DOES EVOLUTION DISPROVE THE BIBLE? By James A. Murray Does the scientific account of the evolution of life on Earth conflict with religious descriptions of creation, and if so, how? The common questions that puzzle all people are: "How did life come to be on Earth?" "Why am I here and what is my relationship to other living things?" "Why is there such a great diversity of living things?" Life on earth is inseparably linked to evolution, and nearly all scientists, especially biologists, accept evolution as fact. Evolution is the idea that living things have changed over time. For instance, dinosaurs existed 80 million years ago; today they do not. Extinction is one way life on Earth can change. Fossil evidence indicates that 99% of all species that ever lived are extinct. Biologists also agree that natural selection exists and that it contributes to evolution. Natural selection is differential success in reproduction and can result in evolution if: (a) individuals with-in a population differ from one another in any characteristic, (b) these differences are inherited from parents through genes, and (c) populations produce more offspring than the environment can support. Individuals whose inherited genetic characteristics fit them best to their environment are likely to leave more offspring than those that do not fit as well. For example, one species of moth has both white forms and black forms. For the most part, white forms beget white young and black forms beget black young. The color difference between them is heritable, that is, based on their genes. When industrial air pollution turned whole forests black with soot, the moths that survived to reproduce were those few that were black [1]. The black form had a selective advantage over the white form because the black form could hide from predators on the blackened trees more easily than the white form could. Predators reduced the formerly predominant white form to only 1% of the population. This is an example of natural selection in which a natural force, in this case bird predators of moths, selects for black-colored moths by selecting against (i.e., preventing their reproduction by eating them) white-colored moths. Can evolution by natural selection cause a species to split into two species or even drive the evolution of millions of species from one species that existed a few billion years ago? Most biologists today contend that evolution by natural selection is the major creative force that accounts for the diversity of life. The controversy between evolutionists and creationists exists probably because both sides make many of the same predictions about the observable features of life. Both predict that living organisms should fit well into their environments. Both predict that organisms should function well. Both predict that the forms of an organism and its parts should follow from their function. But evolutionary theory makes two critical and testable predictions that differentiate it from creationist ideas. First, evolutionary theory predicts the existence of fossils of long extinct organisms, and the lack of ancient fossils of the more recently evolved species because living things were not all alive at the same time. Second, evolutionary theory predicts that organisms will not be designed perfectly. Rather, the form of an organism will be shaped principally by two forces, the functions the organism must carry out, and the form of its ancestors. It is this requirement that an organism's form be partly the result of the form of its ancestors that precludes perfect design in a species that has evolved. If a species were created by God to serve a purpose, then presumably it would be perfectly adapted to its environment and the same design would not be used for animals with different purposes. How can we test the predictions of evolutionary theory or disprove the hypothesis that all organisms on Earth evolved from common ancestors? Let's look at the two critical predictions made by evolutionary theory, the fossil evidence and the design constraints imposed by common ancestry. Evolutionary theory predicts that the common ancestors of all organisms lived long ago and the only surviving offspring are those species that exist today. There are fossilized bones from giant reptile-like dinosaurs that existed 200 to 65 million years ago. Of course, such terrible animals do not exist today; they are extinct. How do we know these fossils are as old as we think they are? One of the most reliable measures is that from radioactive dating [2]. Radioactive substances become less radioactive as they emit their radiation, and each radioactive element has a fixed and characteristic rate of decay. By measuring the present radiation level in a specimen, and knowing how radioactive it was when first incorporated into the fossil, one can infer the length of time that passed since it was fossilized. Fossils are found in sedimentary rock that formed from dirt and mud accumulating on the bottom of lakes and oceans. The oldest sedimentary rocks formed just when the Earth was cool enough not to melt them, about 3.5 billion years ago, and they have fossils of bacteria in them [3]. Life existed soon after the Earth was cool enough to not destroy the molecules that make up life. Independent methods of dating fossils and the sediments that contain them corroborate the radioactive dating. One such method is to measure the rate of sedimentation over short periods of time and infer how long it would take to produce sediments of the depths found on Earth today. The other major prediction of evolutionary biology is that the forms of organisms are in part constrained by their ancestry. If a creator started from scratch in making each organism, the creator would have no such constraint, and would be able to design each organism optimally, without extraneous parts. Alternatively, if some organisms descended from others, one would expect that they would retain some primitive characteristics even if the characteristics were no longer functional. There is an abundance of fossil evidence that shows that fish have existed roughly 30% longer than have reptiles and mammals. For 100 million years the only vertebrates were fish [4]. Fish have no hip bones. They don't walk, so this is not surprising. Vertebrates that walk do have hip bones; again, not surprising. What is surprising is that some vertebrates that do not walk but whose ancestors walked, like whales and some snakes, do have hip bones. These are functionless organs, vestiges from ancestors long dead. Would a creator build creatures with functionless parts? Why would those extraneous parts look like the functional parts found in their ancestors? The biologists' answer is that whales and snakes have descended from a common ancestor of terrestrial vertebrates that walked, and have retained the vestigial hip bone found in many members of that lineage. Human embryos, developing in the womb, have five functionless gill slits which eventually close up. Why would humans, and all other vertebrates, develop gills slits that they were not going to use? Why are early human and shark embryos nearly indistinguishable when they are destined to live extremely different lives? Biologists believe it is because of an old genetic program, found