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Every year on Darwin's birthday, I like to repost/update my essay explaining evolution and the evidence for it. Darwin's theory of evolution has been one of the most robust theories in science. With some modifications, it is still the basis of our understanding of most of biology. Every Feb 12th (Darwin's Birthday) I post an article or series of articles discussing evolution and the evidence for Darwin's theory. Below is probably all you ever need to know about evolution as a robust, well-supported scientific theory.

Darwin's theory grew out of an era when a considerable amount of careful observation from around the world was beginning to be formulated into careful scientific ideas. Not all ideas from this era were equally scientific, nor equally valid. Charles Darwin's theory was formulated based on a huge amount of observation both personally made by Darwin and made by correspondents he wrote to from all over the world. It took many years for Darwin to put his ideas into words and his book, Origin of Species, spends a great deal of time addressing criticisms of the theory of Evolution. When Darwin formulated his theory, the Mendelian rules of genetics were unknown, and DNA wasn't even conceived of. So, in essence, the mechanisms and rules that govern evolution were unknown. Darwin defined the patterns of how living things changed and competed, and it was only later that those mechanisms were discovered, giving the statistical and molecular context for Darwin's theory. Those later discoveries have only strengthened Darwin's theory, never contradicting his ideas.

The most fundamental basis for the theory of evolution is the very simple and very evident observation that individuals within a species vary from one another. This may seem so obvious that it seems silly to state it, but it really is the foundation of Darwin's theory and he spends an entire chapter of his book demonstrating variability within species in nature. We now know that this variation is due to genetic differences, differences in the DNA sequence, among individuals. Darwin did not know this. He simply observed that in every species he had any information on, individuals showed clear differences in appearance, in abilities, in behavior and in internal structures. Simple differences like human skin color or our differences in eyesight are examples of this. What is important about individual variation is that such variations can make an individual better or worse able to survive within a given environment and produce children. Since producing children is what contributes to the next generation, differences in an organism's chances of surviving and reproducing can determine whether or not that individual organism contributes to the next generation.

Throughout his book, Darwin compares what happens in nature to the simpler situation of human breeding of domestic animals. Humans select for larger fruit size, higher milk or wool production, less aggressive bulls, etc. and that selection is based on individual differences among individual animals or plants. Over time, our selection of certain traits can make that trait predominant in the animals we have domesticated. As Darwin summarizes it:

"No one supposes that all the individuals of the same species are cast in the very same mould. These individual differences are highly important for us, as they afford materials for natural selection to accumulate, in the same manner as man can accumulate in any given direction individual differences in his domesticated productions."

In other words, in the same way that humans select for specific traits within the diversity of a population of domesticated plants or animals, natural selection will do the same thing in nature. This natural selection is little different than what humans do when they select particular traits to breed for in our show dogs, our cattle, our wheat plants, etc. The only difference is natural selection is not directed towards a specific goal the way human breeding of domesticated plants and animals is.

What is natural selection? Clearly a plant or animal that can withstand cold better than another, say one rabbit has a thicker coat of fur than another, it is more likely to survive a cold winter or in colder climates than a plant or animal less able to withstand cold. The thicker furred rabbit would be better adapted to the colder conditions, so would be more likely to survive and reproduce. But the thinner furred rabbit may do better in warmer conditions. That is natural selection. Individual traits that favor survival in a particular environment will improve the chances that the genes (to use modern terms) of that individual get passed on to the next generation. Animals that are poorly adapted die before they can produce many offspring, and hence their genes do not remain in the population. A trait that is bad for an individual's survival is unlikely to survive for many generations in a population. That is natural selection: the constraints the environment puts on populations of organisms, favoring the survival and reproduction of some individuals over other individuals.

Darwin came up with this after considering Malthus' theory of population growth. Malthus postulated that populations tend to expand exponentially (geometrically, meaning 2 become 4 become 16 become 256, etc.) while food production expands linearly (2 becomes 4, becomes 8, become 16, etc.). So, Malthus states that over time, populations will expand beyond their ability to find food and hence undergo periods of severe decline due to disease and starvation.

Darwin thought about this and realized that this process of rapid population growth and crash means that there is a selective pressure on a population that favors individuals that can survive the cycles of boom and bust. He recognized that several environmental factors would affect this including competition with other species and within a species. Hence, the basic Malthusian population dynamics would create a situation whereby each individual would be in constant competition with all other individuals of all other species in a given environment for survival. Or, as Darwin put it:

"If during the long course of ages and under varying conditions of life, organic beings vary at all in the several parts of their organization, and I think his cannot be disputed; if there be, owing to the high geometrical powers of increase [reproduction] of each species, at some age, season, or year, a severe struggle for life, and this certainly cannot be disputed; then, considering the infinite complexity of existence, causing an infinite diversity in structure, constitution, and habits, to be advantageous to them, I think it would be a most extraordinary fact if no variation ever had occurred useful to each being's own welfare, in the same way as so many variations have occurred useful to man. But if variations useful to any organic being do occur, assuredly individuals thus characterized will have the best chance of being preserved in the struggle for life; and from the strong principle of inheritance they will tend to produce offspring similarly characterized. This principle of preservation, I have called, for the sake of brevity, Natural Selection."

Variation occurs, competition occurs, so variation that improves an individual's chances of surviving the competition is selected for and passed on to offspring.

There is another layer of selection that tends to get ignored when Darwin's theories are considered, and yet Darwin considered it just as important as natural selection. That layer is sexual selection. Natural selection is the selective pressure for certain traits over others due to the fierce competition for survival among all organisms in a given environment. Sexual selection is simply the tendency for certain traits to be favored by other members of a species in a mate. These often are NOT traits that are beneficial in natural selection and can sometimes seem bizarre. Selection by peahens for peacocks with particularly large and dazzling tail feathers is actually selecting for a tail structure that makes the peacock MORE vulnerable to being killed by predators. And yet, the fact that peahens favor it is still a selective pressure for a large and dazzling tail. Many such examples of sexual selection can be seen in nature, as well as in any pick up bar in any city on earth. If a trait, for whatever reason, is favored by the opposite sex, then individuals with that trait will be more likely to reproduce and so pass on the genes for that trait. It is the COMBINATION of natural and sexual selection, acting on individuals of a species that vary from one another, that drive evolution.

As a population changes, it may come to differ from other populations of the same species. This is a well-known phenomenon whereby multiple varieties can exist of the same species. Our domestic dog, cat, cattle, etc. breeds are examples of this. Such varieties can easily be crossed back together to lose their distinct characteristics, but the tendency to have those characteristics will remain. For example, crossing two breeds of dogs will give you a mutt, but that mutt will still have some of the genes of the pure breeds and it's offspring will show similarities to the pure breeds. Varieties occur in nature, often when different populations of a species are separated by a physical barrier: a river, lake, mountain, etc. Darwin spends a great deal of time outlining the observations concerning varieties and how most of those same observations could be applied to species as well. He showed how over time the differences between isolated varieties would increase, producing sub-species and, eventually, new species. This is the final part of Darwin's theory. Variation within a species, acted on by natural and sexual selection, lead to geographical divergences within a species into varieties, then sub-species and finally species. He discusses how the differences between varieties and species can be controversial, leading one scientist to declare two populations mere varieties of one species, and another scientist to declare them two separate species. He suggests that varieties and species are merely opposite ends of one process. I will discuss this in more detail below when I deal with more modern evidence supporting Darwin's theory.

