Evolution and the Origin of Life

1. Introduction: Evolution Defined
   
2. Is Evolution A Theory Or A Fact?
   
3. Evidence For Genetic Variability
   
4. Scientific Theory vs. Common Theory
   
5. Scientific Theory & Scientific Law
   
6. The Evidence For Evolution
   
7. Adaptive Radiation In Hawaiian Islands
   
8. Parallel & Convergent Evolution
   
9. Major Subdivisions Of Evolution
   
10. Faith & The Existence Of Coconut Pearls
    
11. Propositions For The Origin Of Life
    
12. Danger Of Imposing Non-Science Dogma
    
13. Origin Of Life By Probability Alone
    
14. Origin Of Magnificent Grand Canyon
    
15. True or False Summary Statements
    
16. Literature Cited In This Report

1  One of the problems in understanding evolution is that it may be defined in different ways. According to the Random House Webster's College Dictionary (1999), biological evolution is a change in the genetic makeup of a population from generation to generation. It may also be defined as the development of species or other groups of organisms (genera and families) from earlier forms by natural selection. Microevolution refers to changes at or below the species level, while macroevolution generally refers to large-scale changes over a long period of time resulting in new species.

2  In November 2004, suburban Atlanta biology textbooks included a warning sticker that said:

"This textbook contains material on evolution. Evolution is a theory, not a fact, regarding the origin of living things. This material should be approached with an open mind, studied carefully and critically considered."

3  On November 19, 2004, the Dover School Board of Pennsylvania passed a resolution requiring teachers to read a statement to students in 9th grade science classes endorsing intelligent design as an alternative explanation for the origin of life.

"The Pennsylvania Academic Standards require students to learn about Darwin's Theory of Evolution and eventually to take a standardized test of which evolution is a part. Because Darwin's Theory is a theory, it continues to be tested as new evidence is discovered. The Theory is not a fact. Gaps in the Theory exist for which there is no evidence. A theory is defined as a well-tested explanation that unifies a broad range of observations. Intelligent Design is an explanation of the origin of life that differs from Darwin's view. The reference book, Of Pandas and People, is available for students who might be interested in gaining an understanding of what Intelligent Design actually involves. With respect to any theory, students are encouraged to keep an open mind. The school leaves the discussion of the Origins of Life to individual students and their families. As a Standards-driven district, class instruction focuses upon preparing students to achieve proficiency on Standards-based assessments."

4  The resolution was challenged a year later in the United States federal courts: Case No. 04cv2688, "Tammy Kitzmiller et al v Dover Area School District." The plaintiffs successfully argued that intelligent design is a form of creationism, and that the school board policy thus violated the Establishment Clause of the First Amendment to the United States Constitution.

5  The argument whether evolution is a theory or a fact is an invalid comparison. Evolution is a scientific theory that has explained the factual evidence of scientists for more than a century. All interpretations of facts in science are provisional and subject to challenge. Under a strict definition, a scientific theory should not be called a "fact" even though it explains all known facts and has survived the test of time. There is always the possibility that a scientific theory will be updated or changed as new evidence is discovered. The theory of evolution assumes the existence of life and is directed to an explanation of how life evolved. It does not deal with the origin of life, and it does not presuppose the absence of a creator or God. Although the origin of life is often included in debates about evolution, it is a very different topic that does not have all the empirical evidence of biological evolution. Scientific explanations for the origin of life are more properly referred to as hypotheses rather than scientific theories. Intelligent design is a non-scientific argument or assertion that life "owes its origin to a master intellect." Please refer to Origin of Life later in this this discussion.

6  According to E.C. Scott (Evolution vs. Creationism, Univ. of Calif. Press, 2004), most people consider facts more important than hypotheses, theories and laws. In fact, they rank these terms in order of importance as follows: Facts-Laws-Theories-Hypotheses. Scientists rank these terms in the following order from most important to least important: Theories-Laws-Hypotheses-Facts. Facts are certainly not set in stone and are often changed in science. Consider the number of chromosomes in a human somatic cell. In the 1950s the number was determined to be 48. This fact was published in all biology textbooks. With better techniques in staining chromosomes, the number was later revised to 46, 23 from each parent. Disagreement on chromosome numbers still occurs to this day, particularly with plant species containing numerous chromosomes that often overlap each other making accurate counts very difficult. For as long as I can remember, Pluto has been listed as the ninth planet in our solar system. Recent studies of its orbital patterns and other factors indicate that Pluto is not a true planet compared with Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

7  There is compelling evidence to show that humans once had 24 pairs of chromosomes (2n = 48) like present-day great apes (orangutans, gorillas and chimpanzees). Like all other 23 chromosomes, chromosome #2 has a terminal genetic marker called a telomere. Telomeres shorten prior to chromosome replication and cell division. Shortened telomeres eventually signal the cell to stop dividing. In cancer cells, an enzyme called telomerase keeps telomeres at a constant length so that cancer cells keep on dividing over and over again. Chromosome #2 has a second telomere in the middle region, indicating that two chromosomes joined together end-to-end an became permanently fused into chromosome. The sister chromatids of a chromosome doublet are attached in a constricted region of the chromosome called the centromere. Each chromosome has a single centromere; however, chromosome #2 has two centromeres, further evidence that it represents two fused chromosome doublets, each with its own centromere.

8  Some biologists say that evolution is a scientific theory and a fact. According to T. Ryan Gregory of the Department of Integrative Biology, University of Guelph, Ontario, Canada (2007), the notion that species may change through time and that living organisms are related to one another through common descent is a fact. He also states that evolution is a well-established scientific theory. "That evolution is a theory in the proper scientific sense means that there is both a fact of evolution to be explained and a well-supported mechanistic framework to account for it. To claim that evolution is "just a theory" is to reveal both a profound ignorance of modern biological knowledge and a deep misunderstanding of the basic nature of science."

