy) or too small (particle physics) as well as those that occurred in the past (geology and evolutionary biology). That "no one was there to see it" does not mean that it cannot be studied scientifically or that we cannot have confidence in our explanations.

Ironically, well-written science textbooks place even less confidence in current ideas about how life may have originated than the disclaimer does. Typically, ideas about the origin of life are regarded as hypotheses, placing them a rung lower on the scientific hierarchy of ideas than the textbook committee was willing to do. (A typical example is this: "How then did life begin? ... Although several hypotheses have tried to explain how life may have arisen, we may never know the answers" [Miller and Levine 1998, 398].) The disclaimer makes a serious error by elevating current hypotheses about the origin of life to the status of theories (which would mean that they are generally accepted by the scientific community).

The word evolution may refer to many types of change. Evolution describes changes that occur within a species. (White moths, for example, may evolve into gray moths). This process is micro evolution, which can be observed and described as fact.

Evolutionary biologists use "microevolution" to refer to the processes (most of them having to do with genetics) that produce evolutionary changes in populations of species: natural selection, mutation, migration, genetic drift, and other mechanisms. The writers of the disclaimer apparently share this definition, and are correct in noting that we can observe these processes at work.

Evolution may also refer to the change of one living thing into another, such as reptiles into birds. This process, called macro evolution, has never been observed and should be considered a theory. Here the writers of the disclaimer do not use the scientific meaning of the crucial term. "Macroevolution", for evolutionary biologists, refers to a range of processes having to do with the pattern of evolutionary change: how groups are related to one another above the level of the species, rates of evolutionary change, the behavior of lineages over time, and so forth. But in the disclaimer, the term "macroevolution" means merely the general principle of evolution: that living things have descended with modification from common ancestors. This is not what macroevolution means in science, and to use the term as a synonym for evolution misleads and confuses students.

Clearly, the writers of the disclaimer want students to reject the idea that living things have a common ancestry, and they are in the bind of having to accept well-understood and widely-demonstrated processes of evolutionary change, which, over time, would result in evolution. The reason for this is at bottom a sectarian religious belief known as "special creation": that all living things were created in their present form and did not descend with modification from common ancestors. Special creation is not supported by science - regardless of how the authors of the disclaimer attempt to redefine scientific terms.

Evolution is not rigidly divided into two types of change -microevolution and macroevolution - as the disclaimer implies. Macroevolution, for example, may be used to refer to the process of speciation, to major evolutionary transformations, or both. Most importantly, it is commonly accepted among evolutionary biologists that microevolutionary changes (whether caused by natural selection or by genetic drift) can accumulate so as to cause reproductive isolation, hence leading to speciation or macroevolution. Has macroevolution "never been observed"? A recent study (Reznick and others 1997) evaluated the observed rates of evolutionary change in populations of guppies (Poecilia reticulata) in the wild. The rates of evolutionary change observed were "up to 7 orders of magnitude greater than rates inferred from the paleontological record." In other words, field studies of natural selection show rates of change easily more than large enough to account for the macroevolutionary changes documented in the fossil record. This is just one of many studies that cast serious doubt on the assertion that macroevolution has "never been observed." (The researchers also note: "Our work cannot address the efficacy of mechanisms other than natural selection, but it extends our understanding of what is attainable through this process. It is part of a growing body of evidence that the rate and patterns of change attainable through natural selection are sufficient to account for the patterns observed in the fossil record" (Reznick and others 1997: 1936).

Evolution also refers to the unproven belief that random, undirected forces produced a world of living things.

This statement is false on 2 counts. Evolution is not a "random" process, and to characterize it so seriously misleads students. Natural selection, the most important force driving evolutionary change, is not random at all, but an observable, verifiable process that fine-tunes variation in populations of a species to the demands of the environment in which they live. It is true, of course, that variation in a species arises from sources such as mutation and sexual recombination, which are inherently unpredictable. Therefore evolution, like any historical process, can be influenced by random forces.

But a larger problem with this statement is the attribution to evolution of an idea outside of science. Whether evolution is "undirected" or "directed" is a matter for theology or philosophy, not of science. Writers of the disclaimer wish for students, most of whom are religious, to believe that acceptance of evolution is incompatible with faith. This is demonstrably false: far too many scientists (and clergy) accept both evolution and a God who creates through evolution. Students should not be taught that evolution equates with atheism, yet, incredibly, that is exactly what this portion of the disclaimer says.

There are many unanswered questions about the origin of life, which are not mentioned in your textbook, ...

It is absolutely true that there are "many unanswered questions about the origin of life", and most biology textbooks point this out in far greater (and more accurate) detail than does the disclaimer. Indeed, there are unanswered questions in each and every area of biology, making biology an exciting and vigorous discipline. The disclaimer, however, does not seek to draw student attention to unanswered questions in biochemistry, ecology, or physiology; it singles out evolution for special attention, as if it had special difficulties that other fields do not.

Scientifically, this is not correct, and the next few sentences of the disclaimer show just how badly informed its authors were:

... including: Why did the major groups of animals suddenly appear in the fossil record, known as the Cambrian Explosion?

This question seriously misleads students about the actual natural history of this planet. The term "major group" lacks scientific meaning. Many students, for example, might regard the mammals as a major group. Mammals, however, did not appear during the Cambrian explosion, but rather in the Triassic, nearly 300 million years later. The same can be said of birds, insects, reptiles, and amphibians, each of which are major groups in the ordinary meaning of the term, and none of which appeared in the Cambrian period. Clearly, the authors of the statement could have prevented such confusion by referring only to the animal phyla instead of "major groups".

Unfortunately, even if they had done so, the question would still be misleading. Not all animal phyla originated during the Cambrian. Compounding this serious mistake, the authors of the disclaimer seem to be unaware that the first multicellular animals appeared on earth during the Ediacaran Period, and many predate the Cambrian by more than 100 million years.

Why have no new major groups of living things appeared in the fossil record in a long time?

This peculiar question requires students to determine what is meant by a "major group" and also what is meant by "a long time". Neither term, of course, has any scientific meaning. One might regard 100 years as a long time, and it is indeed true that no new phyla have originated in the last 100 years. However, by standards of geologic time, one of the most important "major groups of living things" did indeed originate recently. Flowering plants (the Anthophyta) appeared for the first time in the Cretaceous, roughly 125 million years ago. Flowering plants appeared only in the last 3% of the 4.5 billion years of the planet's geologic history, which certainly qualifies as recent. Therefore, this question, which overlooks the recent evolutionary appearance of flowering plants, makes blatantly wrong presuppositions.

Why do major groups of plants and animals have no transitional forms in the fossil record?

This question also makes blatantly wrong presuppositions. The fossil record is, in fact, replete with splendid examples of transitional forms, as the National Academy of Sciences has taken pains to point out:

So many intermediate forms have been discovered between fish and amphibians, between amphibians and reptiles, between reptiles and mammals, and along the primate lines of descent that it often is difficult to identify categorically when the transition occurs from one to another particular species. Actually, nearly all fossils can be regarded as intermediates in some sense; they are life forms that come between the forms that preceded them and those that followed (NAS 1999: 21).