Darwin argues that the way different species are distributed around the world and how they differ from each other is easily explainable by his theory of evolution, where different species branch off of a common progenitor species, as opposed to the then commonly believed theory that each species was separately and independently created. He spends many chapters simply showing how the observed distribution and structures of living things on earth today is more consistent with his theory than with the theory of independent creation of each and every species. For example:

"We have seen that the members of the same class [of organisms], independently of their habits of life, resemble each other in the general plan of their organization...What can be more curious than that the hand of a man, formed for grasping, that of a mole for digging, the leg of the horse, the paddle of the porpoise, and the wing of the bat, should all be constructed on the same pattern, and should include the same bones, in the same relative positions?...

"Nothing can be more hopeless than to attempt to explain this similarity of pattern in members of the same class, by utility or by the doctrine of final causes...On the ordinary view of the independent creation of each being, we can only say that so it is;--that its has so pleased the Creator to construct each animal and plant.

The explanation is manifest on the theory of natural selection of successive slight modifications,--each modification bring profitable in some way to the modified form...In changes of this nature there will be little or no tendency to modify the original pattern or to transpose parts."

In other words, the similarity of the structure and pattern of the bones of human hands, horse legs, whale fins and bat wings doesn't make sense in terms of similarity of function, because these limbs are used for very different purposes. It seems rather sloppy of a Creator to use this same pattern for all these limb types if independent creation is believed. Independent creation would logically have each limb separately designed for its particular purpose and there is no reason for the identical pattern of bones, including cases where some bones are no longer useful but still remain as vestigial elements in the limb. However, evolution would say that they all have the same pattern because they all were formed from the limbs of a common ancestor by gradual changes over millions of years by natural selection. It is the most logical explanation for all such similarities in structure across classifications of organisms. Now that we understand genes and DNA, we find an even better fit between reality and Darwin's theory.

We now know that the origin of variation is mutation in the DNA. DNA is a molecule with, in essence, a 4-letter alphabet and "words" made up of 3 letters that tell the cell what amino acid goes where in a given protein. DNA also tells the cell under what conditions a protein should be turned on or off. Together, this is what determines what each individual organism looks like, can do and even, to a large degree, how it behaves.

Mutations occur from two sources. Both are, in essence, random. One source is the fact that the molecular machinery for replicating our DNA sometimes makes errors. Most of these errors are edited out. But sometimes the editing machinery fails and a real mutation occurs. The second source is from the environment: many chemicals (natural and artificial) as well as UV and higher energy radiation cause mutations in our DNA. Again, often these mutations are repaired, but sometimes they slip through.

Mutations in DNA can be silent (have no effect), can alter the structure of a protein, or can alter the way a protein is turned on and off. When a change is made, it often impairs the function of the protein, but occasionally simply alters it in a neutral way or actually improves it. These mutations that lead to changes in the way a protein works or is regulated are the source of variations among individuals. Again, it is by and large a random process (actions of scientists like myself aside).

Natural selection gives the direction to evolution. Changes in a species due only to random mutations with no real selection is called genetic drift, and it can happen in isolated situations. But in general, species change due to natural and sexual selection, directing the changes towards an improved survival or reproductive potential. Changes that produce new varieties and new sub-species are observed all the time in domesticated animals, in nature and in the laboratory. It is the change that leads to the origin of NEW species that is harder to see, though I will show below that it is indeed observable.

The lack of precision that existed during Darwin's day in determining varieties from sub-species to species has been improved thanks to DNA. We can compare the DNA sequences of two groups and tell exactly how closely related they are. This comparison, on a smaller scale, is what we do when we do modern paternity tests or DNA fingerprinting in criminal cases. On a larger scale, this kind of analysis has shown that the wooly mammoth is very closely related to the modern Asian elephant. In essence, the Asian elephant and mammoth are sister species and both are close cousins to the African elephant. It is also the technique that has shown that Eurasians have a small amount of Neanderthal DNA in them, representing a part of the genetic difference between Eurasians and Africans. Only way THAT could have happened is if Neanderthals and modern humans "had morning coffee" (to use the Japanese idiom for it) on occasion. The same kind of analysis revealed not only that there was a previously unknown species of humans in Asia, the Denisovans, but that traces of their DNA can be found in modern Melanesians, indicating another example of ancient human subspecies having their euphemistic "morning coffee."

The same DNA analysis that can give us DNA fingerprinting can, with greater care, give us relationships among species including an estimate of how long it has been since those two species diverged. These kinds of relationships on the level of DNA are far harder to explain if each species was created independently than if modern species evolved from common ancestor species the way Darwin hypothesized.

So in the more than 100 years since Darwin published Origin of Species, scientific discoveries that Darwin could never have imagined have done nothing but bolster his theory of evolution. It is a theory that was tenuous, though carefully thought out and reasoned, at the time. Further observations at that time all fit well with Darwin's theory. Mendel's laws of genetics fit very well with Darwin's theory and could almost have been devised by Darwin himself since he had done some very similar experiments, but just hadn't done them as extensively as Mendel. Finally, the discovery and understanding of DNA and the entire field of molecular biology, something that Darwin could never have even imagined, fit perfectly into the theory of evolution and in many ways explain aspects of evolution that seemed mysterious to Darwin himself.

Now I wish to discuss some of the objections that have been made to Darwin's theory and show how more than 100 years of research have done nothing but bolster or minorly modify Darwin's theory.

Ever since Charles Darwin first published Origin of Species, many who see his theory as somehow detracting from religion have tried to tear it down. They have pretty much failed from the start and the more we have learned of biology, the more evolution has been supported, if occasionally modified. Interestingly, most objections to Darwin's original theory were recognized and brought up by Darwin himself in Origin of Species. Far from avoiding or denying potential problems, Darwin approached them head on, giving his hypotheses as to how the problems would be solved over time. In general, his hypotheses have proven quite correct.

There are three particular objections that are often brought up to try and discredit evolution. First there is the problem of the gradual evolution of complex organs, such as the eye. How can random variation acted on by natural selection produce an organ as intricate and complex as the eye? Second there is the problem of intermediate species. If evolution is a slow and gradual process, why do we never see the intermediate species, the "missing links" either alive or in the fossil record? These two problems can be called the Problems of Missing Intermediates and can be solved by, in essence, pointing out that a.) intermediates will be rare and rapidly replaced by improved versions, and b.) in reality, intermediates CAN be seen in both instances. I will address these momentarily.

The third problem is, to some degree, more philosophical than scientific. Some argue that it is nothing but a theory of "chance" whereby random events produce wonderful things like eyes and wings. Much like an infinite number of monkeys on typewriters banging out Shakespeare's plays, this sounds very unsatisfying and even impossible. Put in somewhat scientific terms one could say that it violates the Second Law of Thermodynamics that dictates that, in essence, order cannot arise out of disorder without substantial input of energy. Chance cannot bring about order.

This objection is completely based on a false assumption: that evolution involves chance alone. To quote Richard Dawkins from his introduction to the 2003 Everyman's Library edition of Darwin's Origin of Species and Voyage of the Beagle:

The objection to Darwinism that it is a theory of "chance" is one of the most popular and most foolish of all. Mutation is indeed random, although only in the sense that it is not directed towards improvement. Natural selection is quintessentially the opposite of random. Any fool can see that random chance cannot put together living complexity. That is precisely why Darwinism is necessary. It is a preposterous irony that the statistical improbability of living organization is regularly advanced as though it counted against Darwinism, rather than in favor of it.

