I once spent an afternoon on the northwestern shore of the Sea of Galilee, atop the mount where Jesus is believed to have preached his most famous sermon. It was an infernally hot day, and the sanctuary where I At some time, the myth tells us, heaven and earth were united, and then they were separated.
The separation of Sky and Earth made possible the appearance of man. The poem introduces us to elements that we see repeated again and again in ancient myths: First, creation was not from nothing, which you never find in ancient myth, but from something that was already there. What was it? We see these two elements used in the pyramid texts, which come from Egypt around the year B. They refer to the creation of the world in order to guarantee the vigor of the glorified king, buried in an artificial primeval hill.
On this hill, Atum, the creator god took his stand:. O Atum-Kheper, you who were on high on the primeval hill! You did arise as the ben -bird of the ben -stone in the ben -house in Heliopolis. You did spit out what was Shu, you did sputter out what was Tefnut. So when scientists talk about the theory of evolution—or the atomic theory or the theory of relativity, for that matter—they are not expressing reservations about its truth.
In addition to the theory of evolution, meaning the idea of descent with modification, one may also speak of the fact of evolution. Although no one observed those transformations, the indirect evidence is clear, unambiguous and compelling. All sciences frequently rely on indirect evidence. Physicists cannot see subatomic particles directly, for instance, so they verify their existence by watching for telltale tracks that the particles leave in cloud chambers. The absence of direct observation does not make physicists' conclusions less certain.
Natural selection is based on circular reasoning: the fittest are those who survive, and those who survive are deemed fittest. That is, rather than labeling species as more or less fit, one can describe how many offspring they are likely to leave under given circumstances. Drop a fast-breeding pair of small-beaked finches and a slower-breeding pair of large-beaked finches onto an island full of food seeds.
Within a few generations the fast breeders may control more of the food resources. Yet if large beaks more easily crush seeds, the advantage may tip to the slow breeders.
In pioneering studies of finches on the Galpagos Islands, Peter Grant and Rosemary Grant of Princeton University observed these kinds of population shifts in the wild. The key is that adaptive fitness can be defined without reference to survival: large beaks are better adapted for crushing seeds, irrespective of whether that trait has survival value under the circumstances.
Evolution is unscientific because it is not testable or falsifiable. It makes claims about events that were not observed and can never be re-created. This blanket dismissal of evolution ignores important distinctions that divide the field into at least two broad areas: microevolution and macroevolution. Microevolution looks at changes within species over time—changes that may be preludes to speciation, the origin of new species.
Macroevolution studies how taxonomic groups above the level of species change. Its evidence draws frequently from the fossil record and DNA comparisons to reconstruct how various organisms may be related. These days even most creationists acknowledge that microevolution has been upheld by tests in the laboratory as in studies of cells, plants and fruit flies and in the field as in the Grants' studies of evolving beak shapes among Galpagos finches.
Natural selection and other mechanisms—such as chromosomal changes, symbiosis and hybridization—can drive profound changes in populations over time. The historical nature of macroevolutionary study involves inference from fossils and DNA rather than direct observation.
Yet in the historical sciences which include astronomy, geology and archaeology, as well as evolutionary biology , hypotheses can still be tested by checking whether they accord with physical evidence and whether they lead to verifiable predictions about future discoveries.
For instance, evolution implies that between the earliest known ancestors of humans roughly five million years old and the appearance of anatomically modern humans about , years ago , one should find a succession of hominin creatures with features progressively less apelike and more modern, which is indeed what the fossil record shows.
But one should not—and does not—find modern human fossils embedded in strata from the Jurassic period 65 million years ago. Evolutionary biology routinely makes predictions far more refined and precise than this, and researchers test them constantly. Evolution could be disproved in other ways, too. If we could document the spontaneous generation of just one complex life-form from inanimate matter, then at least a few creatures seen in the fossil record might have originated this way.
If superintelligent aliens appeared and claimed credit for creating life on Earth or even particular species , the purely evolutionary explanation would be cast in doubt. But no one has yet produced such evidence. New species evolve by diverging away from established ones and acquire sufficient differences to remain forever distinct. It should be noted that the idea of falsifiability as the defining characteristic of science originated with philosopher Karl Popper in the s.
More recent elaborations on his thinking have expanded the narrowest interpretation of his principle precisely because it would eliminate too many branches of clearly scientific endeavor.
No evidence suggests that evolution is losing adherents. Pick up any issue of a peer-reviewed biological journal, and you will find articles that support and extend evolutionary studies or that embrace evolution as a fundamental concept.
Conversely, serious scientific publications disputing evolution are all but nonexistent. In the mids George W. Gilchrist, then at the University of Washington, surveyed thousands of journals in the primary literature, seeking articles on intelligent design or creation science.
Among those hundreds of thousands of scientific reports, he found none. Krauss, now at Arizona State University, were similarly fruitless. Creationists retort that a closed-minded scientific community rejects their evidence. Yet according to the editors of Nature , Science and other leading journals, few antievolution manuscripts are even submitted. Some antievolution authors have published papers in serious journals.
Those papers, however, rarely attack evolution directly or advance creationist arguments; at best, they identify certain evolutionary problems as unsolved and difficult which no one disputes.
In short, creationists are not giving the scientific world good reason to take them seriously. The disagreements among even evolutionary biologists show how little solid science supports evolution. Evolutionary biologists passionately debate diverse topics: how speciation happens, the rates of evolutionary change, the ancestral relationships of birds and dinosaurs, whether Neandertals were a species apart from modern humans, and much more.