9  The eminent evolutionary biologist Ernst Mayr also considers evolution to be a fact. In his book What Evolution Is (2001), he gives the following explanation:

Is Evolution A Fact? "Evolution is not merely an idea, a theory, or a concept, but is the name of a process in nature, the occurence of which can be documented by mountains of evidence that nobody has been able to refute. Some of this evidence was summarized in Chapters 1-3. It is now actually misleading to refer to evolution as a theory, considering the massive evidence that has been discovered over the last 140 years documenting its existence. Evolution is no longer a theory, it is simply a fact."

10  The Working Group on Teaching Evolution, National Academy of Sciences (1998) defines a scientific theory as a well-substantiated explanation of some aspect of the natural world than can incorporate facts, laws, inferences, and tested hypotheses. Like "theory," the word "fact" has a different meaning in science than it does in common usage. A scientific fact is an observation that has been confirmed over and over. However, observations are gathered by our senses, which can never be trusted entirely. Observations also can change with better technologies or with better ways of looking at data. Please refer to paragraph 6 which discusses the erroneous human chromosome number of 48 and the planet Pluto. "Ironically, facts is science often are more susceptible to change than theories--which is one reason why the word "fact" is not much used in science."

11  Eugenie C. Scott of the National Center For Science Education (2001) defines "facts" of evolution in the following paragraph:

"From the standpoint of philosophy of science, the "facts of evolution" are things like the anatomical structural homologies such as the tetrapod forelimb, or the biochemical homologies of cross species protein and DNA comparisons, or the biogeograpgical distributions of plants and animals. The "facts of evolution" are observations, confirmed over and over, such as the presence and/or absence of particular fossils in particular strata of the geologic column (one never finds mammals in the Devonian, for example). From these confirmed observations we develop an explanation, an inference, that what explains all of these facts is that species have had histories, and that descent with modification has taken place. Evolution is thus a theory, and one of the most powerful theories in science."

12  All of these discussions of whether evolution is a theory or a fact depend on how the terms "theory" and "fact" are defined. The "fact" that living organisms change with time is undeniable; however, in my opinion, evolution is best explained as a well-established scientific theory based on numerous facts. The position of Wayne's Word in teaching evolution is summarized by the Steering Committee on Science and Creationism, National Academy of Sciences (1999):

"The contention that evolution should be taught as a "theory, not as a fact" confuses the common use of these words with the scientific use. In science, theories do not turn into facts through the accumulation of evidence. Rather, theories are the end points of science. They are understandings that develop from extensive observation, experimentation, and creative reflection. They incorporate a large body of scientific facts, laws, tested hypotheses, and logical inferences. In a sense, evolution is one of the strongest and most useful scientific theories we have."

13  In order to have changes in populations of organisms it is necessary to have a source for the genetic variability. There are at least five sources of genetic variability in populations: (1) DNA mutations or changes in existing genes and the formation of new genes. (2) Reshuffling of chromosomes and genes during meiosis and sexual reproduction, including crossing over and transposons. (3) Natural selection for favorable traits, and selection against undesirable genes. (4) Interbreeding between genetically different populations, including emigration and immigration. (5) Genetic drift in relatively small, isolated populations.

14  There is ample evidence from field observations and DNA studies in laboratories to show that genetic variation occurs within populations of plants and animals. These are undeniable facts. The degree of variability is reflected in different levels of organization (taxonomic hierarchies), such as families, genera and species. DNA variations can be induced in the laboratory using mutagenic agents, such as strong chemical oxidizing agents and high energy radiation. Genetic variation can be readily observed in pathogenic bacteria that defy medical science by rapidly changing into new forms that are resistant to the latest antibiotics. HIV disguises itself from our highly evolved immune system and even acquires resistance to antiviral drugs, such as AZT. In fact, our war on pathogenic microbes has accelerated the process of microevolution in these organisms. Genetic variability is the raw material for this evolution. A thorough understanding of the genetics and evolution of pathogenic microorganisms may be crucial to the survival of the human race.

15  The primary explanation for the astonishing variety of life on earth is the amazing genetic molecule called DNA (deoxyribonucleic acid). DNA has been metaphorically described as a long, twisted ladder with literally millions of rungs composed of the base pairs: adenine (A) with thymine (T) and guanine (G) with cytosine(C). Each rung has 4 possible arrangements: A-T, T-A, C-G, and G-C. A DNA molecule with five billion base pairs has 4^{5,000,000,000} or 10^{3,000,000,000} different possible base sequences. This astronomical number has three billion digits and would fill about one million pages on a computer printout (12 cpi). This incredible number helps to explain the enormous diversity of life forms, from viruses and bacteria to complex plants and people, all genetically programmed by DNA. Flowering plants alone range from tiny wolffias less than one millimeter long to huge eucalyptus trees over 100 meters tall. The potential variability and mutability of DNA make it a perfect mechanism for evolution.

16  A scientific theory is a testable explanation about the cause or causes of a broad range of related phenomena. It remains open to tests, revision, and tentative acceptance or rejection. It should not be confused with a common layman theory or proposition that has not been scrutinized by the scientific method. In the scientific method, a hypothesis or tentative explanation is formulated to explain an observation or phenomenon. This is a good example of inductive reasoning where a general conclusion (hypothesis) is based on specific observations or data. Then an attempt is made to prove or disprove the hypothesis through detailed research and experimentation. Successful results by one scientist does not automatically turn a hypothesis into a theory. "One scientist cannot create a scientific theory; he or she can only create a hypothesis." Only after repeated tests by other scientists who arrive at similar conclusions does a hypothesis become a scientific theory. Evolution is not merely a common theory or "only a theory" as some people state in their commentaries. It is a scientific theory based on more than a century of research by thousands of dedicated scientists from throughout the world.

