Biological evolution

Skull comparison of Thylacinus cynocephalus and Canis lupus.

Biological evolution is the process through which the characteristics of organisms change over successive generations, by means of genetic variation and natural selection. It is most commonly defined as "changes in gene frequencies in populations." The result of the process may be minimal or substantial; it embraces everything from slight changes within a species, to the successive alterations that lead to the diversification of an organism into countless unique species.

Creation scientists accept the observable quantity of change taking place within living organisms - often called microevolution, but contest the assertion by Darwinists that this process has led to the existence of all life on Earth. Biological evolution should not be confused with the general theory of evolution, which also includes cosmological evolution. In addition, changes such as metamorphosis or embryonic development are not considered evolutionary. Biological evolution transcends the lifetime of a single individual and is best summarized as the changes that are inherited through genetic information from one generation to the next.

A frequent point of confusion is generated because many evolutionists use the term biological evolution to refer to either the process of change, or the theory of common descent of living organisms (see: Equivocation). Note the following definition from Talk.Origins.

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Biological evolution is a change in the genetic characteristics of a population over time. That this happens is a fact. Biological evolution also refers to the common descent of living organisms from shared ancestors.

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However since this aspect of theory of evolution is highly theoretical and unsupported by actual observations, it is better addressed on this site as part of the articles on the general theory of evolution or Darwinism. Creationists acknowledge the process of biological evolution, but insist that this assertion of Darwinism is a farce, contradicted by enormous amounts of scientific evidence.

Views

When interpreted through the theist and atheist worldviews, biological evolution has varying explanatory power. Darwinism holds that every characteristic of every organism arose through genetic variation and natural selection. In contrast, creationists believe that biological evolution can explain some characteristics, but that others bear the hallmarks of intelligent design. Creationists and evolutionists also strongly disagree on the origin of biological evolution: that is, how life came to have the ability to reproduce and vary over generations.

Creation

Main Article: Creation

Creation scientists credit major structural characteristics to God's creation, and variation within that structure to the designed process known as biological evolution. The process of biological evolution can only exist within organisms already able to reproduce, and each appears only able to evolve within the bounds of their original framework. For example, biological evolution can lead to a change in the size of a bird's beak or a change in a population's skin tone, add fur, and otherwise allow the organism to adapt and find its niche. It cannot explain major irreducibly complex biological processes like sexual reproduction or blood clotting. Nor can it account for predictions such as the evolution of fish to amphibian, or ape to human.

Creationists believe that life was created and intentionally given the capacity for biological evolution. Thus, the capacity to reproduce and vary is itself credited to God's creative act. God endowed life with the capacity for biological evolution so that life could thrive and spread over the earth: so that it could adapt to changing conditions. Creationists see genetic recombination as strong evidence for this: specifically, the fact that certain areas of the genome (such as those controlling body shape) vary a great deal, while others (such as those controlling the operation of cellular organelles like the mitochondria) vary little if at all, indicates that there is some mechanism guiding the process of variation itself, causing the genome to vary where variation is useful, and remain virtually unchanged where variation will most likely be harmful.

Darwinism

Main Article: Darwinism

When referring to biological evolution it is important to make a clear distinction between the process that induces change in a population and common descent as purported by Darwinism. Biological evolution itself is an obvious, observable, empirical fact that organisms vary genetically and morphologically through successive generations. On the other hand, Darwinism is the historical speculation that life originated naturalistically without any creative act (abiogenesis), that all life on Earth is related (common descent), and that all the complexity, adaptability, and artistry of life on Earth is due solely to random change and natural selection. Darwinism holds that life's capacity for biological evolution came about by chance and natural selection. The theory of evolution, which includes Darwinian views on biological evolution, also holds that chemicals, moving randomly reached a configuration that allowed them to reproduce, which ultimately led to the first cell.

Microevolution

Microevolution is a quantum of evolution that is supported by observations of living organisms. It describes the varieties that develop within a population, which are due to changes in gene frequency over time. The term microevolution typically refers to the small scale changes in organisms within the same species, which can lead to a subspecies or even new species. Such evolution is consistent with the creationist view and supports the diversification of the Biblical kinds following the flood of Noah.

The term microevolution however, asserts that over time, new genetic material is being manufactured, but only within the family or kind. An example would be Darwin's finches and their variety of beaks. Microevolution presumes a starting-point of an initial beak form while all other forms are a function of new genetic material. However, in a model where the finch's genome is pre-constructed as highly adaptive, the alleles are already present to support the wide variety in beaks. This allows finches to rapidly diversify into many different varieties in a short period of time while continuing to leverage allele frequencies to achieve it. Microevolution, which requires new genetic material, is a far slower mechanism. When discussing the subject, it is important to center on adaptation as the mechanism and that the adaptive capacity is pre-constructed. The genes actively adapt to the passive environment rather than the environment acting to elicit change in otherwise passive genes.