These disputes are like those found in all other branches of science. Acceptance of evolution as a factual occurrence and a guiding principle is nonetheless universal in biology. Unfortunately, dishonest creationists have shown a willingness to take scientists' comments out of context to exaggerate and distort the disagreements.
Anyone acquainted with the works of paleontologist Stephen Jay Gould of Harvard University knows that in addition to co-authoring the punctuated-equilibrium model, Gould was one of the most eloquent defenders and articulators of evolution. Punctuated equilibrium explains patterns in the fossil record by suggesting that most evolutionary changes occur within geologically brief intervals—which may nonetheless amount to hundreds of generations.
Yet creationists delight in dissecting out phrases from Gould's voluminous prose to make him sound as though he had doubted evolution, and they present punctuated equilibrium as though it allows new species to materialize overnight or birds to be born from reptile eggs. Fossil record shows a succession of hominins, with features becoming progressively less apelike and more modern.
When confronted with a quotation from a scientific authority that seems to question evolution, insist on seeing the statement in context. Almost invariably, the attack on evolution will prove illusory.
This surprisingly common argument reflects several levels of ignorance about evolution. The first mistake is that evolution does not teach that humans descended from monkeys; it states that both have a common ancestor. The parent species may survive indefinitely thereafter, or it may become extinct. The origin of life remains very much a mystery, but biochemists have learned about how primitive nucleic acids, amino acids and other building blocks of life could have formed and organized themselves into self-replicating, self-sustaining units, laying the foundation for cellular biochemistry.
Astrochemical analyses hint that quantities of these compounds might have originated in space and fallen to Earth in comets, a scenario that may solve the problem of how those constituents arose under the conditions that prevailed when our planet was young. Creationists sometimes try to invalidate all of evolution by pointing to science's current inability to explain the origin of life.
But even if life on Earth turned out to have a nonevolutionary origin for instance, if aliens introduced the first cells billions of years ago , evolution since then would be robustly confirmed by countless microevolutionary and macroevolutionary studies. Many scientists and theologians have written about how one can accept both faith and the valid- ity of biological evolution. Many past and current scientists who have made major contributions to our understanding of the world have been devoutly religious.
At the same time, many religious people accept the reality of evo- lution, and many religious denominations have issued emphatic statements reflecting this acceptance. To be sure, disagreements do exist. The range of beliefs about science and about religion is very broad.
Regrettably, those who occupy the extremes of this range often have set the tone of public discussions. Evolution is science, however, and only science should be taught and learned in science classes. Acceptance of evolution is not the same as a religious belief.
To be accepted, scientific knowledge has to withstand the scrutiny of testing, retesting, and experimentation. Evolution is accepted within the scientific community because the concept has withstood extensive testing by many thousands of scientists for more than a century. Many religious beliefs do not rely on evidence gathered from the natural world.
On the contrary, an important component of religious belief is faith, which implies acceptance of a truth regardless of the presence of empirical evidence for or against that truth. Scientists cannot accept scientific conclu- sions on faith alone because all such conclusions must be subject to testing against observations. How can random biological changes lead to more adapted organisms? Contrary to a widespread public impression, biological evolution is not ran- dom, even though the biological changes that provide the raw material for evolution are not directed toward predetermined, specific goals.
But some mutations give organisms traits that enhance their ability to survive and reproduce, while other mutations reduce the reproductive fitness of an organism.
Others may be unable to adapt to a changing environment and will become extinct. As with all active areas of science, there remain questions about evolution. There are always new questions to ask, new situations to consider, and new ways to study known phenomena. But evolution itself has been so thor- oughly tested that biologists are no longer examining whether evolution has occurred and is continuing to occur.
Similarly, biologists no longer debate many of the mechanisms responsible for evolution. As with any other field of science, scientists continue to study the mechanisms of how the process of evo- lution operates. As new technologies make possible previously unimaginable observations and allow for new kinds of experiments, scientists continue to 50 Science, Evolution, and Creationism.
But the existence of such questions neither reduces nor undermines the fact that evolution has occurred and continues to occur. Nor do such questions diminish the strength of evolutionary science. Indeed, the strength of a theory rests in part on providing scientists with the basis to explain observed phenomena and to predict what they are likely to find when exploring new phenomena and observations.
In this regard, evolution has been and continues to be one of the most productive theories known to modern science. Even scientific theories that are firmly established continue to be tested and modified by scientists as new information and new technologies become available.
As Press pointed out, both illustrations reflect the efforts of humans to understand the natural world. The answer lies at the very heart of the nature of this system of study we call science. Beginning in the early s, a network of satellites has allowed anyone with a hand-held receiver to know his or her position on Earth to within a few feet. Yet the technology originated with a purely scientific objective--the desire to build extremely accurate clocks to test Einstein's theory of relativity.
The tremendous success of science in explaining natural phenomena and fostering technological innovation arises from its focus on explanations that can be inferred from confirmable data. Scientists seek to relate one natural phenomenon to another and to recognize the causes and effects of phenomena. In this way, they have developed explanations for the changing of the seasons, the movements of the sun and stars, the structure of matter, the shaping of mountains and valleys, the changes in the positions of continents over time, the history of life on Earth, and many other natural occurrences.
By the same means, scientists have also deciphered which substances in our environment are harmful to humans and which are not, developed cures for diseases, and generated the knowledge needed to produce innumerable labor-saving devices.
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