In other words, although mutation, the basis for variation, is indeed random to a large degree, that is only one part of Darwin's theory. The part that gives evolution its direction, if you want, is selection, both natural and sexual. There is no mere chance to evolution. It is directed by the pressures of the environment in which an organism lives. That is the very essence of Darwin's theory! Those who argue that it is a theory of mere chance have misunderstood the theory.

Now I want to address the first two objections I mentioned. How can something as complex as the eye be formed by small evolutionary changes and where are the intermediate forms of organs like the eye? And, why don't we see many intermediate species, either alive or in the fossil record, showing us the many gradations that take us from varieties within a species to separate species?

I will first address some things that apply to both. First off, the fossil record is not a complete record of evolution. Only a tiny fraction of all living organisms have become fossilized. Eons of the past in vast parts of the world have never survived in the fossil record. Conditions have to be just right for fossils to form. Even once formed, they can be destroyed by erosion and weathering. Finally, for us to ever see fossils they have to be exposed in just the right way at just the right time. Metaphorically, we are looking at a gigantic encyclopedia where most volumes are missing, the volumes we do have are missing pages, and the surviving pages are smudged. We cannot expect to have a complete fossil record wherein we can see every intermediate form through out evolution. Darwin himself went into this in great, almost excruciating, detail.

Another thing that Darwin himself points out about these objections is that imperfect intermediates are likely to be seen only in a small, isolated population for a short period of time. It is the MOST successful forms (either of organs or entire organisms) that compete the best and hence replace earlier, less successful intermediate forms. Intermediates IN GENERAL will be relatively rare and present for a short period of time on a geological scale compared with the more successful complete forms. So we are far more likely to only see the most successful forms of organs and organisms most of the time.  As Darwin himself puts it:

When we see any structure highly perfected for any particular habit, as the wings of a bird for flight, we should bear in mind that animals displaying early transitional grades of the structure will seldom continue to exist to the present day, for they will have been supplanted by the very process of perfection through natural selection.

In some ways these points eliminate the problems of the missing intermediates. The intermediates will be very rare and the fossil record, by its very nature, will be incomplete. But that is unsatisfying. One wants to say, "Yeah, but why don't we see ANY intermediates?" Even if they are rare and short lived, why aren't any alive TODAY?

The answer is that some ARE alive today and we DO see them. These objections are not only refutable logically as above, but they plain aren't true! Intermediate organs were mentioned by Darwin himself, and intermediate species were observed even in the period immediately after Darwin published and more have been discovered since then.

Taking the question of the evolution of a complex structure like the eye, Darwin points out that in Arthropods (or Articulata as they were called in Darwin's time) such intermediate, imperfect eyes DO exist in living organisms. Again, from Darwin himself (Darwin):

In the Articulata we can commence a series with an optic nerve merely coated with pigment, and without any other mechanism; and from this low stage, numerous gradations of structure, branching off in two fundamentally different lines [two different kinds of complex Arthropod eyes], can be shown to exist, until we reach a moderately high stage of perfection. In certain crustaceans, for instance, there is a double cornea, the inner one divided into facets, within each of which there is a lens-shaped swelling. In other crustaceans the transparent cones which are coated by pigment, and which properly act only by excluding lateral pencils of light, are convex at their upper ends and must act by convergence; and at the lower ends there seems to be an imperfect vitreous substance.

In other words, you CAN see various stages of the evolution of the eye in living animals. From a simple pigmented optic nerve, through various simple structures, up to the full compound eye of the fly, all are seen within the same broad category of animals.

One of the most complex aspects of living organisms is our cellular organization. Our cells are amazingly complex things, and their complexity has been used to claim that cells must have been designed by a creator. However, in 2009 evidence for intermediates leading up to cells was discovered: (from Science Daily)

Molecular Evidence Supports Key Tenet Of Darwin's Evolution Theory

"Our cells, and the cells of all organisms, are composed of molecular machines. These machines are built of component parts, each of which contributes a partial function or structural element to the machine. How such sophisticated, multi-component machines could evolve has been somewhat mysterious, and highly controversial." Professor Lithgow said.

A non-Darwinian explanation, from believers of Intelligent Design, proposed these complex machines to be "irreducibly complex". In other words they are so neatly complex and complete that they couldn't have evolved but rather must have been designed by an intelligent entity.

"Our research shows that these machines although complete and complex, were a result of evolution. Simple 'core' machines were established in the first eukaryotes by drawing on pre-existing proteins that had previously provided distinct, simplistic functions," Professor Lithgow said.

As a model system, the research focused on one specific molecular machine, the TIM complex, which transports proteins into mitochondria. Mitochondria are a compartment of human cells that serve as the energy-producing 'powerhouses'. At a very early stage in evolution, mitochondria were derived from bacteria that lived within the first eukaryotic cells.

"Our cells literally are chimeras of a "host" cell and these intracellular bacteria. Yet bacteria don't have TIM complexes – to understand where the TIM complex came from we simply applied scientific reasoning and looked at a modern-day bacterium akin to the organism that gave rise to mitochondria." Professor Lithgow said.

The group looked at the bacterium Caulobacter crescentus and found bacterial proteins related to the components of the mitochondrial TIM complex. They then showed that these bacterial proteins are not found as part of protein transport machines.

"François Jacob described evolution as a tinkerer, cobbling together proteins of one function to yield more complex machines capable of new functions." Professor Lithgow said.

"Our work describes a perfect example of Jacob's proposition, and shows that Darwin's theory of evolution beautifully explains how molecular machines came to be."

To discuss intermediates between full speciation, I have to go to other sources than Darwin himself. As early as 1863, Henry Walter Bates observed speciation in action. From Janet Browne's biography of Charles Darwin:

Bates gave an eyewitness account of the origin of species in nature. Two Amazonian butterflies, the black-and-crimson-spotted Heliconius melpomene and the Heliconius thelixope, if taken separately, were perfectly distinct species. Bates discovered four or five transitional forms living in particular geographical areas in between the two, each connected by a chain of gradations. The intermediate forms were not hybrids. They were geographical races, each on their way to becoming a separate species.

Other examples have been observed. One of the most striking and yet mundane are sea gulls. Gulls are an example of a phenomenon called a "ring species" where each neighboring population in a range of an organism can interbreed and represent mere varieties, but the opposite ends of the range have populations that cannot interbreed and are, by all definitions, separate species. From Carl Zimmer's companion book to the 2001 PBS series, Evolution:

In the North Sea, for instance, there is a species of bird known as the herring gull. It has a grey mantle and pink legs. If you move west through its range, you come across more herring gulls...which look essentially the same as the ones in the North Sea, except for a few minor differences in their coloring. But by the time you reach Canada, the differences become stark, and in Siberia, the gulls have a dark grey mantle and legs that are less pink than yellow. Yet despite these differences, they are still scientifically classified as the herring gull (although their common name is the vega gull). Keep moving through Asia and into Europe, and the gulls continue to get darker and more yellow-legged...all the way to the North Sea where your journey began. Here these gulls, known as the lesser black-backed gulls, live alongside the gray-mantled, pink-legged herring gulls.

Because the two groups of birds look so different and do not mate, they are treated as two separate species. Yet lesser black-backed gulls and herring gulls live at two ends of a continuous ring, inside of which all the birds can mate with their immediate neighbors. A ring species is exactly what you'd expect given the way mutations arise and spread.

Nothing could prove Darwin's hypothesis better than this! Here is speciation IN ACTION with two separate species side by side and a continuous series of gradations that can be followed that takes you from one to the other. Every step of the way is right there for us to see. Ring species like the gull are the most definitive proof of Darwin's theory you can get.