It is important to note that the variation observed in living organisms is limited. This has been exemplified by centuries of domestic breeding history. There are today many varieties of dogs, but they remain dogs. There are many variations of livestock such as horses or cows, but again they are simply varieties of distinct kinds. This diversification does not necessarily or inherently lead one to the concept that all living creatures came from a common ancestor. An atheistic philosophy was responsible for such a conclusion.

Microevolution is distinguished from macroevolution, which is a larger scale change that results in the formation of higher taxonomic groups. It should however, be noted that many creationists caution against using the term or terms when debating.

According to the University of California's Museum of Paleontology:

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"Microevolution is evolution on a small scale — within a single population. That means narrowing our focus to one branch of the tree of life. If you could zoom in on one branch of the tree of life scale — the insects, for example — you would see another phylogeny relating all the different insect lineages. If you continue to zoom in, selecting the branch representing beetles, you would see another phylogeny relating different beetle species. "

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Scientific American draws the following distinction:

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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.

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Macroevolution

Main Article: Macroevolution

Macroevolution is a purely theoretical process thought to produce relatively large (macro) evolutionary change within biological organisms. The term is used in contrast to minor (microevolution) changes, and is most commonly defined as "evolution above the species level". Macroevolution can not be observed directly, but is instead studied through the examination of fossils (paleontology) and the similarities and differences in the anatomy of organisms (comparative morphology)..

It is thought to provide the mechanism by which an original taxa (i.e. phylum or class) may change enough to result in newly descendant phyla or classes. The development of new taxonomic groups requires new types of structures (morphology) and functions.

According to the University of California's Museum of Paleontology:

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"Macroevolution is evolution on a grand scale — what we see when we look at the over-arching history of life: stability, change, lineages arising, and extinction." "Macroevolution generally refers to evolution above the species level. So instead of focusing on an individual beetle species, a macroevolutionary lens might require that we zoom out on the tree of life, to assess the diversity of the entire beetle clade and its position on the tree."

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The concept of macroevolution was introduced due to the absence of transitional forms between higher taxa (i.e. phyla, classes), which is in stark contrast to the expectations of Darwinian gradualism. It was therefore proposed as a mechanism responsible for large-scale patterns of evolution, which are distinct from the genetic and small-scale factors that contribute to gradual change within populations. These smaller scale changes are those defined as microevolution.

Processes

Biological evolution involves the following as explanatory mechanisms: Genetic variability, Speciation, and Natural selection.

Genetic Variability

Main Article: Genetic variability

Genetic recombination encompasses a number of mechanisms by which DNA is reshuffled in each generation, so that children are genetically distinct from the parents. It includes both the reorganization of genes that occurs in sexual reproduction, as well as the creation of new alleles. It is the primary source of genetic diversity and variation in gene pools.

The observable facts of genetic recombination are not in dispute between creationists and evolutionists. In fact, the principles of heredity and recombination were first discovered by Gregor Mendel, a creationist, a monk, and a scientist. Subsequent research has determined that recombination takes place even below the level of the gene, so that new alleles can be formed by the reshuffling of genetic material.

Evolutionists and creationists disagree, however, on the nature of this reshuffling. Evolutionists view it as random, accidental mutations. Creationists, on the other hand, believe that organisms were designed with the ability to reshuffle genetic material to introduce genetic diversity to a gene pool.

In support of their view, creationists point to the observable fact that genetic recombination does not occur at random. On the contrary, some sections of the genetic code vary and recombine a great deal, while other sections vary little if at all. Sections that vary a great deal include skin color, height, muscle mass, intelligence, etc. Sections that do not vary much, if at all, include those controlling metabolism, cellular structure, and similar fundamental, structural components. Creationists argue that if variation were random, then we would expect to see variation at an equal rate across the genome. They argue that the fact that recombination occurs in a non-random pattern indicates that there is some mechanism controlling the variation to allow it only in places that are advantageous to the genome, a possibility that supports the creationist hypothesis.

Speciation

Main Article: Speciation

Creationists would also agree with evolutionary biologists that the processes of genetic recombination and natural selection can result in the formation of new species. In fact, creationists believe that extremely rapid evolution occurred after the Flood to create the species that we see today from the smaller number of species that were on the ark.

Creationists find themselves at odds with evolutionists in regards to naturalistic abiogenesis and common descent. These aspects of the theory of evolution are simply unsupported by the scientific method, and largely the result of atheistic philosophy. As such, the belief that evolution alone is responsible for all organisms on earth is better classified as evolutionism.