17  Biological evolution has considerable empirical evidence, and it is testable and verifiable. It fits the definition of a true scientific theory. Under a strict definition, a scientific theory should not be called a "fact" even though it explains all known facts and has survived the test of time (more than a century in the case of evolution). There is always the possibility that a scientific theory will be updated or changed as new evidence is discovered. The sticker placed in biology textbooks in Atlanta is poorly worded. It implies that evolution is just another "common theory," a tentative statement that attempts to explain something without any factual proof. A common theory has a popular meaning, which is roughly equivalent to an "educated guess" or "hunch." The label should say "scientific theory" rather than theory. In addition, the dichotomous comparison of a scientific theory with the word "fact" is incorrect.

18  As stated above, all interpretations of facts in science are provisional and subject to challenge. Physicists never refer to any theory as a "fact," and always leave open the possibility that any theory will be found to be incomplete or needing revision, even though it fits all known facts and has passed all tests so far. It is still Einstein's theory of relativity, even though it is probably as close to a fact as anyone can get in science. It has been tested every day in many ways and has survived. Some day we may find a more complete theory that explains and predicts relativity even better than Einstein's theory. The noun "theory" associated with time-tested explanations, such as evolution, relativity and plate tectonics, should be modified by the adjective "scientific" in order to distinguish it from a "common" or "layman" theory that is essentially a tentative explanation or untested hypothesis. In fact, it would be better to capitalize the word theory when it refers to a scientific theory. [For example, gram calories and dietary Calories are spelled the same, except that a dieter's Calorie is capitalized and actually refers to a kilocalorie!]

19  It should be noted here that a hypothesis does not always become a scientific theory. Here is an example: A botanist discovers a wildflower population that appears different from all other known species of a particular genus. His hypothesis states that this is a new (undecribed) species unknown to science. To prove this hypothesis it is necessary to collect numerous detailed measurements of the floral and vegetative parts and to conduct an extensive search of the literature and herbaria. A type specimen (holotype) of the plant is deposited in an internationally recognized herbarium. Duplicated specimens (isotypes) are deposited in other herbaria. The hypothesis is confirmed by statistical analysis of the data, including PCA (principal components analysis). The results are published in a peer-reviewed botanical journal. Generally, this hypothesis is not elevated to the level of a scientific theory. It can be reviewed by another botanist who may accept or reject the species status, perhaps by performing additional tests, such as DNA sequencing. This was essentially the method used by this author in coauthoring a new species of Brodiaea in 2007 named Brodiaea santarosae; however, in our particular case, the hypothesis for a new species came after our preliminary statistical investigation.

20  As I stated previously, the Working Group on Teaching Evolution, National Academy of Sciences (1998) defines a scientific theory as a well-substantiated explanation of some aspect of the natural world than can incorporate facts, laws, inferences, and tested hypotheses. They define a scientific law as a descriptive generalization about how some aspect of the natural world behaves under stated circumstances. Laws can be very useful in supporting hypotheses and theories, but like all elements of science they can be altered with new information and observations. Scientific theories and scientific laws are both derived from carefully formulated hypotheses that have been scrutinized and repeatedly tested by scientists. In general, they are both accepted to be true by the scientific community and they are both used to make predictions of events. The notion that scientific theories eventually become laws is incorrect. Scientific theories are generally more complex and dynamic than scientific laws; they have many components, and may be changed as the body of available experimental data and analysis develops. In addition, scientific theories explain a whole series of related phenomena. Examples of scientific theories include the chaos theory in mathematics, the theory of relativity in physics, and the theory of plate tectonics and continental drift in geology.

21  Scientific laws are strictly empirical and explain a single action or set of actions. They can sometimes be expressed in terms of a single mathematical equation. Examples of scientific laws include the laws of thermodynamics, Newton's law of gravity, Hook's law of elasticity, Ohm's law, and the gas laws (Boyle's law and Charles' law). Scientific laws may be components of scientific theories. For example, Newton's law of gravity is contained within Einstein's theory of relativity. Mendel's laws of segregation and independent assortment refer to specific mechanisms of the inheritance of genes. They were once hypotheses used by Gregor Mendel in 1865 to explain the inheritance of specific traits in garden peas, such as round vs. wrinkled and yellow vs. green peas. His original hypothesis explained the observed 9:3:3:1 ratios obtained from his dihybrid crosses. Mendel's laws are essential components of the modern theory of evolution; however, there are exceptions to these laws. When Mendel completed his research on genetic crosses with garden peas, he assumed that the individual traits were assorted independently of each other. One of his hypotheses became known as the Law of Independent Assortment. Today we can explain this law because the traits Mendel studied just happened to occur on separate chromosomes. Since the garden pea has 7 pairs of chromosomes, it is obvious that all the hundreds of genes in peas cannot occur independently of each other, and must be located on 7 pairs of homologous chromosomes. Depending on the exact genes you are studying, chromosomal linkage may result in ratios of offspring that are far different from the 9:3:3:1 predicted by Mendel. Laws and theories are the foundations of scientific knowledge; together they explain our complex natural world. They can be modified or changed as more information is available.

22  In 1908 English mathematician Godfrey Hardy and German physicist Wilheim Weinberg independently came up with an algebraic expression that describes how genotype frequencies in populations are related to allele frequencies. Known as the Hardy-Weinberg Law, it states that gene frequencies will remain constant generation after generation in large, randomly-mating populations. Although it is a law, it is only applicable under a strict set of conditions, including no mutations, no selection, no migrations between populations (immigration and emigration), and no genetic drift. In a 2-allele system, such as round and wrinkled peas, it is based on the square of a binomial (A + B). In a 3-allele system, such as the A-B-O blood types, it is based on the square of a trinomial (A + B + O). Although it is beyond the scope of this discussion, the Hardy-Weinberg Law is useful for studies in population genetics, particularly the determination of genotype frequencies in populations.

