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Natural Selection is one of the mechanisms which drives evolution. It is popularly characterized as "survival of the fittest," though that is not always the most accurate description. It is the tendency for life forms which are best suited to their environments to have a better chance to reproduce than those that are not. For example, in a cold environment, an animal with lots of fur is more likely to reproduce than a bald animal, since the bald animals will die more quickly.
[ References: Wikipedia: Natural Selection ]
Evolution is often criticized by opponents as being "just a theory." This argument is especially common in America, where the word "theory" usually means an unproven idea. However, in science a theory is the highest degree of certainty. Gravity is "just a theory." The Earth orbiting the Sun is "just a theory." By definition, a scientific theory is a hypothesis which has withstood rigorous testing and is well-supported by the facts. There is overwhelming evidence for biological evolution, just as there is overwhelming evidence for gravity.
[ References: Talk Origins: Evolution is a Fact and a Theory ]
This is an issue which often confuses the general public, as the two words, theory and law, have very different common meanings. But in science, their meanings are very similar. A theory is an explanation which is backed by "a considerable body of evidence," while a law is a set of regularities expressed in a "mathematical statement." This is why Newton's Laws of Motion are referred to as laws and not theories. They are expressed with simple equations (like f = ma for his 2nd Law of Motion). Evolution, and most of Biology, cannot be expressed in a concise mathematical equation, so it is referred to as a theory. A scientific law is not "better" or "more accurate" than a scientific theory. A law explains what will happen under certain circumstances, while a theory explains how it happens.
[ References: Kennesaw State University: Scientific Laws and Theories ]
Yes. Evolution has been observed both in the laboratory (diseases adapting to become resistant to drugs) and in nature (new species of flowers, mice, insects, etc. developing).
While it is true that new traits can appear through the accumulation of small random genetic mutations, it is the non-random process of Natural Selection that determines which traits to keep and which to discard. For example, a random mutation may cause a brown squirrel to be born white. But if the squirrel lives on a brown tree, its color will quickly alert predators to its existence. The white squirrel will not live long enough to reproduce and pass on the trait. In this environment, nature selects for brown squirrels, not white. If the process were random, then the white squirrel would survive just as well as the brown.
While it is true that many mutations can cause problems for an organism, sometimes lethal, not all mutations are harmful. Most mutations are caused by single-point errors in the copying of a strand of DNA. For example, a strand of ATAGC may change to ATATC. This can have three major effects: a deleterious effect, a positive effect, or no effect at all. Deleterious effects, those which threaten the survival of the organism, will not accumulate, because they will kill the organism before it has a chance to reproduce. Conversely, mutations which cause no effect or a positive effect will accumulate in a population's genome. This is how Natural Selection works. It "selects" for positive changes in the genome, because only the positive changes will accumulate.
Certain mutations can add new, large pieces of DNA at a time. See this question on Gene Duplication for more information.
[ References: TalkOrigins: Mutations adding information ]
This is accomplished through a process called Gene Duplication, which is believed to play a major role in Evolution. Because of a mistake during meiosis, an organism may end up with two copies of the same gene. After this happens, the usual mechanisms of point mutation and natural selection can evolve one of the copies into coding for something completely new, while retaining the original gene. To test how quickly gene duplication can occur, an experiment was performed on yeast in 1998. After only 450 generations, it was discovered that the "hexose transport" genes had duplicated several times.
This claim is based on the calculations of all of the millions of molecules in a single cell forming by chance. No scientist believes this is how life formed. Instead, most theories of "abiogenesis" begin with simple self-replicating molecules which could have formed naturally. It is believed that such a self-replicating molecule formed the earliest versions of DNA. After many thousands of years of adaptations, all governed by the non-random process of Natural Selection, did the first microbe finally develop.
For a more detailed explanation of the math involved, please see the article on this site titled The Probability of Life.
[ References: Probability of Abiogenisis Calculations (Talk Origins) ]
While there is no direct fossil evidence for the evolution of DNA (because of its size and fragility), scientists have theorized on its origins based on verified laboratory evidence. One theory goes like this: DNA began as a simple self-replicating peptide, possibly containing no more than 32 amino acids, which formed naturally (and somewhat easily) in the early oceans of Earth.
Once self-replication had been achieved, the forces of Natural Selection took over. For example, those molecules which were protected from the elements survived longer and reproduced more. So, any molecules which found themselves with a lipid bubble (which also forms naturally) would have a better chance of reproducing. After many incremental steps, the lipid bubbles eventually became cell membranes, and the molecules DNA.
For more information on the probability of life forming this way, please see this article.
As of the time of this writing, no, scientists have never created cellular life in a laboratory from scratch. The technology simply does not yet exist to manipulate molecules with the precision required to create all of the inner workings of a cell, built one atom at a time.