Natural Selection

Main Article: Natural Selection

Traits are found to exist within a population in a variety of forms, and these differences will afford individuals a greater or lesser chance of success. If the trait is beneficial to the organism, then its genes will be passed to the next generation at a higher frequency, or vice versa if it is harmful. This is said to be the "natural selection" of a trait.

The fact that natural selection happens is not open for dispute. Organisms do adapt to their environment and the role of natural selection in this process is certain. However, evolutionists do not view genetic information nor the cellular mechanisms responsible for genetic diversity as being the result of intelligent design. Neodarwinism assumes that random mutations are responsible for this information or the variability from which nature selects.

Examples

There are many examples of adaptive change in living populations that has been used in support of the general theory of evolution or common descent, but none that have demonstrated evolution from one kind of organism to another. In addition, many examples have shown that such adaptation can occur very rapidly and often involves the loss of genetic information.

For example, the beak evolution of Galapagos Finches ("Darwin's Finches") helped Darwin postulate his theory of evolution through natural selection. However, recent research has determined that climate change can stimulate remarkable adaptive change incredibly fast - in just decades - a process which turns out to be surprisingly complex as noted by the following article in the journal Science.

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Evolution has proven predictable in the short term but unpredictable over the course of decades, they report. Climate change has been a powerful influence guiding the evolution of the finches--and its effects turn out to be surprisingly complex. Darwin's Avian Muses Continue to Evolve Science April 26 2002: 633

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Although the variations in beak size that Darwin witness demonstrates microevolution, it does not offer the support needed for macroevolution or common descent to be true. Furthermore, the changes observed in finches occur over short spans of time that is more supportive of creationist predictions of rapid diversification since the flood, rather than evolution through mutations over millions of years.

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The problem is that Darwin ... taught that this adaptation could explain the general theory of evolution (GTE). But the finch beak variation is merely the result of selection of existing genetic information, while the GTE requires new information.

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Jonathan Sarfati offers other examples in his book Refuting Evolution 2

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There are other related examples, e.g., one way that the Staphylococcus bacteria becomes resistant to penicillin is via a mutation that disables a control gene for production of penicillinase, an enzyme that destroys penicillin. When it has this mutation, the bacterium over-produces this enzyme, which means it is resistant to huge amounts of penicillin. But in the wild, this mutant bacterium is less fit, because it squanders resources by producing unnecessary penicillinase. Another example is a cattle breed called the Belgian Blue. This is very valuable to beef farmers because it has 20–30% more muscle than average cattle, and its meat is lower in fat and very tender. Normally, muscle growth is regulated by a number of proteins, such as myostatin. However, Belgian Blues have a mutation that deactivates the myostatin gene, so the muscles grow uncontrolled and become very large. This mutation has a cost, in reduced fertility. A different mutation of the same gene is also responsible for the very muscular Piedmontese cattle. Genetic engineers have bred muscular mice by the same principle.

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Rapid evolutionary rates

If the world is as old as is commonly claimed, we should see animals today evolving at a rate consistent with this, over thousands and millions of years. That is why it is shocking for the scientific community that the accumulating evidence shows instead that Microevolution occurs over decades, rather than thousands and millions of years. David Skelly of Yale University has observed that the evolutionary rates are far faster than those presumed by evolutionary theory:

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Ecology is being transformed by the recognition that ecological and evolutionary timescales are not easily differentiated. A 1999 review of evolutionary rates by Andrew Hendry and Mike Kinnison (The pace of modern life: measuring rates of contemporary microevolution. Evolution 53:1637-1653) provided the striking conclusion that rates of contemporary evolution are much faster than generally appreciated... Our work reveals that a number of traits including critical thermal maximum, embryonic development rate, and thermal preference behavior all show variation consistent with local adaptation that occurs on the scale of decades and tens of meters. These findings offer a startlingly different picture of interactions between organisms and their environment prompting us to rethink, in larger sense, how we should conceive of ecological assemblages.

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Australia's 'Toxic Toad'

In one of the most widely publicized cases of unexpected rapid Microevolution, Australian Cane Toads defied predictions based on evolutionary theory by experts about how they would react after being introduced to Australia. Within decades they evolved longer legs and heat tolerance, running amok and causing havoc for the wildlife; and instituting a national catastrophe for the continent.

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The evolutionary processes spawned by the cane toad invasion have occurred in a span of just 70 years. This adds to evidence from the past two decades that populations can adapt quickly when selection pressure is strong. 'We're taught evolution occurs over these very, very long time frames. But in systems like these, it's incredibly fast,' Shine, the study co-author, said.