23  A fascinating article about evidence for evolution was written by David Quammen in the November 2004 issue of National Geographic. Evidence for evolution comes from many disciplines, including paleontology, biogeography, anatomy, embryology, physiology, biochemistry and cladistical analyses. In the latter discipline, computers create elaborate phylogenetic trees or cladograms from DNA sequences containing thousands of base pairs. The cladogram "trees" are organized from the most primitive organisms to the most advanced. The number of shared characteristics between any one species and another indicates how recently these two species have diverged from a shared lineage. Sometimes the cladograms fit the existing models based on fossil evidence and sometimes they do not. Whale paleontologist Peter D. Gingerich collected fossil specimens of early whales from remote areas of Egypt and Pakistan. His research traced the ancestry of whales back to a group of Eocene carnivorous mammals called mesonychids. Evidence from DNA comparisons suggests that whales descended from artiodactyls (even-toed, hooved mammals, such as antelopes, pigs and hippos). Then in 2000, a 47 million-year-old anklebone (astragalus) from a four-legged whale was discovered in Pakistan. This bone closely matched the homologous anklebone in an artiodactyl. The biochemists were right, whales are indeed related to hippos and antelopes!

24  In 2006, a team of scientists, including Edward B. Daeschler, Neil H. Shubin, and Farish A. Jenkins, Jr., unearthed an extinct fossil fish in the Canadian Arctic that dates back to the Devonian Period (360 million years ago). Their discovery appeared in the journal Nature 440 (6 April 2006: 757-763. The fossil fish is named Tiktaalik roseae. This animal has the characteristics of a fish, including gills and scales, but also has the flattened head of a small crocodile and unusual fins used for walking on land. Its fins have thin bones for paddling like most fishes, but they also have sturdy interior bones that would have allowed Tiktaalik to prop itself up in shallow water and use its limbs for support as most four-legged animals do. This remarkable fossil is truly a "missing link," an evolutionary transition between swimming fish and their descendents, a major phylogenetic branch (clade) giving rise to all four-legged vertebrates (tetrapods), including amphibians, dinosaurs, birds, and mammals.

25  Although cladograms are generated from comparative DNA samples, some are produced repeatedly and have higher "bootstrap" values. Cladograms with the highest bootstrap values are considered the most accurate. For example, if one thousand cladogram "trees" are generated from a comparative DNA sample and the same pattern comes out 900 times, this cladogram would have a bootstrap value of 90 percent. Evolution is a scientific theory because it is based on an abundance of empirical data, even though the precise mechanisms remain open to tests, revision, and tentative acceptance or rejection. There is substantial factual evidence to show that the genetic makeup of populations changes from generation to generation, and that these genetic changes are reflected in a bewildering array of different species of plants and animals. The following link shows cladograms which are remarkably similar to the original model proposed by Dr. Elias Landolt based on detailed morphological studies of this interesting plant family.

26  The earliest fossils of flowering plants date back approximately 130 million years, to a time when dinosaurs walked the earth. Exactly which ancestral seed plants gave rise to the flowering plants has been a hotly debated topic for more than a century. In fact, in a letter to a friend, Charles Darwin referred to the sudden appearance of flowering plants in the fossil record as "an abominable mystery." Grasses are considered relatively advanced flowering plants, and most macrofossils and pollen from grasses appear long after the demise of dinosaurs at the end of the Cretaceous Period (65 million years ago). Dioramas in museums have long depicted large sauropod dinosaurs grazing on conifers, cycads and ferns in landscapes without grasses. In the November 18 issue of Science, Caroline Strömberg of the Swedish Museum of Natural History and her Indian colleagues Vandana Prasad, Habib Alimohammadian and Ashok Sahni report phytoliths from grasses in the fossilized dung of sauropods that lived in central India about 65 to 71 million years ago.

27  Phytoliths are microscopic silica bodies found inside the cells of stems and leaves of grasses and other plants. Depending on the species of plant, they range from 5 to 100 micrometers in length. Because they are made of a crystalline form of silica called opal, they are very durable and retain their characteristic shapes over millions of years. Like microscopic pollen grains and diatoms, the phytoliths remain perfectly preserved in spaces between soil particles. Different genera of grasses have phytoliths with unique shapes, including square, rectangular, oblong, bilobed, wavy with undulate margins, and butterfly-shaped. Grasses belonging to the subfamily Panicoideae typically have phytoliths that are shaped like a dumb-bell. I examined the leaf blade of crabgrass (Digitaria sanguinalis), a member of the Panicoideae, and the phytoliths are indeed shaped like a dumb-bell.

28  It is remarkable how much information has been determined about the distant geologic past with new and improved methods of chemical analysis and sophisticated digital instruments. Each day the scientific theory of evolution is becoming more complete, as scientists uncover new facts and piece them together like a complex jigsaw puzzle.

silver sword

7. Adaptive Radiation On The         Hawaiian Archipelago

alulu

29  The Hawaiian archipelago has been isolated from continental land masses during the past 30 million years, and yet the 1,000 species of indigenous Hawaiian angiosperms are believed to stem from natural introduction by long-distance dispersal of 280 ancestral plant colonists (Manual of the Flowering Plants of Hawaii by Wagner, W.L., Herbst, D.R. and S.H. Sohmer, 1990). It appears that seeds were carried thousands of miles to these islands, possibly by rafting or within protective capsules and pods. For example, an ancestral California tarweed of the sunflower family (Asteraceae) traveled at least 3,000 miles to the Hawaiian Islands where it gave rise to a remarkable group of endemics known as the "Silver Sword Alliance." The small seeds from ancestral members of the lobelia family (Campanulaceae) also reached these islands from the American mainland giving rise to an unusual group of endemic Hawaiian lobelioids. This phenomenon where ancestral species colonize a new habitat and evolve into different species is called adaptive radiation. The new species evolve in response to different selection pressures that enable them to fill unique ecological niches. The story of Darwin's Finches on the Galapagos Islands is a classic example of adaptive radiation. The Hawaiian silver swords and lobelioids are truly unusual in appearance. They are strikingly different in appearance compared with California tarweeds or members of the lobelia family on the mainland of North and South America. Their taxonomic affinities with ancestral species are based on chromosome comparisons, hybridization studies and comparative chloroplast DNA. The unscientific hypothesis that these bizarre plants were placed here in their present form by a creator is untenable.