However, many of the important building blocks of life have indeed been created in a laboratory, including amino acids, self-replicating RNA molecules, and self-sealing and self-replicating lipid bubbles (ie, cell membranes) which are profound steps toward the goal of one day creating fully-synthetic life.
The "fossil record" refers to the placement of fossils throughout the surface layers of the Earth. Older fossils are buried more deeply than younger ones. Scientists use the placement of fossils as a guide for determining when life forms existed, and how they evolved. For example, we know that flowering plants evolved from non-flowering plants because, in the fossil record, we see flower fossils becoming more and more primitive the deeper we go, until they disappear all together. There are no flower fossils below a certain depth. This shows us that flowering plants evolved from non-flowering plants, then began to diversify themselves. This kind of progression is found throughout the fossil record.
[ References: Wikipedia: Fossil Record ]
Transitional fossils bridge gaps between two species. Due to the difficulties in creating fossils in the first place, and the fact that speciation sometimes occurs very quickly in small groups, transitional fossils can be rare in the fossil record. However, even given these circumstances, there are still thousands of transitional fossils known to science, including those illustrating the evolution of modern fish, the transition of fish to amphibians, amphibians to reptiles, reptiles to birds, reptiles to mammals, and the evolution of human beings (as well as many other species).
Please see this video for great examples of transitional fossils: http://www.evolutionfaq.com/vi
Also, see this Wikipedia page detailing just a partial list of transitional fossil examples: http://en.wikipedia.org/wiki/L
Firstly, man did not evolve from modern apes. Man and modern apes share a common ancestor, which is extinct. However, the question comes from a flawed understanding of how evolution works. Evolution is not a straight line, where entire populations change into new species all at the same time. Often times, a small group breaks away from a population and begins to evolve independently of the source group. The source group does not need to go extinct, and is generally unaffected by the development of the smaller group. This is called "Allopatric Speciation," and it is just one of many ways that new species can evolve. There is nothing in evolutionary theory which states a source population must go extinct in order for new species to evolve.
The concept of a "missing link" between humans and apes arose in the 19th century, when the fossil record was largely incomplete. Large gaps separated species, casting doubt on the theory of evolution. But in the last 130 years, a plethora of fossils have been discovered, greatly narrowing the gaps between species. The Australopithecus afarensis fossil known as "Lucy" is considered to be a key fossil bridging the gap between humans and primitive hominids.
[ References: Wikipedia: Astralopithecus afarensis ]
Of course. Many faiths accept evolution as the explanation for the current level of biodiversity, usually stipulating that a creator initially designed the Universe, or guided the processes of evolution. In fact, in 1996, Pope John Paul II reaffirmed the Catholic Church's position that evolution does not conflict with Christianity. Evolution does not contradict the overall philosophy of the Bible, Torah, Koran, or any religious text.
Darwin was very proud of his scientific discoveries, and it is highly unlikely he would have recanted them. There is no supporting evidence for this story, and Darwin's daughter, who was at her father's deathbed, refutes it. But even if it were true, it would not matter. Biological evolution has been experimentally proven many times over. The worth of a theory is measured by how well it is supported by the facts, not by who believes it.
[ References: Darwin's Deathbed Conversion - a Legend? (Mitchell, 2009) ]
No, this is a bit of an "old wive's tale." Our smallest toe (or 'pinkie toe' as some call it) is here to stay. This is because organisms don't just lose traits or appendages simply because they aren't useful anymore. There would need to be a threat to our survival or reproduction, directly caused by us having our smallest toe. In that scenario, individuals born with smaller pinkie toes would have an advantage over those with longer ones. Over many generations, this would cause pinkie toes to get smaller and smaller, until gone.
This is how whales lost their small hind legs, for example. A more streamlined whale swims faster, and so evades predators and catches food faster. This drove their legs to get smaller and smaller until they virtually vanished (though in skeletons you can still see their pelvises). However, there are no pressures like this involving our pinkie toes.
No. According to Newsweek magazine, 99.85% of American earth and life scientists accept biological evolution as a fact. Gallup polls also show that 95% of all scientists accept evolution, though it should be noted that this figure includes scientists who study in unrelated fields, like Computer Science, Engineering, etc. The vast majority of scientists accept evolution as fact.
Radiocarbon dating is just one of many "radiometric" dating techniques. While contamination in the laboratory might happen on rare occasions, radiometric dating remains a trusted and reliable method of determining the age of a sample. The technique relies on the constant rate of decay of certain radioactive elements in the sample. For example, rubidium-strontium dating relies on the decay of rubidium-87 to strontium-87. Rubidium-87 has a half-life of 50 million years (the amount of time for half its mass to decay into strontium). Using this figure, scientists measure the amount of rubidium and strontium in a sample to determine its age.