Theories are never "PROVEN" in a definitive sense. They are DISproven if contrary evidence is found. Sometimes a simple change in the theory can be made to accommodate the contrary evidence, preserving the basic theory in a modified form. Other times evidence so contrary is discovered that the entire theory has to be thrown out. If each new piece of evidence is in agreement with the theory, then that theory has support. Evolution has never been disproven. It has frequently been supported by more and more data. Arguably, some new data, such as mass extinctions from comet impacts, has required minor modifications of Darwin's theory, such as "punctuated equilibrium." But no major alterations to the basic design of "variation, selection, speciation" has been required. These foundations of Darwin's theory have ONLY been supported by the extraordinary advances in molecular biology (DNA and protein structure as the bases of variation), ecology (a better understanding of how natural selection and sexual selection work) and the discovery of more fossils and of phenomena like "ring species." The HUGE amount of new discoveries has only strengthened the more than 100-year old theory Darwin came up with. That is an astonishing robustness that has been matched by hardly any other theories in history. Newtonian physics can boast a longer period of dominance, from the 17th to 20th centuries when Einstein had to come up with some modifications. But not much else can boast as great a success as Darwinian evolution.

And 2005 brought even more support for Darwin's theory. From the December 23rd issue of the journal Science:

BREAKTHROUGH OF THE YEAR:
Evolution in Action
Elizabeth Culotta and Elizabeth Pennisi

Amid this outpouring of results, 2005 stands out as a banner year for uncovering the intricacies of how evolution actually proceeds. Concrete genome data allowed researchers to start pinning down the molecular modifications that drive evolutionary change in organisms from viruses to primates. Painstaking field observations shed new light on how populations diverge to form new species--the mystery of mysteries that baffled Darwin himself. Ironically, also this year some segments of American society fought to dilute the teaching of even the basic facts of evolution. With all this in mind, Science has decided to put Darwin in the spotlight by saluting several dramatic discoveries, each of which reveals the laws of evolution in action...

Probing how species split

2005 was also a standout year for researchers studying the emergence of new species, or speciation. A new species can form when populations of an existing species begin to adapt in different ways and eventually stop interbreeding. It's easy to see how that can happen when populations wind up on opposite sides of oceans or mountain ranges, for example. But sometimes a single, contiguous population splits into two. Evolutionary theory predicts that this splitting begins when some individuals in a population stop mating with others, but empirical evidence has been scanty. This year field biologists recorded compelling examples of that process, some of which featured surprisingly rapid evolution in organisms' shape and behavior.

For example, birds called European blackcaps sharing breeding grounds in southern Germany and Austria are going their own ways--literally and figuratively. Sightings over the decades have shown that ever more of these warblers migrate to northerly grounds in the winter rather than heading south. Isotopic data revealed that northerly migrants reach the common breeding ground earlier and mate with one another before southerly migrants arrive. This difference in timing may one day drive the two populations to become two species.

Two races of European corn borers sharing the same field may also be splitting up. The caterpillars have come to prefer different plants as they grow--one sticks to corn, and the other eats hops and mugwort--and they emit different pheromones, ensuring that they attract only their own kind.

Biologists have also predicted that these kinds of behavioral traits may keep incipient species separate even when geographically isolated populations somehow wind up back in the same place. Again, examples have been few. But this year, researchers found that simple differences in male wing color, plus rapid changes in the numbers of chromosomes, were enough to maintain separate identities in reunited species of butterflies, and that Hawaiian crickets needed only unique songs to stay separate. In each case, the number of species observed today suggests that these traits have also led to rapid speciation, at a rate previously seen only in African cichlids

This is just a sampling of the massive progress that has been made in one year alone, all completely in agreement or modifying in only minor ways Darwin's theory. For a more recent round up of supporting evidence for Darwin's theory, check out 12 Elegant Examples of Evolution from Wired magazine.

Ladies and gentleman, I think we have to recognize that Charles Darwin's theory of evolution is one of the most brilliant and most insightful scientific theories in the history of our species and it is WAY past time for it to be considered controversial. New studies are bound to modify his theory from time to time, but Darwin's theory is something we should cherish as a deep understanding of how life works.

The theory of evolution has itself evolved since Darwin's time. Darwin was convinced that evolution happened only on very long time scales in very slow increments. He believed the evolution of new species as well as the extinction of species would be almost imperceptible events, needing immense time spans. What he didn't know was that evolution can get boosts, not of mutation rates, necessarily, but in the nature of competition, when mass extinctions occur due to meteor or comet impacts, supervolcanoes, or rapid climate change. Such occurrences can lead to extinctions within a very short period of time...within months or years, rather than millions of years. When that happens, the survivors face a greatly reduced population as well as a greatly altered environment, leading to rapid evolution of new species. This is called punctuated equilibrium and is a modern modification of Darwinian evolution. Some people find punctuated equilibrium hard to swallow, but we DO know that mass extinctions occur. We see it in the fossil record and we find the impact craters that correspond in time to some of those mass extinctions. Punctuated equilibrium fits these observations better than any other theory to date.

Bibliography:

Browne, Janet; The Power of Place: Charles Darwin, the Origin and After, Knopf, 2002.

Darwin, Charles; Origin of Species and Voyage of the Beagle, Everyman's Library 2003 edition.

Zimmer, Carl; Evolution: the Triumph of an Idea, companion to the PBS series, Harper Collins, 2001.

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Originally posted to mole333 on Sat Feb 12, 2011 at 07:18 AM PST.

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Comment Preferences

  •  Thank you (5+ / 0-)

    Great explanation.  Now here's my question.  

    Just about contemporaneous with Darwin, if I recall, Gregor Mendel was doing his experiments with sweet pea flowers that showed dominant and recessive traits.

    Has someone done a good piece on the linkage between these two discoveries?  Because I'd like to hotlist it somewhere.

    •  Independent (7+ / 0-)

      Gregor Mendel worked pretty much in isolation. He did present his work at a couple of meetings but only published a small part of it, so he basic work on genetic laws he did wasn't really recognized until others independently replicated his work, then saw that he had done it first. Darwin and Mendel were, as far as I know, completely unaware of eachother's work.

      As an aside, Mendel is thought to have been a bit of a, shall we say, suspiciously lucky scientist. Not only did he choose traits that would segregate a certain way (unlinked traits, to use later genetic terms) but also the statistics that have been done on his data suggest he may well have thrown out data that didn't fit his hypothesis. Of course science wasn't as rigorous back then and his laws are definitely correct for unlinked traits, but he was probably selective about what data he used.

      FREEDOM ISN'T FREE: That's why we pay taxes. Read the PROGRESSIVE DEMOCRAT Newsletter

      by mole333 on Sat Feb 12, 2011 at 07:40:47 AM PST

      [ Parent ]

      •  I didn't phrase the question well (6+ / 0-)

        I know that they did their work independently.  I'm just wondering about the relationship between their findings.

        And yes, occasionally I've wondered if Mendel's law is as immutable as once it seemed.  And I'm wondering if that's the essence of mutation.

        Did I phtase the question better?

      •  Mendel sent a copy of his article to (2+ / 0-)
        Recommended by:
        mole333, G2geek

        Darwin — who didn't get around to reading it. It was found in his things after his death with it pages still uncut.

        I'll bet if Darwin had read it he would have grasped its importance and fitted it into his work. His own hypothesis, so labeled, was laughably bizarre, even to Darwin himself.