30  Sometimes evolutionary change follows a common pathway in two or more unrelated or distantly-related organisms because of similar environmental pressures. It culminates in unrelated organisms with similar morphological characteristics even though they did not have a common ancestor. This phenomenon is called parallel evolution. There are many examples of parallel evolution in plants, including distantly-related plant families that have evolved from an autotrophic to a parasitic mode of existence. Some plants have evolved independently into a mycotrophic mode of existence where they obtain nutrients from mycorrhizal soil fungi, which in turn, are parasitic on the roots of nearby forest trees and shrubs. Photosynthetic pathways, such as CAM (crassulacean acid metabolism) and C-4 photosynthesis, have also evolved independently in distantly-related plant families. When parallel evolution results in organisms that greatly resemble each other in overall appearance and possess similar adaptations, this is called convergent evolution. It should be noted here that some authors use these two terms interchangeably.

31  Another example of parallel evolution is the appearance of xylem vessels in the vascular tissues of very distantly-related plants, such as Ephedra in the gymnospermous division Gnetophyta and flowering plants in the angiospermous division Anthophyta. In addition, species of Ephedra have double fertilization, where two sperm are involved in the fertilization process. Double fertilization was once thought to be a strictly angiosperm characteristic. Some older references have suggested that the Gnetophyta may represent a "missing link" in the evolution of flowering plants, but others say that vessels and double fertilization are examples of parallel evolution. Considering all their amazing similarities, it seems quite plausible that the Gnetophyta and angiosperms may have shared a common ancestor. If the latter hypothesis is correct, then the appearance of vessels and double fertilization in these two groups of vascular plants would not be parallel evolution.

32  The laurel family (Lauraceae) includes about 2,000 species of trees and shrubs in 50 genera. Familiar genera in the family include Cinnamomum (cinnamon and camphor), Laurus (European bay), Umbellularia (California bay), Sassafras and Persea (avocado). One genus in this family (Cassytha) has broken away from the other trees and shrubs and has evolved into a leafless, twining parasitic herb that absorbs nutrients from it host by a specialized modified root called a haustorium. The distantly-unrelated morning-glory family (Convolvulaceae) also has about 50 genera of trees, shrubs and vines. Like the laurel family, one of these genera (Cuscuta) has evolved into a twining, leafless parasitic herb with a specialized organ of absorption (haustorium). Some botanists place this genus in its own family, the Cuscutaceae, although the floral morphology is very similar to some members of the Convolvulaceae. Both Cassytha and Cuscuta are remarkably similar in appearance, even though they live in different parts of the world and do not share a common ancestor. The radical modification of these two unrelated plants into specialized parasites is a marvelous example of convergent evolution.

34  In Australia there are many examples of marsupials that resemble our North American placental mammals. For example, Australia's flying phalanger is remarkably similar to the North American flying squirrel. Both tree-dwelling mammals glide through the air with their parachute-like fold of furry skin between the front and hind legs. These are excellent examples of convergent evolution.

35  The supplemental biology text Of Pandas and People (2nd. Edition, 2004) that is endorsed by advocates of intelligent design includes a different definition for parallel evolution. According to the authors of the latter text, "If two organisms are judged to be related through a "recent" common ancestor, their similarities are said to result from parallel evolution." They also state that if the ancestor is distantly related, convergent evolution has occurred. This definition of parallel evolution is incorrect. If two organisms are derived from a common ancestor, then the terms parallel and convergent evolution are not applicable.

36  The terms homology and homoplasy may be easier to understand. Homology refers to similarity due to a common ancestor. Characteristics derived from a common ancestor are termed homologous. Homologous organs are similar in structure and embryonic origin but are not necessarily similar in function. Cactus spines are homologous to bud scales of an axillary bud. Seed-bearing carpels of flowering plants are homologous to leaves because of their similarity in form, anatomy and development. Homoplasy (ho-MOP-la-see) means similarity due to independent origin that is not from a common ancestor. Homoplastic characteristics, such as the spines of cacti and stem-succulent euphorbias, evolved independently from each other. Cactus spines arise from an axillary growth center called an areole. Euphorbia spines are derived from modified stipules. Homoplasy includes parallel and convergent evolution. Similarity of structure in unrelated or distantly-related organisms is often the result of similar evolutionary pathways under similar environmental conditions. Using the term homoplasy avoids the confusing distinction between parallel and convergent evolution.

37  The recently discovered cerambycid beetle Onychocerus albitarsis in Peru is truly one of the most remarkable examples of convergent evolution (homoplasy). It is described by A. Berkov, N. Rodriguez and P. Centeno in Naturwissenschaften Vol. 95, March 2008. Venom-injecting structures have arisen independently in unrelated arthropods, including spiders, centipedes and antlions. The venom is injected through hollow fangs (poison jaws), or in the case of centipedes, through modified forelegs. Among insects only wasps, bees and ants of the order Hymenoptera are known to possess true stingers. Microscopic examination of the newly discovered beetle has revealed that the tip of each antenna is truly a stinging device. In fact, Mr. Centeno discovered this fact first hand. As he grabbed the beetle, the insect jerked back its antennae and pricked his finger, which swelled as if stung by a bee. This is the first example of a stinger in the enormous beetle order Coleoptera.