How did you and all living things come to possess such a complete and complex set of instructions for building a living body?

This is an excellent question, and students would be well-advised to keep it in mind as they study biology. They may wonder why, for example, the "complex set of instructions" referred to by this sentence includes the genetic remnants of an ancient infection by an HIV-like virus. The interesting fact about these genetic remnants is that they are found not only in humans, but in our closest primate relatives, indicating that these viral DNA sequences entered the genome roughly 30 million years ago. As the investigators who made this discovery pointed out, the existence of identical sequences in closely related species is "very good evidence" that we share a common ancestry with these other primates (Yang and others 1999). As the National Academy of Sciences has written, "compelling lines of evidence demonstrate beyond any reasonable doubt that evolution occurred as a historical process and continues today" (NAS 1998, 16).

Study hard and keep an open mind. Someday you may contribute to the theories of how living things appeared on earth.

At last, some excellent advice!

By any standard, this disclaimer fails even an undemanding test of scientific literacy. Twelve statements are included in the disclaimer. Of these, only 5 are free of major errors. Three are seriously misleading, and 4 are downright false. A biology teacher grading this disclaimer based on the proportion of correct answers would calculate a score of no more than 42% - a failing grade.

Our students deserve better.

To be sure, the disclaimer's admonition that students study hard and keep an open mind fits the best traditions of scientific study. But keeping an open mind does not mean that students should intentionally be taught nonsense, nor does it mean that we should pretend to know less than we do about the natural history of this planet and the origins of species, including our own. Healthy skepticism is at the core of a scientific education, but elevating falsehoods and half-truths to the status of scientific theory most definitely is not.

I would argue that any textbook, indeed, any course in the biological sciences should tell students the plain and simple truth, as described in a single sentence by the National Academy of Sciences: that "[b]iological evolution is the best scientific explanation we have for the enormous range of observations about the living world" (NAS 1999: 28).

References

Miller KR, Levine J. Biology: The Living Science. Upper Saddle River (NJ): Prentice-Hall 1998.

National Academy of Sciences (NAS). Teaching about Evolution and the Nature of Science. Washington DC: National Academy Press 1998.

National Academy of Sciences (NAS). Science and Creationism: A View from the National Academy, 2nd. ed. Washington DC: National Academy Press 1999.

Reznick DN, Shaw FH, Rodd FH, Shaw RG. Evaluation of the Rate of Evolution in Natural Populations of Guppies (Poecilia reticulata). Science 1997 Mar 28; 275: 1934-7.

Yang J, Bogerd HP, Peng S, Heather Wiegand H, Truant R, Cullen BR. An ancient family of human endogenous retroviruses encodes a functional homolog of the HIV-1 Rev protein. Proceedings of the National Academy of Sciences 1999 Nov 9; 96 [23]: 13404-8.

About the Author(s): 
Kenneth R Miller
Department of Biology
Brown University
Providence RI 02912

Nuclear Isochrons

Reports of the National Center for Science Education
Title: 
Nuclear Isochrons
Author(s): 
Dave Thomas
Volume: 
20
Issue: 
3
Year: 
2000
Date: 
May–June
Page(s): 
26–29
This version might differ slightly from the print publication.

Some chemical elements have isotopes that are inherently unstable and undergo radioactive decay. (Isotopes of the same element always have the same number of charged protons in each atomic nucleus, but have different numbers of noncharged neutrons. Isotopes of a single element act the same chemically, but often behave differently as regards radioactivity or other nuclear reactions.) Each radioactive isotope has a remarkably constant decay rate. These can be measured quite accurately, and most are constant under a huge range of conditions (temperature, pressure, and so on). The laws of physics do not tell us which atoms of a given isotope (say, uranium-238) will decay at any given time; but they do tell us how long it will take for, say, half of the atoms to decay — this duration is called the "half-life"; it is independent of the size of the sample. It is a lot like insurance mortality tables — for a given age group, actuaries cannot predict which individuals are good risks, but they can predict things such as the average life expectancy of members of the group and how long it will take for half of the group to succumb to accidents or natural causes.

"Simple" radioactive dating can be visualized as using a kind of atomic hourglass. The radioactive "parent" decays into a "daughter" isotope (often of a different element, since radioactive decays usually involve charged particles). So, if both parent and daughter elements are present, the ratio of parent isotope to daughter isotope can give a clue to the age of the sample. If there is more parent than daughter, the sample is still young (the top of the hourglass is still mostly full). If there is less parent than daughter, the sample is old (most of the sand is at the bottom of the hourglass).

But simple dating techniques can be distorted in several ways. What if there were some of the daughter isotope in the sample when it was formed? (Or, by analogy, what if the hourglass had some sand already in the bottom vessel when the hourglass was first placed upright?) What if the sample were not a "closed system", and isotopes (either parent or daughter) could enter or leave the system? (What if there were holes in either vessel of the hourglass that could let sand grains in or out?) Such contingencies clearly could affect estimates of how long the "clock" has been running.

To give a concrete example, suppose that we examine 3 different minerals from a rock, labeled A, B, and C, and that isotopic tests revealed the relative amounts of 3 chemical isotopes in these minerals. The parent isotope is rubidium-87 (87Rb for short). It is radioactive, has 37 protons and 50 neutrons (for a total of 87 nucleons), and beta-decays to strontium-87 with a half-life of 49 billion years. The daughter isotope, strontium-87 (87Sr), has 38 protons and 49 neutrons (for a total of 87 nucleons). 87Sr is formed when one neutron of a 87Rb atom decays to a proton, ejecting an electron (or "beta ray"). A third isotope required is strontium-86 (86Sr); this is not involved in any radioactive reactions (and thus is "non-radiogenic").

The present-day relative amounts of the isotopes in our fictitious example are:

Mineral 87Rb 87Sr 86Sr
A 60 80 40
B 30 60 60
C 10 60 100


These numbers are purely hypothetical — they were chosen so the explanation would be easy to understand. I decided to make the rock 49 billion years old, one half-life of rubidium. (Yes, that is much older than the universe, but this is merely an example.)

If we were to apply the "simple" dating method to A, B, and C, we would arrive at 3 different ages, assuming that there was no initial daughter isotope (87Sr) when the rock formed. For mineral A, all 80 units of 87Sr would be assumed to have once been 87Rb, so the initial amount of 87Rb would be 60 + 80 = 140. The corresponding age works out to be 1.222 half-lives, or about 60 billion years. [T = T1/2 log2((87Rb + 87Sr) / 87Rb) = 49 BY log2(140 / 60)]. Similarly, mineral B would appear to have an age of 78 BY, and mineral C would appear to have an age of 138 BY. Thus the presence of initial daughter atoms devastates the validity of "simple" dating methods.