        I'll bet, had Darwin read it he would have immediately invited Mendel to visit him. What a wonderful meeting that would have been. I believe they would have collaborated on further work.

        Later when Mendel work was rediscovered and more besides, the scientists involved over applied it to Darwin's theory and deflected the study somewhat considering that mutation preceded change rather than changed behavior "driving" the mutations to become fixed.

        I'm asking you to believe. Not in my ability to bring about real change in Washington ... I'm asking you to believe in yours. Barack Obama

        by samddobermann on Sun Feb 13, 2011 at 05:31:31 AM PST

        [ Parent ]

      •  Don't continue to slander Mendel. (1+ / 0-)
        Recommended by:
        G2geek

        This falsehood was started by statistical maven Fisher in the 1930s. Fisher simply used the wrong statistical method to analyze the data.  Accessible explanation  points out his and followers errors. This was partly due to the misunderstanding of biology and genetic principles by Fisher.

        I don't dislike all conservatives... mainly just the ones that vote Republican.

        by OHdog on Sun Feb 13, 2011 at 05:59:27 AM PST

        [ Parent ]

    •  Gregor Mendel was a little later (5+ / 0-)
      Recommended by:
      bronte17, mole333, Cedwyn, furi kuri, marykk

      and also he was a little more isolated.  I don't think Darwin ever came across his work - IIRC, Mendel's work remained hidden until the 1880s or even later, after Darwin passed.  

    •  Mendel and Dawin (2+ / 0-)
      Recommended by:
      OHdog, marykk

      Mendel did read Darwin but was too narrowly focused on his own research agenda to grasp Darwin's full relevance. There is a copy of the Origin of Species in the Brno/Bruenn monastery library with underlinings and marginal notes in Mendel's handwriting, mainly for passages on the mysteriousness of variation and on peas.

      Mendel's isolation has been exaggerated. He was at the core of Austro-Hungarian intellectual life.

  •  Thanks for this (10+ / 0-)

    I hate to veer into politics after reading this great summary, but one of the many ways that the Republican Party discredits itself is by its tacit support of evolution denial. You don't see this to any where near this extent in right wing parties in other developed countries. The deniers do not have the most remote understanding of the mountains (hell, planet) of evidence supporting evolutionary theory. Evolution is part of life itself, ever branching and dividing into further "endless forms most beautiful".

    "The only thing we have to fear - is fear itself." - Franklin Delano Roosevelt

    by orrg1 on Sat Feb 12, 2011 at 07:33:34 AM PST

  •  Happy Darwin Day! (9+ / 0-)

    As ring species go, I prefer the Ensatina salamander in California.  It is such an elegant display of evolution in action.  Whenever I hear a creationist question where the species to species transitions are, that is my response.

  •  As Neil de Grasse Tyson said... (12+ / 0-)

    "The thing about science is it's true, even if you don't believe in it."

    •  Heh... (7+ / 0-)

      I use a variation of that:

      Evolution happens whether you believe in it or not.

      FREEDOM ISN'T FREE: That's why we pay taxes. Read the PROGRESSIVE DEMOCRAT Newsletter

      by mole333 on Sat Feb 12, 2011 at 07:48:41 AM PST

      [ Parent ]

    •  i love him (5+ / 0-)

      he is so effing funny.

      Judging from picturebooks, apparently Heaven is a partly cloudy place. - Rilo Kiley

      by Cedwyn on Sat Feb 12, 2011 at 07:55:34 AM PST

      [ Parent ]

    •  I love that! (6+ / 0-)

      "The thing about science is it's true, even if you don't believe in it."

      I like that almost as well as:

      "Nature bats last"

    •  Well, technically science (2+ / 0-)
      Recommended by:
      samddobermann, daulton

      isn't about "Truth," particularly in something like a general theory and its supporting framework. There are facts - observable, measurable, quantifiable. All sane people agree the sun 'rises' in the east and 'sets' in the west. There have been a number of different explanations ('theories') about why that is, ever more accurately predictive, until we got all the way to accurate enough to go to the moon (and planets more far-flung) and find exoplanets in distant star systems.

      But the "truth" is that our empirical sensory equipment (plus some darned nifty technological extensions) and the brains that come attached are limited by the fact that we evolved on this planet to sense and understand what our environment here presents for us to sense and understand. So there's always going to be 'more' for us to discover, and reconfiguration of theories about how those discoveries fit into the picture. Occasional 'revolutions' where something quite different becomes the Standard Operating Theoretic.

      Physics has been waiting for its 'revolution' for decades. Since the most accurately predictive theory ever devised by human beings [RQFT] started acting weird at high energies. So far, the competing theories suffer a lack of confirming evidence and nobody knows how to obtain any. But they're pretty sure by now that there are more than 3+1 dimensions comprising the totality of reality. We just don't perceive them and don't know how to test for them. It's the math that tells us they must exist.

      Religion deals in Absolute Truths. Science deals with evolving knowledge. Close enough to small-t "truth" to suffice FAPP [For All Practical Purposes], but not the object of deep emotional reverence and blind faith some want to invest in it. Almost like an alternative to gods/God. Human nature, which we earned honestly, the hard way. ;-)

      •  Facts are measurements... (1+ / 0-)
        Recommended by:
        mole333

        .... Hypotheses are predictions about the measurements that can be made under specified circumstances.  Theories are big-picture understandings that both arise from supported hypotheses and give rise to further testable (falsifiable) hypotheses.  

        •  Wow (1+ / 0-)
          Recommended by:
          G2geek

          Wells said. I think this statement should be part of every Middle School science course.

          FREEDOM ISN'T FREE: That's why we pay taxes. Read the PROGRESSIVE DEMOCRAT Newsletter

          by mole333 on Mon Feb 14, 2011 at 05:49:00 AM PST

          [ Parent ]

          •  philosophy of science spoken here. (1+ / 0-)
            Recommended by:
            mole333

            Yeah I'd love to teach it to Middle Schoolers or write it into something they use in class.  

            There are an awful lot of adults out there who could use to learn the basics too.   Sadly.  

            Then also, the point about "support" vs. "proof," and the importance of falsifiability, and the whole Keatsian negative capability thing where you deliberately go after your preferred hypothesis to see if you can falsify it, etc. etc.  

            We can say that the universe is a messy place where randomicity plays a major role and there are no absolute certainties: and from this admitted humility in the face of nature at-large, we can predict to within a half hour when a space vehicle launched from Earth will reach Jupiter.  

  •  Thanks for the diary and for referencing (4+ / 0-)
    Recommended by:
    mole333, samddobermann, Cedwyn, marykk

    this book in your bibliography:

    Browne, Janet; The Power of Place: Charles Darwin, the Origin and After, Knopf, 2002.

    I am in the process of reading it and the book reads more like a novel than a biography.  Browne did a lot of research into Darwin's life and she has portrays Darwin as a real person - with doubts, fears and questions about his discovery.

    Also, the book delves extensively into the culture at Darwin's time and the people who influenced his thinking. It is a long book, but well worth reading if one wants a better understanding of Darwin and the world he lived in.

    •  Wasn't there something about (1+ / 0-)
      Recommended by:
      ivorybill

      Darwin being reticent lest he run afoul of his wife's religious beliefs?

      •  It wasn't only his wife's religious beliefs (2+ / 0-)
        Recommended by:
        mole333, marykk

        it was the religious beliefs prevailing at the time.  People couldn't believe that natural selection could occur on its own - without some kind of creator.  They believed that any change should have a "purpose" and that there had to be a god to guide that change/purpose.