in all fish and descendants of fish, that has not yet been lost despite its uselessness in non-fish. We humans appear to have descended from fish-like ancestors. Modern day humans and apes appear to have descended from a common ancestor. Fossils of ape-like humans and human-like apes have been found dating to 7 million years ago [4]. Before then, only hybrid-like forms are found. Our respective lineages split 5-10 million years ago when humans took to the plains and apes stayed in the forest. Yet our genes are remarkably similar - 97.5% identical. Species that we are more distantly related to, like mice, share only 70% of our genetic material. The genetic similarity follows our close ancestry. On the basis of examples like these and thousands more like them, biologists contend that all living things descended from common ancestors by a process called evolution. One of the criticisms of evolution is that the evolution of life from lifelessness defies the Second Law of Thermodynamics. This law states that anything or group of things will become more disordered as long as no energy is added to them. The Earth has certainly become more ordered since it cooled off 4 billion years ago. The reason this increasing order does not defy the Second Law of Thermodynamics is that the sun constantly showers the Earth with energy, and has ever since Earth was born. Our sun's energy powers evolution. Another criticism is that the probability of a living being spontaneously coalescing out of its constituent elements is absurdly low, and therefore a creator must have designed life. In other words, a watch implies a watchmaker. The probability of even the simplest form of life, a bacterium, spontaneously forming from its constituent elements is infinitesimal. But the probability of a bacterium evolving from simpler precursors may be very high. Both bacterial and human genetic materials are made of a remarkable chemical called nucleic acid, which consists of long chains of smaller molecules called nucleotides. Molecules of nucleic acid can make copies of themselves. So if one molecule of nucleic acid spontaneously arose on the early earth, it could have replicated itself into many more copies. Some of these copies may have had errors in them, i.e., changes in the nucleotide sequence in the chain. Would the original or the new version replicate faster? If the new version made copies faster, it would soon overpopulate the original version. The new version would have been naturally selected for in the evolutionary scheme. This process of copying and miscopying of nucleic acid sequences is believed to have led to the evolution of all life on Earth. It is an automatic process that occurs without design or a designer. Biologists do not claim that all life arose spontaneously from chemicals, but rather that life evolved from chemicals that arose spontaneously. Nucleic acid had to arise spontaneously for life to have begun on Earth without outside influence. There is much evidence that nucleic acids and other biochemicals could have spontaneously formed on the early Earth [5] or arrived on meteorites and comets. Creationists claim that if evolution were true we would see a continuum of forms of organisms rather than the distinct species we find today; if all organisms evolved from ancestors by gradual change, then intermediate forms should exist. Actually, many plants and microbes do not consist of distinct species but can hybridize readily. But many animals are distinct species that can not interbreed. The intermediate forms from which these separate species evolved are presumed to be extinct. The common ancestor of humans and chimpanzees is extinct, and we have found fossilized pieces of this common ancestor's skeleton. But fossils are rare and hard to find, and sometimes no fossilized intermediate forms have been found. This does not imply that the intermediate form did not exist. A lobe-finned fish species thought to link fish to amphibians was believed to be extinct for 70 million years until a live specimen was found in the Indian Ocean. Fossils of this fish were missing in 70 million years worth of sediments, yet the animal existed. This is a vivid example of how incomplete the fossil record is. The evolutionary explanation of life's presence and diversity differs from religious accounts of creation and obviously challenges much of the material in the Bible. If one interprets the account given in Genesis of the Old Testament literally, then evolution does conflict with it. Genesis (1:11-16) states that God created grass and trees before the sun, moon, and stars. All of physics and biology assert that the sun, and moon, and most of the stars are older than any plant species. Genesis 1 states that God created the entire universe in six days. Physicists maintain that the universe is at least 10 billion years old and more likely 14-20 billion years old. Using Biblical genealogies (Genesis 5, 10-11; Matt 1) and the assertion that no man would live more than 120 years (Genesis 6:3), one can show that the Earth described in the Bible could not be older than 8000 years [6]. Most anthropologists would assert that humans have been on Earth for at least 2 million years. The Earth is about 4.5 billion years old based on radioactive dating and independent measures. Scientists can safely say that the Biblical account of creation is not literally true. The examples given here only scratch the surface of a mountain of accumulating evidence that supports evolution. The references below should give the skeptical reader a more detailed account of what evolutionary biology tells us about life on Earth and the origins of humanity. ---------------- References: 1. Kettlewell, B. (1973) The Evolution of Melanism. Clarendon Press, Oxford. 2. Brush, S. G. (1982) Finding the age of the Earth by physics or by faith? Journal of Geological Education vol. 30: pp. 34-58. 3. Knoll A. H., Barghoorn E. S. (1977) Archean microfossils showing cell division from the Swaziland system of South Africa. Science vol. 198: pp. 396-398; Schopf, J.W. (1993) Microfossils of the early Archean apex chert: New evidence of the antiquity of life. Science vol. 260: pp. 640-646. 4. Campbell, N. A. (1987) Biology. Benjamin/Cummings Publishing, Menlo Park, CA. 5. Schopf, J. W. (ed.) (1983) Earth's Earliest BiosphereC Its Origin and Evolution. Princeton University Press, Princeton, NJ. 6. Renckens, H. (1964) Israel's Concept of a Beginning: The Theory of Genesis 1-3. Herder and Herder, New York Further reading: Futuyma, D. J. (1983) Science on Trial. Pantheon Books, New York. [Answers common criticisms by creationists and has a list of articles on the evolution/creation debate.] Deamer, D.W., Fleischaker, G.L. (eds.) (1994) Origins of Life: The Central Concepts. Jones and Bartlett, Boston. de Duve, C. (1995) Vital Dust: Life as a Cosmic Imperative. Basic Books, New York. Robertson, M.P., Miller, S.L. (1995) Prebiotic synthesis of 5-substituted uracils: A bridge between the RNA world and the DNA-protein world. Science, vol. 268: 702-705. ---------------- James A. Murray is a Postdoctoral Fellow at UCSD in the Department of Biology, and a member of the San Diego Association for Rational Inquiry. He can be reached in care of SDARI or by email: jamurray@ucsd.edu.