There are 3 important questions to consider when choosing a mineral sample for radiometric dating: (1) Is the rock a good sample for radioactive dating? (2) What was the initial amount of daughter product (87Sr) in the rock at the time it formed out of a melt? (3) How old is the rock? The isochron technique provides a way to answer these questions.

Imagine going back in time 49 billion years to observe the rock as it is crystallizing from a melt. The rock has both isotopes of strontium: the daughter product 87Sr and non-radiogenic 86Sr. Because these all have nearly identical chemical characteristics, they are mixed in equal ratios throughout the melted rock, much as a drop of food coloring stirred into a glass of water quickly diffuses into a uniform hue. Ratios are the "secret" of the isochron method, and we need just 2 ratios: the ratio of the radioactive parent isotope (87Rb) to the non-radiogenic isotope (86Sr), and the ratio of the daughter isotope (87Rb) to the same non-radiogenic isotope (86Sr). These are given in the following table for the assumed time of crystallization (49 BY ago).



The rubidium-heavy mineral A has the highest ratio; A’s ratio of parent isotope to non-radiogenic isotope is 120 / 40 = 3.0. In contrast, the rubidium-poor mineral C has the lowest ratio; C’s ratio of parent isotope to non-radiogenic isotope is 20 / 100 = 0.2. Note that all of the minerals have the same ratio of daughter isotope to non-radiogenic isotope: 0.5, or 1/2. This is a direct result of the uniform mixing of the melted isotopes.

Now let us return to the present and see what has happened to our rock. The next table shows the present-day amounts and ratios of the isotopes.



Because the time elapsed since the rock solidified is one half-life of 87Rb, half of the ancient amount will have decayed by the present. So for mineral A, which started with 120 units of 87Rb, now 60 remain, with the other 60 converted to the daughter isotope (87Sr). Thus, as the 87Rb amount drops from 120 to 60, the 87Sr count goes from 20 (49 BYa) to 80 (now). The story is similar for mineral B, which has an 87Rb change of 60 down to 30, and a corresponding 87Sr increase of 30 up to 60. Try the rule out on mineral C to see for yourself how this works. The important thing is that the ratios have changed also — the 87Rb ratios all dropped, and the 87Sr ratios, which used to all be 1/2, are now quite different (ranging from 0.6 to 2.0).

So what is an isochron, anyway? If the results of the preceding tables are graphed with the parent isotope ratio as the horizontal axis, and the daughter isotope ratio as the vertical axis, then the slope of the isochron — the line connecting the points for the various minerals at the same time (as the etymology of the name "isochron" suggests) — is directly related to the age of the rock. Two such isochrons are shown below: the horizontal one labeled 49 BYa, and the slanted one (lower left to upper right) labeled NOW.

The lines with arrows represent the changes in those single minerals over time. For example, A’s 87Rb/86Sr ratio drops from 3.0 to 1.5, while its 87Sr/86Sr ratio rises from 0.5 to 2.0. Compare the plot to the ratios in the preceding tables to see where the isochrons come from.

How is the isochron’s slope related to the age of the rock? Let us consider one more example — that of the same rock, 49 BY in the future (long after our sun has turned into a smoldering dwarf star).



The slope of the far-future isochron is (2.75 - 0.65) / (0.75 - 0.05) = 2.1 / 0.7 = 3.0. The age is obtained by adding 1.0 to the slope, and then stating the sum as a power of two; that power is the age, in half-lives. For a slope of 3, 3 + 1 = 4 = 22, so the age is 2 half-lives. For a slope of 1 (present-day), 1 + 1 = 2 = 21, so the age is 1 half-life. And for a slope of 0.0 (49 BY ago), 0 + 1 = 1 = 20, so the age is zero. In general, the number of half-lives is the base 2 logarithm of (the isochron’s slope + 1). For a slope of 7, slope + 1 = 8 = 23, which means 3 half-lives.

When applied correctly, the isochron method provides a powerful way to tackle some of the problems encountered with "simple" dating techniques. For one thing, if the sample minerals did not solidify at the same time but were mashed together, the points will generally not lie on a straight line. And when this scattering is observed, the sample is recognized to be unusable for dating with the method. It is like a built-in quality check on the reliability of the result. For another thing, the possibility of having some of the daughter isotope already present in the rock when it formed can be handled . This initial amount is revealed by the isochron method — as the value on the 87Sr/86Sr axis where the isochron crosses (0.5 in all the examples). And since the age depends on the isochron slope, the initial amount does not affect the age determination (unlike "simple" dating).

But the method is not infallible. For example cases of non-uniform mixing, or conglomeration of certain types of rocks, can sometimes lead to "false" or "fictitious" isochrons — isochrons that do not represent the true age of the rock. These possible pitfalls are discussed in Bernard-Griffiths (1989) and Faure (1986). There are methods to counteract these problems, such as taking more mineral samples, performing mixture analyses on more than one element, and by checking dates by independent means (such as looking at different parent/daughter pairs). (For more details on this and other methods, see the chapter on dating techniques in Dalrymple [1991] and York and Dalrymple [2000].) When such checks are made, confidence in the results is greatly increased. For example, the St Severin meteorite was dated with three different methods (Rb-Sr, Sm-Nd, and Ar-Ar) as being between 4.4 and 4.6 billion years old (Dalrymple 1991, 288).

Creationists love to attack such methods by claiming that we do not really know if radioactive decay rates are constant over time. They point out no human was around back then, so who knows for sure? They also hypothesize that decay rates varied during supernatural events (the Creation, the Flood), but of course they do not test these hypotheses. One interesting point against the creationists is the fact that, if decay rates did change over time, the points on an isochron plot would be forced off the isochron line and would appear quite scattered. The very fact that isochrons do work in many cases is powerful evidence that decay rates have, in fact, remained constant for billions of years.

This article originally appeared in NMSR Reports 1997 May; 3 (5): 5–7. It is reprinted and abridged with permission.

References

Bernard-Griffiths J. In: Roth E, Doty B, editors. Nuclear Methods of Dating. Boston: Kluwer Academic Publishers, 1989. p 80–94.
Dalrymple GB. The Age of the Earth. Stanford (CA): Stanford University Press 1991.
Faure G. Principles of Isotope Geology>. 2nd ed. NY: John Wiley and Sons, 1989.
York D, Dalrymple GB. Comments on a creationist’s irrelevant discussion of isochrons. Reports of the National Center for Science Education> 2000 May/Jun; 20 [3]: xx–xx.

About the Author(s): 
Dave Thomas is the president of New Mexicans for Science and Reason and editor of NMSR Reports. He was a 1999 recipients of NCSE’s Friend of Darwin awards and the winner of NCSE's "Tangible Benefits of Evolution" contest.

Dave Thomas
PO Box 1017
Peralta NM 87042
E-mail: det@rt66.com

Radiometric Dating Does Work!

Reports of the National Center for Science Education
Title: 
Radiometric Dating Does Work!
Author(s): 
G. Brent Dalrymple
Volume: 
20
Issue: 
3
Year: 
2000
Date: 
May–June
Page(s): 
14–19
This version might differ slightly from the print publication.