        •  Too bad they couldn't envision (3+ / 0-)
          Recommended by:
          LynChi, mole333, ivorybill

          an almighty who could conceive something as miraculous as biochemistry, and then just sit coolly back and watch it unfold.  

        •  different types of rejection of evolution: (1+ / 0-)
          Recommended by:
          mole333

          What you're describing is one form: inability to believe that all this could occur without a deity to create it.  

          However that seems to have been overcome in Europe at least.  

          There is another type of rejection, that I think is more or less unique to American culture, which is the refusal to acknowledge that we are part of the lineage that includes "lower" animals, particularly monkeys.  

          Monkeys look enough like us to be recognizable as related, once you hear how nature does it.  But they also have plenty of objectionable behaviors that appear to be expressions of the pure Freudian id.  They fling their poo at each other (and at humans), they are sexually promiscuous or at least very often publicly sexual, and they masturbate frequently even with humans watching.  

          To a puritan culture, those things are appalling to the point of being unspeakable.  So the puritanical rejectionism is very much rooted in puritan morality, particularly with regard to sex.  That may very well explain how it is that rejection of evolution in the US took on the entire dimension of being associated with rejecting the idea that we are related to monkeys.  

      •  He was reluctant to publish (5+ / 0-)
        Recommended by:
        LynChi, mole333, orrg1, marykk, Joieau

        in part because he never felt he had enough data.  He avoided any statements about his own religious belief or lack thereof, although he privately wrote about his loss of religious faith.  

        Darwin and his wife lost their daughter, and she was broken with grief (he was too, but as this deepened his wife's faith, it shook his).  He wrote that he would never do anything to undermine her faith, as she needed it to survive this loss.  So it's not that he was intimidated, it's that he was compassionate toward his wife.  There was a small section on this in the great Darwin exhibit that passed through the Field Museum a couple years ago.  I thought it was exactly the right way to negotiate lack of faith with others around us who have faith - never lie about believing something, but never, ever belittle another's faith or push them to abandon it.  

        •  Beautifully put. (3+ / 0-)
          Recommended by:
          mole333, ivorybill, Joieau
        •  Darwin's religion (0+ / 0-)

          Actually, the Origin of Species is full of religious statements. In the concluding chapter, a 'creator' breathes life into the original species. IN chapter 6, Darwin implied that fundamentalists simply have an overly constrained and simplistic view of god, and don't give him enough credit.

          •  and this would be the ground for pluralism. (2+ / 0-)
            Recommended by:
            mole333, Matthias

            Atheists and agnostics would have no problem getting along with theists whose position is something along the lines of "natural selection is correct, evolution occurs, and we believe that there is a Creator that set the wheels in motion and subtly guides the progress of nature."  

            To a rationalist, such a statement is merely the addition of an extra and unfalsifiable explanatory mechanism into the picture.  It may not accord with Occam, but it's not intrinsically harmful in that it does not deny the explanatory mechanisms supported by science.  

            If that were the extent of the differences of opinion, everyone could get along nicely.

            What throws a proverbial monkeywrench (heh) into the works is when American fundamentalists do something particularly unique, by insisting that Darwin is flat-out wrong, natural selection and evolution are flat-out wrong, and all that we see can be accounted for by the actions of a deity per one or another Biblical accounts.  

            This is the danger of all forms of fundamentalism: they attempt to monopolize a domain of truth in such a manner as to refuse to acknowledge anything that differs from it to even the slightest degree.  

            And the results we observe are the ongoing "monkey wars" whereby powerful religious interests in the US seek to oppose something for which there is almost as ample support as there is for Newtonian physics at the macroscopic scale.  From our perspective they may as well be trying to oppose the laws of gravity or thermodynamics.

            And yet we are stuck having to fight this battle over and over and over again.  

            •  Setting the wheels into motion (1+ / 0-)
              Recommended by:
              G2geek

              Since there has yet to be any satisfying scientific theory that explains how the whole universe thing (seemingly a really severe violation of the Second Law of Thermodynamics) got started, it seems to me that "God turned on the light switch and said, 'Let there be light.'" Is as viable a hypothesis as any. Not saying I buy that hypothesis, but I am not sure science has come up with better. That is the main reason I continue to label myself agnostic (when I don't call myself a Jew with Buddhist leanings) rather than atheist. I don't see that science can rule out a role for a Creator at the very beginning with our current knowledge.

              FREEDOM ISN'T FREE: That's why we pay taxes. Read the PROGRESSIVE DEMOCRAT Newsletter

              by mole333 on Mon Feb 14, 2011 at 05:52:57 AM PST

              [ Parent ]

              •  yes, exactly. (1+ / 0-)
                Recommended by:
                mole333

                There are a few places we can't get to with science, one of those (so far) being the origin of the universe to begin with.  

                But I'm wary of "God of the gaps" explanations, which are more like black-box hypotheses.  There should be some way to indirectly infer the existence or otherwise of the fundamental premise that is necessary for a deity to exist in the first place: that there can be a mind without need of a brain to support its existence.  (ESP doesn't do it, because it behaves in a manner that is closely in accord with theories of nonlocality, and is in other ways lawful in such a manner as to not require divergence from the material monist theory of mind.)  (Hint: look for instances of near-death experiences where the individual reports conscious experiences with objective correlates at a time when measurements show their brain activity was zero or far below the threshold that would be expected to support consciousness.)

                Another place to go with this:  Wheeler's "it from bit" theory of information as the singular fundamental constituent of all else: universe as thought rather than as thing (and Wheeler was ferociously opposed to anything even remotely approaching woowoo).  Self-organizing information is basically a mind, by definition.  In that case the necessary outcome is a kind of pantheism or at least pan-psychism: universal mind inherent in everything.  

    •  Read it some time ago (1+ / 0-)
      Recommended by:
      LynChi

      But I do remember it being good.

      FREEDOM ISN'T FREE: That's why we pay taxes. Read the PROGRESSIVE DEMOCRAT Newsletter

      by mole333 on Sat Feb 12, 2011 at 07:49:25 AM PST

      [ Parent ]

  •  The truth about gravityism (5+ / 0-)
    1. Gravity is just a theory.
    1. In fact there are TWO theories: Newton's and Einstein's. (Three if you count Aristotle.) If pointed headed scientists can't even agree, what are we supposed to believe?
    1. It ain't in the Bible.
    1. There is a conspiracy among all the worlds' scientists to promulgate the gravity lie in order to glom onto government grants. (See NASA.)
    1. We owe it to our children to present them with all viewpoints and let them decide.

    Anti-gravityists of the world arise!  Seriously.  Just float up in the air!

    •  It's in the bible! (1+ / 0-)
      Recommended by:
      daulton

      How do you think Jericho's walls could fall down if God hadn't created gravity!

      FREEDOM ISN'T FREE: That's why we pay taxes. Read the PROGRESSIVE DEMOCRAT Newsletter

      by mole333 on Sat Feb 12, 2011 at 07:56:08 AM PST

      [ Parent ]

      •  Nope! Just substances seeking their own level. (0+ / 0-)

        Per Aristotle. He was endorsed by the church, after all.