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'All of a sudden in the last 10 years it changes,' said Skelly. 'They're moving into areas where the physical environment is not like anything in their native range.' That implies that the cane toads have evolved more tolerance for the hotter climates they are now encountering. This is on top of the discovery last year that the toads at the forefront of the invasion had evolved longer legs than those in the interior of their range. The ability of animals to evolve so quickly needs to be factored into invasions, or the dangers of invasive species will likely be underestimated, argue Skelly and his colleagues Mark Urban, Ben Phillips and Richard Shine in an article in the March 28 issue of the Proceedings of the Royal Society-B.

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Human Evolution

According to the assumptions of evolutionary theory, if evolution always went at the rate that we see today, there should be 160 times more differences between humans and apes. So rather than assume 'the present is the key to the past', scientists then decided that evolutionary rates today have accelerated for some reason.

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If humans had always evolved at this rate, the difference between modern humans and chimps should be 160 times greater than it really is. 'We realized we must be in a transient [phase], that evolution hasn't been going this fast for long in our species,' Harpending said. 'And so we wondered why.'

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'I was raised with the belief that modern humans showed up 40,000 to 50,000 years ago and haven't changed,' explained Henry C. Harpending, an anthropologist at the University of Utah. 'The opposite seems to be true.'... If evolution had been proceeding steadily at the current rate since humans and chimps separated 6 million years ago there should be 160 times more differences than the researchers found. That indicates that human evolution had been slower in the distant past, Harpending explained.

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Italian Wall Lizards

In 1971, scientists introduced 5 pairs of Italian Wall Lizards to a small island off the coast of Croatia. However, the Croatian War of Independence prevented the scientists from returning to the island for more than 30 years. When the war ended, tourism finally began again in 2004, allowing them to return. The researchers were unsure if the lizards would still be alive. Instead, they found the island swarming with lizards, which genetic testing showed to be descendants of their original 5. The new lizards had wiped out native lizard populations by evolving cecal valves, muscles between the large and small intestines, with which to digest native vegetation, an expanded gut structure, as well as a harder bite.

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Italian wall lizards introduced to a tiny island off the coast of Croatia are evolving in ways that would normally take millions of years to play out, new research shows. In just a few decades the 5-inch-long (13-centimeter-long) lizards have developed a completely new gut structure, larger heads, and a harder bite, researchers say... Such physical transformation in just 30 lizard generations takes evolution to a whole new level, Irschick said. It would be akin to humans evolving and growing a new appendix in several hundred years, he said. 'That's unparalleled. What's most important is how fast this is,' he said.

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Plant Evolution

Contrary to theoretical predictions based on evolutionary theory, genomes for the Angiosperm Silene (a flowering plant) evolved far more rapidly than was expected, as reported in the January 2012 issue of PLoS Biology. Researchers are now trying to find an explanation for why such rapid Microevolution is occurring, and a new model that will avoid such surprises in the future.

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Contrary to theoretical predictions, these genomes have experienced a massive proliferation of noncoding content... The evolution of mutation rate, genome size, and chromosome structure can therefore be extremely rapid and interrelated in ways not predicted by current evolutionary theories... We discuss the implications of the unprecedented mitochondrial genome diversity found within Silene and possible alternative explanations for the rapid genome evolution in this genus.

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Rodent Evolution

A 2009 study observed that rodents evolve at "unprecedented rates" given climate change and population growth, and that rapid evolutionary change in rodents has been occurring for over a century. The article also notes research on rapid Microevolution has previously been "infrequently documented", but that despite this, more and more evidence is cropping up for it.

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Our results indicate that over the last 100+ years, rapid morphological change in rodents has occurred quite frequently, and that these changes have taken place on the mainland as well as on islands. Our results also suggest that these changes may be driven, at least in part, by human population growth and climate change.

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Types

• Convergent evolution is the independent appearance of the same trait in different lineages. Evolutionists assert that such traits are due to homologous DNA sequences that have arisen independently in unrelated organisms by random mutations and similar selective pressures. In contrasts, creationists and intelligent design theorists attribute such homology to the creator's repeated use of the same design features in different organisms. According to Paul Nelson and Jonathan Wells:

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An intelligent cause may reuse or redeploy the same module in different systems, without there necessarily being any material or physical connection between those systems. Even more simply, intelligent causes can generate identical patterns independently.

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• Co-evolution - Unique species that are ancestrally unrelated yet share an intimate history due to, for example, symbiosis. For example, the co-evolution of flowering plants and pollinators such as bees.

• Adaptive radiation - Extreme adaptations by species that arises due to the need to fill empty ecological niches. This type of evolution is usually found within ecosystems developed on isolated islands.

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