Radiometric dating of rocks and minerals using naturally occurring, long-lived radioactive isotopes is troublesome for young-earth creationists because the techniques have provided overwhelming evidence of the antiquity of the earth and life. Some so-called creation scientists have attempted to show that radiometric dating does not work on theoretical grounds (for example, Arndts and Overn 1981; Gill 1996) but such attempts invariably have fatal flaws (see Dalrymple 1984; York and Dalrymple 2000). Other creationists have focused on instances in which radiometric dating seems to yield incorrect results. In most instances, these efforts are flawed because the authors have misunderstood or misrepresented the data they attempt to analyze (for example, Woodmorappe 1979; Morris HM 1985; Morris JD 1994). Only rarely does a creationist actually find an incorrect radiometric result (Austin 1996; Rugg and Austin 1998) that has not already been revealed and discussed in the scientific literature.

The creationist approach of focusing on examples where radiometric dating yields incorrect results is a curious one for two reasons. First, it provides no evidence whatsoever to support their claim that the earth is very young. If the earth were only 6000–10 000 years old, then surely there should be some scientific evidence to confirm that hypothesis; yet the creationists have produced not a shred of it so far. Where are the data and age calculations that result in a consistent set of ages for all rocks on earth, as well as those from the moon and the meteorites, no greater than 10 000 years? Glaringly absent, it seems.

Second, it is an approach doomed to failure at the outset. Creationists seem to think that a few examples of incorrect radiometric ages invalidate all of the results of radiometric dating, but such a conclusion is illogical. Even things that work well do not work well all of the time and under all circumstances. Try, for example, wearing a watch that is not waterproof while swimming. It will probably fail, but what would a reasonable person conclude from that? That watches do not work? Hardly.

A few verified examples of incorrect radiometric ages are simply insufficient to prove that radiometric dating is invalid. All they indicate is that the methods are not infallible. Those of us who have developed and used dating techniques to solve scientific problems are well aware that the systems are not perfect; we ourselves have provided numerous examples of instances in which the techniques fail. We often test them under controlled conditions to learn when and why they fail so we will not use them incorrectly. We have even discredited entire techniques. For example, after extensive testing over many years, it was concluded that uranium-helium dating is highly unreliable because the small helium atom diffuses easily out of minerals over geologic time. As a result, this method is not used except in rare and highly specialized applications. Other dating techniques, like K-Ar (potassium-argon and its more recent variant 40Ar/39Ar), Rb-Sr (rubidium-strontium), Sm-Nd (samarium-neodynium), Lu-Hf (lutetium-hafnium), and U-Pb (uranium-lead and its variant Pb-Pb), have all stood the test of time. These methods provide valuable and valid age data in most instances, although there is a small percentage of cases in which even these generally reliable methods yield incorrect results. Such failures may be due to laboratory errors (mistakes happen), unrecognized geologic factors (nature sometimes fools us), or misapplication of the techniques (no one is perfect). In order to accomplish their goal of discrediting radiometric dating, however, creationists are faced with the daunting task of showing that a preponderance of radiometric ages are wrong — that the methods are untrustworthy most of the time. Not only that, they have to show the flaws in those dating studies that provide independent corroborative evidence that radiometric methods work. This is a tall order and the creationists have made no progress so far.

It is rare for a study involving radiometric dating to contain a single determination of age. Usually determinations of age are repeated to avoid laboratory errors, are obtained on more than one rock unit or more than one mineral from a rock unit in order to provide a cross-check, or are evaluated using other geologic information that can be used to test and corroborate the radiometric ages. Scientists who use radiometric dating typically use every means at their disposal to check, recheck, and verify their results, and the more important the results the more they are apt to be checked and rechecked by others. As a result, it is nearly impossible to be completely fooled by a good set of radiometric age data collected as part of a well-designed experiment.

The purpose of this paper is to describe briefly a few typical radiometric dating studies, out of hundreds of possible examples documented in the scientific literature, in which the ages are validated by other available information. I have selected four examples from recent literature, mostly studies involving my work and that of a few close colleagues because it was easy to do so. I could have selected many more examples but then this would have turned into a book rather than the intended short paper.

The Manson Meteorite Impact and the Pierre Shale

In the Cretaceous Period, a large meteorite struck the earth at a location near the present town of Manson, Iowa. The heat of the impact melted some of the feldspar crystals in the granitic rocks of the impact zone, thereby resetting their internal radiometric clocks. These melted crystals, and therefore the impact, have been dated by the 40Ar/39Ar method at 74.1 Ma (million years; Izett and others 1998), but that is not the whole story by a long shot. The impact also created shocked quartz crystals that were blasted into the air and subsequently fell to the west into the inland sea that occupied much of central North America at that time. Today this shocked quartz is found in South Dakota, Colorado, and Nebraska in a thin layer (the Crow Creek Member) within a thick rock formation known as the Pierre Shale. The Pierre Shale, which is divided into identifiable sedimentary beds called members, also contains abundant fossils of numerous species of ammonites, ancestors of the chambered nautilus. The fossils, when combined with geologic mapping, allow the various exposed sections of the Pierre Shale to be pieced together in their proper relative positions to form a complete composite section (Figure 1). The Pierre Shale also contains volcanic ash that was erupted from volcanoes and then fell into the sea, where it was preserved as thin beds. These ash beds, called bentonites, contain sanidine feldspar and biotite that has been dated using the 40Ar/39Ar technique.Figure 1Figure 1

The results of the Manson Impact/Pierre Shale dating study (Izett and others 1998) are shown in Figure 1. There are three important things to note about these results. First, each age is based on numerous measurements; laboratory errors, had there been any, would be readily apparent. Second, ages were measured on two very different minerals, sanidine and biotite, from several of the ash beds. The largest difference between these mineral pairs, in the ash from the Gregory Member, is less than 1%. Third, the radiometric ages agree, within analytical error, with the relative positions of the dated ash beds as determined by the geologic mapping and the fossil assemblages; that is, the ages get older from top to bottom as they should. Finally, the inferred age of the shocked quartz, as determined from the age of the melted feldspar in the Manson impact structure (74.1 ± 0.1 Ma), is in very good agreement with the ages of the ash beds above and below it. How could all of this be so if the 40Ar/39Ar dating technique did not work?

The Ages of Meteorites

Meteorites, most of which are fragments of asteroids, are very interesting objects to study because they provide important evidence about the age, composition, and history of the early solar system. There are many types of meteorites. Some are from primitive asteroids whose material is little modified since they formed from the early solar nebula. Others are from larger asteroids that got hot enough to melt and send lava flows to the surface. A few are even from the Moon and Mars. The most primitive type of meteorites are called chondrites, because they contain little spheres of olivine crystals known as chondrules. Because of their importance, meteorites have been extensively dated radiometrically; the vast majority appear to be 4.4–4.6 Ga (billion years) old. Some meteorites, because of their mineralogy, can be dated by more than one radiometric dating technique, which provides scientists with a powerful check of the validity of the results. The results from three meteorites are shown in Table 1. Many more, plus a discussion of the different types of meteorites and their origins, can be found in Dalrymple (1991).