      •  archeologists have no evidence that Jericho's (2+ / 0-)
        Recommended by:
        daulton, OHdog

        walls fell ever. There is some evidence the proto- Hebrew tribes speaking the same language and generally worshiping the same gods as the Canaanites (particularity in the south)much exaggerated their tales of "conquest".

        fact does not require fiction for balance (proudly a DFH)

        by mollyd on Sat Feb 12, 2011 at 08:22:23 AM PST

        [ Parent ]

        •  Yep (6+ / 0-)

          Most fascinating thing to me about modern research into the ancient Israelites is the very first thing that changed in the group. Their pottery, worship, technology, everything was just plain Canaanite. But suddenly pig bones disappeared from their trash heaps.

          The emergence of a separate, proto-Jewish consciousness was heralded by the decision to  eschew pork.

          Interestingly I found out some time back in an obscure reference in the book Salt by Mark Kurlansky that ancient Egyptians avoided pork as unclean. Ancient Egyptians avoided pork but Canaanites didn't, so it seems like a possible Egyptian influence on one small, isolated, backwards group of Canaanites that got the Jewish ball rolling.

          Got me wondering whether that whole Exodus story actually had some degree of historical truth behind it. Of course not on the scale it is written in, but a small historical kernel within the myth. After all "Moses" is not a Caananite name but half an Egyptian name (as in Amose, Kamose, Ramose).

          FREEDOM ISN'T FREE: That's why we pay taxes. Read the PROGRESSIVE DEMOCRAT Newsletter

          by mole333 on Sat Feb 12, 2011 at 08:31:26 AM PST

          [ Parent ]

          •  Since Egyptians didn't build with slaves (3+ / 0-)
            Recommended by:
            mole333, daulton, marykk

            but a Semitic ( not Hebrew or Canaanite) tribal people living in Gaza at the right historical period did use slaves. It is more likely that is where the story of Exodus happened.

            fact does not require fiction for balance (proudly a DFH)

            by mollyd on Sat Feb 12, 2011 at 08:35:18 AM PST

            [ Parent ]

            •  Two stories in one (2+ / 0-)
              Recommended by:
              daulton, marykk

              Exodus is believed to combine two narratives, one about a forced expulsion and one a voluntary exodus.

              But I have always wondered if the story additionally or instead reflects the expulsion of EGYPTIANS from Canaan. Egyptian influence waxed and waned, and there were expressions of independence, particularly among that troublesome group the Hapiru. The old theory of Hapiru = Hebrew is generally discredited these days, but I still feel there could be a link and believe an intermediate theory that "not all Hapiru were Hebrew but some Hebrews were Hapiru."

              Overall I do not believe that the bible reflects historical reality any more than the Bagavad Gita or Iliad do. They are, in essence, historical fiction, using real places and some real people to create a good story. But the more I have thought about it, the more an influx of Egyptian people or at least strong influence into a Canaanite population is the reality behind Exodus.

              "Moses" clearly being an echo of a real, Egyptian person

              the rejection of pork in Egypt and the proto-Hebrews but not in between

              the two strange examples of nascent monotheism (Atenism and proto-Judaism) arising at a similar time and place (both within a dominant polytheistic context)

              The words Hapiru and Hebrew

              All is circumstantial and the first actual mention of Israel is somewhat later, but it suggests something real behind Exodus.

              FREEDOM ISN'T FREE: That's why we pay taxes. Read the PROGRESSIVE DEMOCRAT Newsletter

              by mole333 on Sat Feb 12, 2011 at 08:44:36 AM PST

              [ Parent ]

          •  There are historical things in the bible. There' (2+ / 0-)
            Recommended by:
            daulton, marykk

            no point in rejecting outright.  But it is history passed through generations of oral history and conflicting versions of the stories when they were finally written down. (That's why there are 2 versions of the genesis myth in the bible.

            The book of Ruth is regarded as a novel by bible historians.

            It's really not that the bible is untrue, it's that it is foolish to believe the bible is the literal word of god.

            HylasBrook @62 - fiesty, fiery, and fierce

            by HylasBrook on Sat Feb 12, 2011 at 08:42:58 AM PST

            [ Parent ]

            •  As I say above... (2+ / 0-)
              Recommended by:
              mollyd, daulton

              Overall I do not believe that the bible reflects historical reality any more than the Bagavad Gita or Iliad do. They are, in essence, historical fiction, using real places and some real people to create a good story. But, as with the discovery of Troy, you can't ignore the bible. But too often people use the archaeology to try and "prove" the bible is correct. That has led to some real misconceptions that are still trying to be worked out.

              FREEDOM ISN'T FREE: That's why we pay taxes. Read the PROGRESSIVE DEMOCRAT Newsletter

              by mole333 on Sat Feb 12, 2011 at 08:47:09 AM PST

              [ Parent ]

            •  There are at least 4 writers in the first 5 books (3+ / 0-)
              Recommended by:
              mole333, daulton, OHdog

              One from the North(more formal and a monotheist, one from the South (more relaxed and a polytheist) ;the great redactor who combined the almost 2 full versions of each story, and a priest who came along later and added many ritual elements.

              fact does not require fiction for balance (proudly a DFH)

              by mollyd on Sat Feb 12, 2011 at 08:51:42 AM PST

              [ Parent ]

          •  Pig to no pig illustrates one evolutionary (0+ / 0-)

            path of religion. When an animal or behavior becomes taboo it often is because that animal was a totem animal and particularly revered by group that has been incorporated into the larger whole. This link is eventually lost and the taboo is what is retained particularly if coincidentally there is some minor advantage such as reduction of trichinosis, etc.

            I don't dislike all conservatives... mainly just the ones that vote Republican.

            by OHdog on Sun Feb 13, 2011 at 06:11:19 AM PST

            [ Parent ]

            •  over time the "minor advantage" adds up to... (1+ / 0-)
              Recommended by:
              OHdog

              ... a natural selection advantage.  

              The Jewish rejection of pork and shellfish, plus a few other elements in Jewish dietary and hygienic laws, add up to a pretty decent natural selection advantage over cultures that had none of those elements.  

              The results of which have contributed to the longevity of a tiny and persecuted tribe that would otherwise have been expected to disappear entirely a couple thousand years ago.

              •  Yes and we expect that is true of the food and (0+ / 0-)

                hygiene choices of other cultural groups as well. For instance soaking corn in lye water destroys some of its amino acids but at the same time creates a more balanced and healthy protein. The Native Americans practicing this may not have overtly realized this but hominy and grits was still a staple.

                I don't dislike all conservatives... mainly just the ones that vote Republican.

                by OHdog on Mon Feb 14, 2011 at 09:54:07 PM PST

                [ Parent ]

    •  A creationist will tell you... (4+ / 0-)
      Recommended by:
      mole333, daulton, ivorybill, HylasBrook

      that gravity is a law.  I once tried to explain to one the difference between a law and a theory and the difference between the Law of Gravity and the Theory of Gravity, but she would have none of it.

    •  Hey, gravity is just a social construct! (2+ / 0-)
      Recommended by:
      mole333, daulton

      It depends entirely on the point of view, and socio-political context of the person experiencing it!

    •  The Newtonian World was more Comforting (5+ / 0-)

      I'm often cautious, when I hear fellow defenders of science bring up gravity.

      It is a much safer bet to bring up electro magnetism, because at least that can be reasonably explained.

      Once you get into gravity, you begin dealing with mysteries which become increasingly harder to explain.  Once you utter the following phrase, you are pretty much screwed.

      "Well you see, space and time are actually curved."

      For some reason we are comfortable with gravity at a glance, but stare too long and you'll figure out how little you truly know.

    •  have i got news for you. (1+ / 0-)
      Recommended by:
      mole333

      Geocentric astronomy is still alive and kicking, and a bunch of believers in it had a conference shortly after election day 2010.  