38  The terminal antennal segment of Onychocerus albitarsis has two pores opening into channels leading to the pointed tip through which the venom is delivered. The delivery system is almost identical to that found in the stinger of certain scorpions. Since beetles and scorpions belong to entirely different arthropod orders and are only distantly related, this is a dramatic example of homoplasy: similarity due to independent origin that is not from a common ancestor. In this case the homoplastic characteristics (stinging devices) evolved independently from each other. Although the article in Naturwissenschaften uses the term "convergent evolution," one might argue that this is "parallel evolution." The term homoplasy makes this confusing distinction unnecessary.

Tail of Arizona desert scorpion (Hadrurus arizonensis)

Beetles, Stinging Organs, and Fang-Like Jaws The Diverse Order Of Beetles The Stinging Tail Of Scorpions The Fang-like Jaws Of Antlions The Fangs Of A Jumping Spider   Fang-like Forelegs Of Centipedes

39  In Chapter 6 of The Origin of Species, Charles Darwin expressed concern over how a complex organ, such as the eye, could evolve by natural selection. "... if numerous gradations from a perfect and complex eye to one very imperfect and simple, each grade being useful to its possessor, can be shown to exist; if further, the eye does vary ever so slightly, and the variations be inherited, which is certainly the case; and if any variation or modification in the organ be ever useful to an animal under changing conditions of life, then the difficulty of believing that a perfect and complex eye could be formed by natural selection, though insuperable by our imagination, can hardly be considered real." In fact, some creationists have taken the previous quotation out of context and used it in their argument against evolution be means of natural selection. Like the wings of birds, bats and insects, many biologists have used the term homoplasy to explain the independent origin of eyes in diverse groups of animals. In fact, because the anatomy of the camera-like vertebrate eye is so different from the simple eyes of limpets and the compound eyes of insects, scientists thought that eyes evolved independently numerous times.

40  Homoplasy may not adequately explain the origin of eyes in different animal phyla. Recent evidence indicates that eye-forming genes evolved only once in a distant ancestor. These primordial eye genes provided the ancestor of present-day animals with photoreceptor cells and the ability to detect light. Mutations and evolution brought other genes under the control of these primordial genes, and together they produced a variety of eyes from simple to complex. With photoreceptor cells at the base of a simple eye cavity, mutations and modifications leading to a more advanced eye are plausible. An explanation for the development of eyes in different present-day species of mollusks is presented by M.F. Land and D.-E. Nilsson (2002) in their book Animal Eyes. This fascinating hypothesis is summarized by C. Zimmer in the November 2006 National Geographic.

41  All of the following mollusks share a common ancestral trait: A layer of light-sensitive cells at the base of an eye cavity. In the limpet, this layer of photosensitive cells in a shallow depression can detect light but the eye cannot produce an image. Beyrich's slit shell has a deeper eyecup that provides more information about the direction of the light source, but creates no image. In the chambered nautilis, a small gap at the top of the eye cavity acts as a pinhole pupil, focusing light on photosensitive cells that serve as a rudimentary retina. In Murex, fluid in a fully enclosed eye cavity functions as a primitive lens, focusing light on the retina to create a slightly sharper image. In the common octopus, advanced vision is created by a more complex eye equipped with a protective cornea, colored iris, and focusing lens.

42  The term evolution is very broad and has numerous subdivisions, particularly explanations for the mechanisms of change. Charles Darwin's "On the Origin of Species by Means of Natural Selection" was a testable scientific hypothesis that explained one mechanism of evolution called natural selection. Alfred R. Wallace also came up with this hypothesis at the same time period. In fact, Darwin and Wallace coauthored a paper on natural selection for Journal of the Proceedings of the Linnean Society in 1858. The following year, Darwin published his Origin of Species and his name is usually associated with the theory of evolution. Natural selection may explain some aspects of evolution; however, there are other explanations. Punctuated equilibrium was proposed by Niles Eldredge and Steven Jay Gould in the 1970s. It postulates that speciation may occur relatively quickly in geologic time, with long periods of little change (equilibria) in between. Punctuated equilibrium explains the evolutionary patterns of species as observed in the fossil record, particularly the sudden appearance of new species in a geologically short period of time. Another scientific hypothesis known as symbiogenesis, is described in the book entitled Acquiring Genomes: A Theory of the Origins of Species by L. Margulis and D. Sagan (2002). According to the authors, genomic mergers are a major source of genetic variability leading to the evolution of species. Instead of relying on the hit-or-miss method of random mutations, symbiogenesis provides advantageous genetic combinations through the fusion of entire genomes from two or more organisms. This phenomenon may have been a major factor in the evolution of land plants from lichen-like ancestors. In 1981, Lynn Margulis also proposed the endosymbiont hypothesis to explain the origin of organelles within eukaryotic cells. According to endosymbiosis, cellular organelles (mitochondria and chloroplasts) originated from bacteria and cyanobacteria that became incorporated within living cells. When these original hypotheses have been repeatedly tested and scrutinized by different scientists, they may become scientific theories.

43  Both Darwin and Wallace are credited with the scientific hypothesis of evolution by means of natural selection. This hypothesis has been tested repeatedly by scientists during the past century and it is now elevated to the status of a scientific theory. Our knowledge of the evolution of life on this planet has grown considerably during the past 147 years since the time of Darwin. In fact, the term "Darwinist" repeatedly used in the intelligent design textbook Of Pandas and People is misleading. Does Darwinist refer to one who believes in the teachings of Darwin, or one that follows the modern scientific theory of evolution that encompasses many new concepts since the time of Darwin? The latter interpretation of evolution includes substantial information from the fields of genetics and molecular biology and is often referred to as neoDarwinism.