Table 1Table 1 There are 3 important things to know about the ages in Table 1. The first is that each meteorite was dated by more than one laboratory — Allende by 2 laboratories, Guarena by 2 laboratories, and St Severin by four laboratories. This pretty much eliminates any significant laboratory biases or any major analytical mistakes. The second thing is that some of the results have been repeated using the same technique, which is another check against analytical errors. The third is that all three meteorites were dated by more than one method — two methods each for Allende and Guarena, and four methods for St Severin. This is extremely powerful verification of the validity of both the theory and practice of radiometric dating. In the case of St Severin, for example, we have 4 different natural clocks (actually 5, for the Pb-Pb method involves 2 different radioactive uranium isotopes), each running at a different rate and each using elements that respond to chemical and physical conditions in much different ways. And yet, they all give the same result to within a few percent. Is this a remarkable coincidence? Scientists have concluded that it is not; it is instead a consequence of the fact that radiometric dating actually works and works quite well. Creationists who wants to dispute the conclusion that primitive meteorites, and therefore the solar system, are about 4.5 Ga old certainly have their work cut out for them!

The K-T Tektites

One of the most exciting and important scientific findings in decades was the 1980 discovery that a large asteroid, about 10 kilometers diameter, struck the earth at the end of the Cretaceous Period. The collision threw many tons of debris into the atmosphere and possibly led to the extinction of the dinosaurs and many other life forms. The fallout from this enormous impact, including shocked quartz and high concentrations of the element iridium, has been found in sedimentary rocks at more than 100 locations worldwide at the precise stratigraphic location of the Cretaceous-Tertiary (K-T) boundary (Alvarez and Asaro 1990; Alvarez 1998). We now know that the impact site is located on the Yucatan Peninsula. Measuring the age of this impact event independently of the stratigraphic evidence is an obvious test for radiometric methods, and a number of scientists in laboratories around the world set to work. Table 2Table 2 In addition to shocked quartz grains and high concentrations of iridium, the K-T impact produced tektites, which are small glass spherules that form from rock that is instantaneously melted by a large impact. The K-T tektites were ejected into the atmosphere and deposited some distance away. Tektites are easily recognizable and form in no other way, so the discovery of a sedimentary bed (the Beloc Formation) in Haiti that contained tektites and that, from fossil evidence, coincided with the K-T boundary provided an obvious candidate for dating. Scientists from the US Geological Survey were the first to obtain radiometric ages for the tektites and laboratories in Berkeley, Stanford, Canada, and France soon followed suit. The results from all of the laboratories were remarkably consistent with the measured ages ranging only from 64.4 to 65.1 Ma (Table 2). Similar tektites were also found in Mexico, and the Berkeley lab found that they were the same age as the Haiti tektites. But the story doesn’t end there.

The K-T boundary is recorded in numerous sedimentary beds around the world. The Z-coal, the Ferris coal, and the Nevis coal in Montana and Saskatchewan all occur immediately above the K-T boundary. Numerous thin beds of volcanic ash occur within these coals just centimeters above the K-T boundary, and some of these ash beds contain minerals that can be dated radiometrically. Ash beds from each of these coals have been dated by 40Ar/39Ar, K-Ar, Rb-Sr, and U-Pb methods in several laboratories in the US and Canada. Since both the ash beds and the tektites occur either at or very near the K-T boundary, as determined by diagnostic fossils, the tektites and the ash beds should be very nearly the same age, and they are (Table 2).

There are several important things to note about these results. First, the Cretaceous and Tertiary periods were defined by geologists in the early 1800s. The boundary between these periods (the K-T boundary) is marked by an abrupt change in fossils found in sedimentary rocks worldwide. Its exact location in the stratigraphic column at any locality has nothing to do with radiometric dating — it is located by careful study of the fossils and the rocks that contain them, and nothing more. Second, the radiometric age measurements, 187 of them, were made on 3 different minerals and on glass by 3 distinctly different dating methods (K-Ar and 40Ar/39Ar are technical variations that use the same parent-daughter decay scheme), each involving different elements with different half-lives. Furthermore, the dating was done in 6 different laboratories and the materials were collected from 5 different locations in the Western Hemisphere. And yet the results are the same within analytical error. If radiometric dating didn’t work then such beautifully consistent results would not be possible.

Dating of The Mt Vesuvius Eruption

In the early afternoon of August 24, 79 CE, Mt Vesuvius erupted violently, sending hot ash flows speeding down its flanks. These flows buried and destroyed Pompeii and other nearby Roman cities. We know the exact day of this eruption because Pliny the Younger carefully recorded the event. In 1997 a team of scientists from the Berkeley Geochronology Center and the University of Naples decided to see if the 40Ar/39Ar method of radiometric dating could accurately measure the age of this very young (by geological standards) volcanic material. They separated sanidine crystals from a sample of one of the ash flows. Incremental heating experiments on 12 samples of sanidine yielded 46 data points that resulted in an isochron age of 1925 94 years. The actual age of the flow in 1997 was 1918 years. Is this just a coincidence? No — it is the result of extremely careful analyses using a technique that works.

This is not the only dating study to be done on an historic lava flow. Two extensive studies done more than 25 years ago involved analyzing the isotopic composition of argon in such flows to determine if the source of the argon was atmospheric, as must be assumed in K-Ar dating (Dalrymple 1969, 26 flows; Krummenacher 1970, 19 flows). Both studies detected, in a few of the flows, deviations from atmospheric isotopic composition, most often in the form of excess 40Ar. The majority of flows, however, had no detectable excess 40Ar and thus gave correct ages as expected. Of the handful of flows that did contain excess 40Ar, only a few did so in significant amounts. The 122 BCE flow from Mt Etna, for example, gave an erroneous age of 0.25 0.08 Ma. Note, however, that even an error of 0.25 Ma would be insignificant in a 20 Ma flow with equivalent potassium content. Austin (1996) has documented excess 40Ar in the 1986 dacite flow from Mount St Helens, but the amounts are insufficient to produce significant errors in all but the youngest rocks.

The 79 CE Mt Vesuvius flow, the dating of which is described above, also contained excess 40Ar. The 40Ar/39Ar isochron method used by the Berkeley scientists, however, does not require any assumptions about the composition of the argon trapped in the rock when it formed — it may be atmospheric or any other composition for that matter. Thus any potential error due to excess 40Ar was eliminated by the use of this technique, which was not available when the studies by Dalrymple (1969) and Krummenacher (1970) were done.

Thus the large majority of historic lava flows that have been studied either give correct ages, as expected, or have quantities of excess radiogenic 40Ar that would be insignificant in all but the youngest rocks. The 40Ar/39Ar technique, which is now used instead of K-Ar methods for most studies, has the capability of automatically detecting, and in many instances correcting for, the presence of excess 40Ar, should it be present.