[ References: Wikipedia: Radiometric Dating ]
The second law states that "In a closed system (one in which energy cannot enter), Entropy will not decrease." Since Entropy often refers to disorder, this law is often taken to mean that order cannot arise from disorder. How then would life, which is highly ordered, form naturally? The answer, simply, is that life is not a closed system. Energy is constantly being added to the Earth from the Sun, which fuels the plants, which in turn fuel other life. This is how plants, for example, can have more energy than the seeds they originally sprouted from. But life is not the only example of order from disorder. Snowflakes, crystals, lightning, and sand dunes are all examples of non-living matter organizing into complex structures.
[ References: TalkOrigins: Five Major Misconceptions about Evolution ]
Intelligent Design (ID) is the hypothesis that a higher intelligence (ex: a god, space aliens, time travellers from the future, etc.) guided the course of evolution. Most often, Intelligent Design refers to a god, typically the Christian/Jewish/Muslim god, YHWH or Allah. In other words, God from the Bible.
ID differs from traditional religions in that proponents recognize that biological evolution is responsible for the development and diversity of life on Earth. It is similar to traditional religions in that it typically posits a supernatural explanation for what guided the evolution of certain species (including humans). In this way, ID is similar to the 4th century BC belief put forward by Plato and Aristotle of a "prime mover," that is, a being which set the natural world in motion.
This has been a hotly debated question in the media, classrooms, and many churches. According to authors like Michael Behe, there are certain structures in nature which he terms "irreducibly complex," which, he asserts, could not have evolved naturally. He gives bacterial flagellum and the eye, among others, as examples. If true, these might be evidence for Intelligent Design.
However, the vast majority of the scientific community regards Intelligent Design as psuedoscience or "junk science." The structures that Behe and others give as examples have proven evolutionary histories. For an example, watch The Evolution of the Eye video on this site. Recently at the famous Dover trial, the court held that "Professor Behe's claim for irreducible complexity has been refuted in peer-reviewed research papers and has been rejected by the scientific community at large."
To date, there has never been any evidence, agreed upon by the scientific community, to be proof of Intelligent Design.
It is often argued that the eye is so complex that it could not have evolved naturally. The idea being that an eye with only "half" the parts in place would not work, therefor evolution would have never favored it and the more complex human eye we have would never have evolved.
However, the evolution of the eye has been studied extensively, and its history is more-or-less well established. First, there were light-sensitive cells which merely indicated which way was the Sun. A slight indentation makes a sense of direction possible. Mucus in the pit focuses the light. If the mucus hardens, you have a proper lens, and so on.
In fact, every stage of the eye's development is still around on Earth today. A snail's eye is less than "half" a human eye, yet it serves the snail well enough to help its survival.
Please watch this video which beautifully describes the evolution of the eye for a more visual example.
[ References: Wikipedia - Evolution of the Eye ]
This is a statement often asserted by proponents of Intelligent Design, but it is simply not true. The argument goes that since the flagellum (the tail-like structure many bacteria have which helps them "swim") is a very complex machine, it could not have evolved naturally. This is because if you remove any of the proteins that make up the flagellum's motor, it can no longer function.
However, as this video beautifully demonstrates, the flagellum does function with fewer proteins, just not as a flagellum. Every part of the flagellum is made of proteins already in the cell, performing other functions. This is one of the most interesting aspects of Evolution: that adaptations can change roles, or combine with other adaptations to perform new roles.
No. A religion is a set of beliefs based on the supernatural, which by definition is untestable and impossible to disprove (or "unfalsifiable").&nb
While scientists may place faith in a scientific theory, their faith is based on past evidence. For example, all scientists have faith that the Law of Thermodynamics will hold true during an experiment because there is overwhelming past evidence to support this belief. This is completely different than placing faith in a religious belief, which has no supporting evidence at all.
This argument comes from a paper published in 1979 by astronomer John Eddy. After studying observations from 1836 through the 20th century, he found the sun had contracted 2 arc seconds. He had found proof of what atronomers had suspected and know for a fact today: that the sun's diameter oscillates in an 80 year cycle. It does not constantly shrink.
Within the sun, and every star, there are 2 opposing forces: the intense gravity of the star, trying to crush it, and the intense heat of nuclear fusion, trying to blow it apart. As the gravitational field causes the surface to shrink ever so slightly, it builds incredible pressure inside the star, which speeds up the fusion reactions (think of a pressure cooker). The increased fusion then pushes the surface back out again, and the cycle starts over. Because the sun is truly gigantic, about 1 million times the size of Earth, this cycle plays out on what we would consider a slow scale: every 80 years.
[ References: The Legend of the Shrinking Sun (Till) ]