45  Religious debates over the origin of life are often false dichotomous arguments. If the scientific explanation is not adequate then the alternative argument for creation must be true. The problem here is that this debate is not limited to two alternative arguments. There are several scientific hypotheses for the origin of life and numerous explanations for supernatural creation throughout the world. In false dichotomous arguments, if one side is wrong this does not mean that the other side is correct. In true dichotomous arguments there are only two choices. If one side is false then the other side must be true. For example, in a dichotomous key to the duckweed family, one statement says that roots are present, while a second statement says that roots are absent. Only one of these statements is true regarding the duckweed species you are trying to identify.

46  There are literally thousands of non-scientific theories proposed for the origin of life, including intelligent design. Supernatural arguments for the origin of life are not scientific theories because they have no empirical evidence and cannot be tested or proven. They are based on faith in a creator (God). Advocates of intelligent design are very careful not to mention God as the designer. If the "designer" is not God, then is it an intelligent being from another galaxy? Advocates of intelligent design also argue that their "theory" has been tested and the results published in reputable, peer-reviewed scientific journals, but this is simply not the case. In 2004, an Intelligent Design article was accepted by the editor of Proceedings of the Biological Society of Washington without the approval of the Society's governing council. The 250 indignant members of this Society vehemently protested its publication. See "Creationism's Holy Grail: The Intelligent Design of a Peer-Reviewed Paper" by Robert Weitzel in (Skeptic Volume 11 (Number 4) 2005, pages 66-69. Although Charles Darwin mentioned a Creator in some editions of his Origin of Species, there is considerable speculation regarding his religious convictions. In a letter to Mr. J. Fordyce (1879) Darwin wrote: "... In my most extreme fluctuations I have never been an Atheist in the sense of denying the existence of God. I think that generally (and more and more as I grow older), but not always, that an Agnostic would be the most correct description of my state of mind." For more information about Darwin's religious beliefs, please refer to Finding Darwin's God by Kenneth R. Miller, HarperCollins, 1999.

47  The development of life from self-replicating organic molecules in the original "primordial soup" is a scientific hypothesis called biopoiesis. Scientists have created the molecular building blocks of life from gasses in a primitive earth atmosphere. They have also created what appear to be the precursors of cells; however, the precise mechanism and biochemical pathway for biopoiesis remain hypothetical. If one hypothesis does not adequately explain the origin of life, this does not mean that an alternative hypothesis is necessarily true. In fact, there are several hypotheses for the origin of life on earth, including an extraterrestrial origin. One of these is called the panspermia hypothesis which states that the earth was "seeded" by extraterrestrial prokaryotic cells similar to archaebacteria that were carried to earth by meteors. Under a strict definition, a hypothesis must be testable and verifiable before it becomes a scientific theory. Will a scientific theory be developed to explain the origin of life? Only time will tell.

48  Advocates of intelligent design would like to see their dogma taught alongside evolution in science courses. As I have stated in this report, intelligent design is not a scientific theory. It is not based on empirical evidence and cannot be tested or proven. It is dangerous to impose non-scientific dogma in science courses. One case in point is the teaching of acquired characteristics in the Soviet Union between 1948 and 1964. This hypothesis was proposed by the French biologist Jean-Baptiste de Lamarck in the early 1800s, and was actually proposed thousands of years earlier by Greek scholars. According to acquired characteristics, the environment can bring about inherited change. One classic example given by Lamarck is that the long neck of the giraffe developed over time because animals stretched their necks to browse high in trees and then passed on the propensity for a longer neck to their offspring. Although the environment is a factor in evolution, the mechanism of acquired characteristics has been thoroughly disproved during the last century: Phenotypic changes acquired during an organism's lifetime do not result in genetic changes that can be passed to subsequent generations. Potential gene-bearing gametes are set aside in the form of mother cells (oocytes and spermatocytes) early in an animal's embryonic development. The long neck of the giraffe is explained by genetic variabilty and selection for longer-necked offspring over thousands of generations. By the mid 1800s both Charles Darwin and Alfred Russel Wallace independently came up with their hypotheses of "survival of the fittest" to explain the origin of species by natural selection; but it was the Austrian Monk Gregor Mendel who in 1865 first described a mechanism to explain variability and the transmission of traits from parents to offspring. The story behind the teaching of acquired characteristics in the Soviet Union is a good example of why politics and religion should not interfere with scientific research.

49  In 1948, a decree of the Presidium of the Soviet Academy of Sciences appeared in Pravda. It stated that communists must teach and say that acquired characteristics are inherited. All research in agriculture and biology was controlled by Trofim Lysenko, the "dictator of genetic research." Refusal to follow acquired characteristics resulted in the dismissal, exile and execution of a number of Russian geneticists. During the late 1940s and 1950s, the Soviet Union fell behind the rest of the world in genetics research and there was a gradual failure in Soviet agriculture. Shortly after the downfall of Nikita Kruschev in 1964, Lysenko was dismissed from his administrative position. Soviet research in acquired characteristics was exposed as a fraud and the translation of western textbooks containing Mendelian genetics was ordered. The imposition of non-scientific dogma in the Soviet Union for a period of almost two decades resulted in a missing generation of trained geneticists. Politics and religion should not interfere with scientific research or the teaching of science in our schools.