Summary

In this short paper I have briefly described 4 examples of radiometric dating studies where there is both internal and independent evidence that the results have yielded valid ages for significant geologic events. It is these studies, and the many more like them documented in the scientific literature, that the creationists need to address before they can discredit radiometric dating. Their odds of success are near zero. Even if against all odds they should succeed, it still would not prove that the Earth is young. Only when young-earth creationists produce convincing quantitative, scientific evidence that the earth is young will they be worth listening to on this important scientific matter.

Acknowledgments

I thank Chris Stassen and 2 anonymous reviewers for their thoughtful comments, which led to important improvements in the manuscript.

References

Alvarez W. T Rex and the Crater of Doom. Vintage Books, 1998.

Alvarez W, Asaro, F. An extraterrestrial impact. Scientific American 1990; 263 (4): 78–84.

Arndts R, Overn W. Isochrons. Bible-Science Newsletter 1981; 14 (4): 5–6.

Austin SA. Excess argon within mineral concentrates from the new dacite lava dome at Mount St Helens volcano. Creation Ex Nihlo Techncal Journal 1996; 10: 335–43.

Dalrymple GB. 40Ar/36Ar analyses of historic lava flows. Earth and Planetary Science Letters 1969; 6: 47–55.

Dalrymple GB. How old is the earth? A reply to scientific creationism. In: Awbrey F, Thwaites WM, editors. Evolutionists Confront Creationists, Proceedings of the 63rd Annual Meeting, Pacific Division, American Association for the Advancement of Science, vol 1, part 3. 1984. p 66–131.

Dalrymple GB. The Age of the Earth. Stanford, Stanford University Press, 1991.

Dalrymple GB, Izett GA, Snee LW, Obradovich JD. 40Ar/39Ar age spectra and total-fusion ages of tektites from Cretaceous-Tertiary boundary sedimentary rocks in the Beloc formation, Haiti. US Geological Survey Bulletin 2065. 1993.

Gill CH. A sufficient reason for false Rb-Sr isochrons. Creation Research Society Quarterly 1996; 33: 105–8.

Izett GA, Cobban WA, Dalrymple GB, Obradovich JD. 40Ar/39Ar age of the Manson impact structure, Iowa, and correlative impact ejecta in the Crow Creek Member of the Pierra Shale (Upper Cretaceous), South Dakota and Nebraska. Geological Society of America Bulletin 1998; 110: 361–76.

Krummenacher D. Isotopic composition of argon in modern surface volcanic rocks. Earth and Planetary Science Letters 8: 109–17.

Morris HM. Scientific Creationism. 2nd ed. San Diego (CA): Creation-Life Publishing, 1985.

Morris JD. The Young Earth. Colorado Springs (CO):Creation-Life Books, 1994.

Renne PR, Sharp WD, Deino AL, Orsi G, Civetta L. 40Ar/39Ar dating into the historical realm: Calibration against Pliny the Younger. Science, 1997; 277: 1279–80.

Rugg S, Austin SA. Evidence for rapid formation and failure of Pleistocene “lava dams” of the western Grand Canyon, Arizona. In: Walsh RE, editor. Proceedings of the Fourth International Conference on Creationism Pittsburgh: Creation Science Fellowship, 1998. p 475–86.

York D. In Search of Lost Time. Bristol (UK): Institute of Physics Publishing, 1997.

York D, Dalrymple, GB. Comments on a creationist’s irrelevant discussion of isochrons. Reports of the National Center for Science Education 2000; 20 (3): xx–xx.

Woodmorappe J. Radiometric geochronology reappraised. Creation Research Society Quarterly 1979; 16: 102–29, 147.

About the Author(s): 

G Brent Dalrymple
College of Oceanic & Atmospheric Sciences
Oregon State University
Corvallis OR 97331-5503

The Evolution Debate is About Honesty

Reports of the National Center for Science Education
Title: 
The Evolution Debate is About Honesty
Author(s): 
James Haught
Volume: 
20
Issue: 
3
Year: 
2000
Date: 
May–June
Page(s): 
33–35
This version might differ slightly from the print publication.
[James A Haught, editor of the Charleston (West Virginia) Gazette, was awarded a Clarion Award by the Association of Women in Communications in the category of editorial opinion in US newspapers under 100 000 circulation. Haught's editorials and columns defended the separation of church and state in a variety of ways, including outspoken opposition to recent attempts of creationists to have the Kanawha County school board advise teachers to teach the supposed evidence against evolution (see Karl D Fezer, "Juicy Fruit or Spearmint in West Virginia", RNCSE 2000; 20 [1-2]: 16-19). RNCSE is pleased to reprint one of the columns for which Haught received his well-deserved award.]

During a recent evolution showdown, a visiting "creation scientist" from California repeatedly challenged me to debate, because I support the teaching of evolution. A Charleston talk radio host blistered me on the air because I would not come on his show and quarrel with the creationist professor.

But I felt it would be silly for me to argue about his supernatural beliefs. After all, I would not debate a Scientologist who asserts that all human souls are "thetans" from another planet. And I would not quarrel with a Unification Church member's claim that Jesus appeared to Master Moon and told him to convert all people as "Moonies". And I would not dispute a Mormon's belief that Jesus visited prehistoric America. And so on, and so on.

Let them all believe whatever they want. It is pointless to go on radio shows and wrangle over mystical claims. However, such claims must not be imposed on captive children in government-owned schools. That is prohibited by the separation of church and state, a core principle in the First Amendment in America's Bill of Rights.

America's time-tested freedom of religion means that every group may worship however it wishes in its own private church, but it cannot use the power of government to push its beliefs on others. Therefore it was gratifying that the Kanawha County school board overwhelmingly rejected a proposal to let creationist teachers denounce evolution in class. Educated families owe thanks to 4 brave board members - Pete Thaw, Bill Raglin, Cheryle Hall and John Luoni - who withstood heavy pressure from a throng of fundamentalists.

To me, the whole issue hinges on honesty. Let me explain: Science, from a Latin word meaning knowledge, is simply a search for trustworthy facts. It is human intelligence at work. The process is honest, because every researcher's claim is challenged by other researchers. They test and retest by many methods, until a new idea fails or holds firm. (A researcher who falsifies data is a loathsome criminal in the eyes of fellow scientists.)

While some individual scientists are pig-headed, an entire field cannot be. Science goes where the evidence leads. Science is honest enough to admit mistakes. When new evidence shatters a previous assertion, the old belief is dropped or modified. No such setbacks have hit the theory of evolution.

After 140 years of research, virtually the entire scientific world now agrees that evolution is a fundamental aspect of nature. Complex animals and plants arose from earlier, simpler ones, over hundreds of millions of years. The fossil record shows it. Geological strata show it. Radioactive dating shows it. The incredible diversity of species, with variations in different locales, shows it. The uncanny similarity of organs, bones, fluids, and nerves in many animals shows it.

Evolution was proved when skimpy Indian maize was improved into today's nutritious corn. It was proved when drug-resistant bacteria grew from survivors of antibiotic treatment (survival of the fittest). ... It was proved by the clear fossil record that today's horse grew from a tiny precursor.

College biology books are filled with many more examples. All this is why evolution should be taught in public school classes along with astronomy, physics, chemistry, and other established sciences. However, a fringe of "creation scientists" - rigid religious zealots - contend that evolution never happened, because they think it disagrees with their literal reading of the Book of Genesis. These people are not objective about evidence: they reject anything that supports evolution and exaggerate anything that might concur with the Old Testament.

The visitor who challenged me to debate holds a doctorate in physical education and is listed as "an adjunct professor of physiology for the Institute for Creation Research" at Santee, California. He implied that he's motivated only by scientific interest - but his group's Web site is that of a church. It proclaims:
We believe God has raised up ICR to spearhead Biblical Christianity's defense against the godless dogma of evolutionary humanism. ... ICR is funded by God's people ... to proclaim God's truth about origins.
The Institute for Creation Research calls itself "a Christ-focused creation ministry". It says humans were made fully developed "in the 6 literal days of the creation week described in Genesis". It says this was a "relatively recent" event, and that fossils were formed during Noah's flood. It says anyone not saved "solely" by Jesus will "be consigned to the everlasting fire prepared for the devil and his angels". In other words, a billion Muslims, a billion Hindus, and hundreds of millions of Buddhists, Jews, Baha'is, Shintoists, and so on are doomed to fry forever, according to the ICR.

Well, all this is standard fundamentalism - but it is not science, and it would be illegal to teach it in public-school science classes, especially in cosmopolitan Charleston schools containing Muslim, Jewish, Hindu, Buddhist, and Baha'i children. Maybe you can see why I chose not to debate this mentality. Incidentally, the visiting professor offered $250 000 to anyone who can prove evolution. If this column wins the reward, I'll donate it to a real science institute.

[Reprinted from the Charleston Gazette, December 21, 1999, by permission.]

Review: Ride to Glory

Reports of the National Center for Science Education
Volume: 
20
Year: 
2000
Issue: 
3
Date: 
May–June
Page(s): 
36–37
Reviewer: 
Skip Evans
This version might differ slightly from the print publication.
Work under Review
Title: 
Ride to Glory: The People v. Charles Robert Darwin
Author(s): 
Warren LeRoi Jones
Brookeville (MD): General Title Inc., 1999. 416 pages.
As a matter of principle, I finish any book I start reading. Some books are easy to finish - anything by John Irving, and John Kennedy Toole's masterpiece A Confederacy of Dunces, for example. Others are more difficult. No book in recent memory, or distant memory for that matter, challenged this principle more than Ride to Glory by Warren LeRoi Johns, a lawyer and novelist wannabe.

Ride to Glory tells the story of one Joshua Chamberlain Ryan, a double PhD candidate in geology and paleontology, who has come to the conclusion, through a careful analysis of the evidence, that the earth is no more than 10 000 years old and that descent with modification is not a valid scientific theory, but rather a collection of "horse-and-buggy myths". Throughout the book Josh continually spouts standard young-earth creationist claptrap, and in fact, many of Johns's source for Josh's diatribes are well-known creationist organizations such as the Institute for Creation Research and anti-evolutionist authors such as Michael Denton.

The plot revolves around a mock trial in which the jury is asked to "render a simple Yes or No verdict to this key issue: 'Is evolution a fact?'"; the judge adds, "Your responsibility will be to judge Charles Robert Darwin guilty or not guilty of propagating fact-free science" (italics in original). The trial is staged by ace Hollywood promoter Pace Terhune. Josh is the star witness, aided by his best friend, law student JT Thomas. JT tosses fluff-ball questions at Josh, whose creationist rhetoric flows in italics, meticulously footnoted by Johns. Traci Kilburn, the new and beautiful love in Josh's life, is responsible for the completely unchallenging cross-examination.

The book fails as literature even more than it fails as science. The dialog is so contrived that it quickly became close to physically painful to read. Josh is described by one of his professors as speaking "the language of the streets". Apparently Johns has not heard any "language of the streets" since "blaxploitation" films were big in the 1970s. Much of the dialog strains at wit and then gets sprinkled with some "bros" to add that hip young attitude: "What's goin' on, Bro? You and the Montgomery County Sheriff are the only people cruisin' the scene at this outrageous hour. You oughta' be in church with the rest of the sinners... [Y]ou could use some of your granddad's preachin' to rid you of those lawyer-like flaws." Who in the world talks like that? Johns must have worn out the apostrophe on his keyboard.

The characters in the book are all completely 2-dimensional, without the slightest bit of the complexity and depth that draws us to literary characters. Joshua Chamberlain Ryan has a 4.0 grade-point average, and never a doubt about his convictions or beliefs enters his mind. Traci Kilburn and JT Thomas are unfailingly witty and charming. Dr Karl Striker, "flamboyant campus scientist" and Josh's archnemesis, comes across as gruff, authoritarian and, most importantly, unbending in his religiously dogmatic approach to Darwinism. In fact, the contrast between the supporters of evolution, Striker and his minions, and the upholders of truth, Josh and his buddies, is shallow and obvious to the point of boredom. Two of Striker's underlings turn out to be pathetically nefarious characters, a drug addict and a would-be murderer who attempts to kill Josh.

Josh Ryan appears virtually faultless, which makes him unreal and not the least bit sympathetic. Likewise, Traci and JT are cut from exactly the same mold, always equipped with snappy little comebacks for any situation. When we read about fictional characters, it is often more their faults than their superlative virtues that draw us to them, because we can relate to fallible characters - except for readers who happen to be perfect themselves; but I would imagine that that clientele is pretty small.

The plot is so predictable that I began wishing I had taken some speed reading courses. The reader is pummeled, page after page, with tiresome, strained dialog, and such an easily predictable plot that it is possible to anticipate the story line 10, or even 100, pages later. Each plot line proceeds mechanically and unswervingly so that the story wraps up at the end like a television sitcom.

There is not space here to go into the plot in any depth, but I feel pretty sure that after the first 50 pages or so any reader can guess how just about the whole thing will turn out. Traci will accept Josh's proposal of marriage; Josh will be united with his grandmother, although she dies trying to save his thoroughbred horse from a barn fire set by one of Striker's minions (who then dies in a minivan trying to escape the scene); Josh becomes a star after thoroughly refuting Darwin's theories in "Monkey II"; and JT is promised a spot at a major law firm upon his graduation from law school.

Though subtitled An American Novel, from my experience studying the former Soviet Union in depth, I would say that the book reads more like some kind of official propaganda. The absolute demarcation between the guys wearing the white hats and the guys wearing the black hats, and the complete lack of human conflict on any true level, drag the book to such a shallow level that it quickly runs aground; just getting to the end is a real chore.