50  As I have stated above in this essay, the K-12 general biology supplement Of Pandas and People contains some misleading information. It also makes some very simplistic comparisons that are inappropriate for an academic science course designed to prepare young minds for the future of science and technology. For example, if we see the words "John Loves Mary" written in the sand, we know that this message was written by an intelligent designer called Homo sapiens sapiens. Then why can't a message written in the DNA of our genes also be made by an intelligent designer? This is another example of an oversimplified comparison. We know from experience that people write messages in the sand. Probably everyone has done this at one time in their life. But we can only hypothesize about the origin of coded messages in DNA, or for that matter, the origin of DNA. We can say that DNA is so marvelous and complex that is must have come from an intelligent designer, but now we are basing our conclusion on faith, not science. That is why intelligent design does not belong in a science class. Although proponents of intelligent design are very careful not to specify who their "designer" is, the logical conclusion is that it must be God. We have freedom of religion in the United States guaranteed by the First Amendment of the Constitution. It is not wrong to believe that our God is the intelligent designer; however, explanations of the natural world based on faith just don't belong in a science class.

51  During the famous Dover School Board Trial of fall 2005, proponents of intelligent design argued that their "theory" was not based on biblical creationism. They even claimed that their recommended supplemental biology textbook Of Pandas and People (2nd. Edition, 2004) did not center around creationism. The latter testimony was repudiated by Dr. Barbara Forest after she discovered early drafts of the textbook with the words "creation" instead of intelligent design. In one draft (pp. 3-41), the word "creationists" was incompletely replaced by the words "intelligent design." It is clear that intelligent design is synonymous with creationism.

52  The Biophysical Society is an international society of scientists established to encourage development and dissemination of knowledge in biophysics. The following comes from their concluding paragraph regarding the teaching of alternatives to evolution in K-12 science classrooms (November 5, 2005): "Attempts to suppress or compromise the teaching of evolutionary science in the United States are misguided actions that will deprive our youth of a clear understanding of the scientific process, and of the scientific skills that they need to compete in a global economy: one that is increasingly driven by science and technology. Moreover, current efforts to disguise theology as science do a severe disservice to the scientific profession and to the people of the United States."

53  Since intelligent design is not science, it does not belong in the science curricula of the nation's primary and secondary schools. This is the position statement of the following prestigious scientific organizations: National Academy of Sciences, American Association for the Advancement of Science, National Science Teachers' Association, American Geophysical Union, American Chemical Society, American Association of Physics Teachers, and the American Astronomical Society. All of these organizations emphasize the importance of scientific methodology as well as articulating well-established scientific theories.

54  Some authors have used the extrapolation of Darwin's Origin of a Species by Means of Natural Selection to include the first macromolecules and living cells, although this has never been proven through rigorous scientific analysis. They have even speculated that macromolecules and living cells evolved purely by random chance. A functional protein may contain more than 500 amino acids arranged in a specific orderly sequence with a unique 3-dimensional structure. The probability for the 2-dimensional arrangement of 500 amino acids is astronomical. It is equivalent to 1 in 20⁵⁰⁰ or roughly 1 in 10⁶⁵⁰. Some models of the visible universe list 10⁸⁰ for the total number of subatomic particles. William A. Dembski, a staunch proponent of intelligent design has come up with his universal probability bound, a numerical value that gauges the likelihood that a given event could have occurred by chance in nature, or whether it occurred by intelligent design (i.e. by a natural or supernatural intelligence). Dembski's probability bound is a cutoff point between probability and a "creator." It is based on a very improbable number (1 in 10¹⁵⁰), derived from the inverse of the product of several astronomical numbers, including the number of subatomic particles in the universe. Whether this number is the cutoff point between random probability and a creator is impossible to prove. For an intelligent review of Dembski's mathematical explanation for intelligent design, please read "The Dream World of William Dembski's Creationism" by Mark Perakh in Skeptic Volume 11 (Number 4) 2005, pages 54-65.

55  Given the plausible conditions and energy forces of a primitive earth atmosphere, the origin of life was probably a lot more likely than simple random probability. Some of these "natural" conditions and forces may have included simple compounds in a "primordial soup," including water, methane, ammonia and hydrogen, shallow pools lined with clay particles bearing electrostatic charges, heat and electrical discharges (lightning), and a time window of countless million of years. Whether a supernatural force was also involved in this process is perhaps one of the most controversial topics ever discussed by educated people.

56  Standing on the rim of this enormous canyon and gazing out at the colorful strata representing over a billion years of geologic time, you realize the brief life span of a mortal human. Was this magnificent canyon created in its present form by God, or was it formed during millions of years of sedimentation, uplifting and erosion? If it was underwater during the worldwide biblical flood, how did all the animals become stratified into layers dating back to the Cambrian period over 500 million years ago? Were all these creatures treading water at the same time during the great flood, only to die and settle out in layers?

57  Fossil evidence indicates that numerous species of animals lived during different periods of time. As layers of sediments were deposited, animals from each time period were recorded in the strata as fossils. About 40-70 million years ago, the Grand Cayon region was uplifted into a high plateau during a tremendous mountain building era known as the Laramide Orogeny. This massive uplifting gave rise to the Rocky Mountains and the origin of the Colorado River drainage. During the past six million years, the Colorado River has cut through this high plateau region, as it winds its way to the low Colorado Desert and eventually to the Gulf of California. The river's steep gradient of 8 feet per mile (1.5 m per km) and high sediment load contributed to its cutting power. Rockfalls, landslides, flash floods from torrential rains, and ongoing erosion in tributary canyons, have worked in tandem with the Colorado River to widen the canyon and form the intricate cliff and slope pattern seen today.

58  There is overwhelming evidence from paleontology and geology that the Grand Canyon's strata and all of its ancient life evolved during the past 550 million years. To suggest that it was created in its present form, or that all of this occurred during the last 6,000 years as stated in the Bible, is based purely on faith. Some people with a much broader interpretation of the Bible believe their faith does not conflict with the objective scientific evidence.