By now you probably have the idea that I am not going to recommend that you rush right out and buy Ride to Glory, but if you do want to check out the story for yourself, I recommend just getting a copy of Jack Chick's notorious anti-evolution tract, Big Daddy. It could have easily served as Johns's first draft.

About the Author(s): 
Skip Evans has been active in theater for over 10 years, as actor, director, and playwright. He performed improvisational comedy in Atlanta, Georgia, from 1995 to 1998, and has written 5 full-length plays as well as numerous short stories and essays. His first play, The Psychopathic Librarian, was the Best New Play at Eola Theater Company in Orlando, Florida, 1994. He currently lives in New York City.

Review: Evolution

Reports of the National Center for Science Education
Volume: 
20
Year: 
2000
Issue: 
3
Date: 
May–June
Page(s): 
38–39
Reviewer: 
Karen Bartelt
This version might differ slightly from the print publication.
Work under Review
Title: 
Evolution
Author(s): 
Colin Patterson
Ithaca (NY): Cornell University Press, 1999. 153 pages.
In 1981, paleontologist Colin Patterson spoke at the American Museum of Natural History. Later he said that in his talk, "I put a case for [the] difficulties and problems with evolution, specifically in the field of systematics. I was too naïve and foolish to guess what might happen: the talk was taped by a creationist who passed the tape to [creationist] Luther Sunderland. ...I was putting a case for discussion, as I thought off the record, and was speaking only about systematics, a specialised field" (Fezer 1984: 5).

Snippets from this unauthorized taping (for which no authorized transcript exists; see Strahler 1987) have been making the rounds of anti-evolutionist publications since Luther Sunderland and Gary Parker's 1982 Impact article. They have popped up in many subsequent issues of ICR's Impact (for example, Buckna and Laidlaw 1996) and routinely appear in anti-evolutionist articles and web sites (for example, Lenard 2000). Patterson was also featured in a 1996 article in the journal Origins and Design (Nelson 1996), a venue devoted to "intelligent design theory", which included 9 of his quotations that supposedly manifest what Nelson calls Patterson's "agnosticism about evolution".

Fast forward to 1999; if ever he was, Patterson is agnostic about evolution no more. All opportunities for anti-evolutionist innuendo and misstatements are put to rest in the second edition of Evolution. Sadly, Patterson died 3 days after delivering the manuscript to the publisher; 2 of his colleagues (Peter Forey and James Mallet) did some minor revisions and final editing.

The book is a concise, lucid introduction to evolutionary biology for the layperson. Among the valuable resources is a discussion of molecular biology that contains references to 1996 and so is fairly up to date. The drawings and charts make the text easier for a nonspecialist to follow.

I really appreciated the discussion of hemoglobin. Patterson reports that 550 mutations of human hemoglobin have been described (including substitutions, deletions, and additions), and that 1 human in 2000 carries a mutant hemoglobin. The "Tak" and "Saverne" mutations add 10 amino acids each to the beta hemoglobin chain, while the "McKees Rocks" mutation shortens the same chain by 2 amino acids. This is a powerful argument against the anti-evolutionist mantra of "mutations are bad", because, as Patterson notes, "none inhibits development and most produce no detectable physical symptoms" (p 29).

Patterson also focuses on homology at the molecular level, especially as it applies to the evolution of hemoglobin. There is a good discussion of gene duplication, the relationship of the hemoglobin pseudogenes to the active genes, and some nice gene histories showing hemoglobin relationships among primates and other mammals. Patterson finds Motoo Kimura's neutral theory of evolution quite appealing and returns to it frequently. If one is looking for a pithy comment to counter anti-evolutionist claims, try Patterson's conclusion that "[I]n genetic terms we are hardly more distinct from chimpanzees than are subspecies in other groups of animals" (p 113).

Though an interesting introduction to evolutionary biology, the real strengths of this book are in its final chapters and preface, where Patterson explains his ideas about evolution and comments on creationism and (indirectly) on the 1981 taping of his talk. Clarifying his views on evolution in the preface to the second edition, Patterson says:
The knowledge in my first edition came from education and indoctrination; it was that neo-Darwinism is certainty. The knowledge in this second edition comes more from working things out for myself; it is that evolution is certainty. And part of the ignorance in the first edition concerned the difference between neo-Darwinism and evolution, whereas the ignorance in this edition is of the completeness of neo-Darwinism as an explanation of evolution ... I think that belief [shared ancestry] is now confirmed as completely as anything can be in the historical sciences ... [but] ... I am no longer certain that natural selection is the complete explanation...". (p vii).
Although Patterson considers the general theory of evolution ("evolution has occurred") to be a historical theory and hence "by some definitions" not a part of science because it deals with unrepeatable events, he acknowledges that it does have rules, does make general predictions, and is open to disproof. Furthermore, evolution has survived a series of severe tests unimaginable to Darwin - including its consistency with genetics, the universality of DNA, and "the evidence from DNA sequences of innumerable 'vestigial organs' at the molecular level" (p 117).

Patterson concludes, "[i]n terms of mechanism ... the neutral theory of molecular evolution is a scientific theory; it can be put into law-like form: changes in DNA that are less likely to be subject to natural selection occur more rapidly. This law is tested every time homologous DNA sequences are compared. ... But neutral theory assumes (or includes) [the] truth of the general theory - common ancestry or Darwin's 'descent with modification' - and 'misprints' shared between species, like the pseudogenes or reversed Alu sequences, are (to me) incontrovertible evidence of common descent" (p 119).

Creationism itself receives only a few pages, which include Patterson's response to the taping: "Because creationists lack scientific research to support such theories as a young earth ... a world-wide flood ... or separate ancestry for humans and apes, their common tactic is to attack evolution by hunting out debate or dissent among evolutionary biologists. ... I learned that one should think carefully about candor in argument (in publications, lectures, or correspondence) in case one was furnishing creationist campaigners with ammunition in the form of 'quotable quotes', often taken out of context" (p 122).

Perhaps the best audience for this book would be anti-evolutionists. Not only could they learn about the evidence for evolution at the molecular level, but they might be inspired to correct the inaccuracies about the late Dr Patterson that abound on their web sites.

References

Buckna D, Laidlaw D. Should evolution be immune from critical analysis in the science classroom? ICR Impact 1996; 282: i-iv. Accessed June 25, 2000.

Fezer K. Harper's comforts creationists. Creation/Evolution Newsletter 1984 Nov-Dec; 4 (6): 4-5.

Lenard R. Evolution is not science. 2000; available from . Accessed June 24, 2000.

Nelson P. Colin Patterson revisits his famous question about evolution. Origins and Design 1996; 17 (1): 5-8.

Strahler A. Science and Earth History. Buffalo (NY): Prometheus Books, 1987.

Sunderland L, Parker G. Evolution? Prominent scientist reconsiders. ICR Impact 1982; 108: i-iv. . Accessed June 25, 2000.