      They even build geocentric orreries.  

      And though we may think them foolish to the point where we expect them to vanish from the scene, no doubt our predecessors felt likewise about the anti-Darwinists in their own time.  

      So the thing to do here is to go proactive, go on the attack, and apply vigorous ridicule to prevent the geocentrists from gaining any ground whatsoever.  

      We ignore them at our peril.  

  •  A remarkable diary. Hotlisted, (3+ / 0-)
    Recommended by:
    mole333, ivorybill, marykk

    tipped and recommended!

    You could also mention the Friends of Charles Darwin. If you sign up you are entitled to the postnominal FCD designation!

    Exspectamus et vigilamus: quod nolite somnamus.

    by tapu dali on Sat Feb 12, 2011 at 07:52:30 AM PST

  •  Geological Evidence was Crucial to Darwin as well (8+ / 0-)

    Darwin wasn't only part of a revolution in biology, but was also heavily influenced by the transformation occurring in geology.

    Geology has never been as sexy as biology or physics (which would make its mark in the next century).

    But still geology was the spearhead for everything the naturalists achieved.  Geologists moved the discussion from thousands of years to millions of years, before Darwin ever picked up a pen.

    The fossil records indicated thousands of species, which had become extinct long before the time of man.  This clue was crucial to Darwin's work.

    To understand evolution you must understand probability.  A casual poker player may go their whole life never seeing a royal flush.  A 52 card deck needs to be dealt 650,000 times, before you can say it is likely a royal flush will occur.

    Likewise of all mutations within a species, very few will survive and reproduce.  Nature had to deal a lot of hands, before genetic variance could occur.

    Until one can comprehend hundreds of millions of years (or at least accept that they are incapable of comprehending), they'll never be able to fully appreciate the likelihood of evolution.

    It wasn't anything that occurred against the odds, because over a long enough period of time all odds are reduced to near certainty.

    It was when Darwin realized this, that he was able to approach the problem differently.

    •  Absolutely! (4+ / 0-)
      Recommended by:
      LynChi, ivorybill, Dr Teeth, Joieau

      Wish I knew more about the geology end of it, but biology is my specialty. But I did a couple of years ago read a great book on Krakatoa (by Simon Winchester) which included a great deal of the history of geology. Excellent book. Highly recommended.

      FREEDOM ISN'T FREE: That's why we pay taxes. Read the PROGRESSIVE DEMOCRAT Newsletter

      by mole333 on Sat Feb 12, 2011 at 08:00:57 AM PST

      [ Parent ]

    •  OT but the geological equivalent of Darwin (4+ / 0-)
      Recommended by:
      mole333, Dr Teeth, HylasBrook, Joieau

      I believe was Wegener and his theory of continental drift or plate tectonics.

      The Canadian geophysicist J Tuzo Wilson, with whom I studied, was in the 60s an early exponent of this then controversial idea.

      Exspectamus et vigilamus: quod nolite somnamus.

      by tapu dali on Sat Feb 12, 2011 at 08:06:09 AM PST

      [ Parent ]

      •  Darwin was heavily influenced by Charles Lyell (6+ / 0-)

        the first great British geologist, at the very start of the 19th century.  Lyell also had to contend with people who were unwilling to accept the great antiquity of the earth, so he carefully constructed his argument based on gradualism - gradual deposition of sediments, extrapolating back in time processes that are readily seen today.  He was fighting catastrophists, because the dominant theory before then was that all sediments were laid down by the great flood.

        Of course, this does not take into consideration major events like asteroids or periods of volcanism, techtonic drift, etc.  Lyell could only fight one battle at a time, so he pushed gradualism as hard as he could.  Darwin picked up on this and one of the problems he faced was trying to determine the speed of evolution, and major mutations that seemingly don't have intermediate steps.  More recent biology accepts punctuated equillibrium; rapid change in small isolated populations, and occasional big impact from small changes in one or two regulatory genese.  But Darwin was very much cut out of the same cloth as Lyell and emphasized the vastness of time and gradual change.

      •  And how many of us (4+ / 0-)
        Recommended by:
        mole333, samddobermann, ivorybill, OHdog

        schoolchildren back in the '50s and '60s noticed that Africa looked like it was a separated part of South America, and were dismissed (with prejudice) for seeing pattern where "Science Knows" that no pattern exists?

        I was as glad when plate tectonics took over (Duh! Take THAT Mrs. Cole!) as I was when the Big Bang 'revolution' happened. My Dad, who worked on the Apollo project, was a Banger early on. It just kept showing up in the equations, no way around it. Ah, well. There were very influential astronomers/astrophysicists who clung to the belief that there was only one galaxy, long after it was demonstrated conclusively that there were More...

        •  When this was brought up in my 6th grade class the (2+ / 0-)
          Recommended by:
          G2geek, Joieau

          teacher, to her credit, used it to explain, that if it was true, that scientists could find out why and how it happened. That opened all, or most, of our eyes to the creation of science.

          I don't dislike all conservatives... mainly just the ones that vote Republican.

          by OHdog on Sun Feb 13, 2011 at 06:18:25 AM PST

          [ Parent ]

    •  He also presaged nuclear fusion (3+ / 0-)
      Recommended by:
      mole333, ivorybill, Dr Teeth

      He admitted that if contemporary solar theories were true, the sun had not been around long enough for evolution to have worked.

  •  Thank you for this detailed diary (5+ / 0-)

    I cannot believe evolution is even remotely controversial. The proof is so incredibly solid, that I cannot comprehend any argument against it. It's akin to disputing gravity.

    One of the most mportant things for people to understand is the incredibly large timescales. Simple prokaryotes existed for billions of years before they began to develop into complex cells and organisms. If you think of it in those terms, it makes a lot of sense.

    But back to evolution in general...it just angers me when people try and disprove it. There is no scientific mechanism that could possibly replace it. There is not a single reputable biologist who disagrees with the tenets of evolution, How can you possible be skeptical towards a theory that has withstood rigorous examination and testing for 150 years, and has been completely validated by all sectors of biological science?

    It truly boggles the mind.

    What matters is not wealth, or status, or power - but how well we have loved, and what small part we have played in bettering the lives of others. - Pres. Obama

    by Raineee on Sat Feb 12, 2011 at 07:58:33 AM PST

  •  The mark of great science (5+ / 0-)

    is that it is predictive.  To Darwin's great credit and genius, the predictions made by his theory have been born out.  It predicted that a mechanism would have to exist to make it possible for traits to be inherited, and that the mechanism would have to be slightly imperfect.  Sure enough, the DNA molecule was found, which provided a means for nearly, but not completely, perfect inheritance of traits.  The theory predicted that the earth would have to be old enough to explain the enormous variations in living things now in existence. This required that the sun be powered by a source of energy far greater than those known in Darwin's time, chiefly chemical and gravitational. Sure enough, nuclear fusion and the concept of conversion between mass and energy were discovered, making available the time required for evolution to occur.

    At the same time, findings that would discredit evolution, such as finding fossils unexplainably present in the wrong strata, have never been found.

    All life forms are the product of a process that did not require intelligent intervention, for as far back as we have been able to examine.

    "The only thing we have to fear - is fear itself." - Franklin Delano Roosevelt

    by orrg1 on Sat Feb 12, 2011 at 08:01:45 AM PST

  •  Best wishes, Chuck (4+ / 0-)
    Recommended by:
    mole333, ivorybill, kovie, marykk
    Love, Uncle Gombo
             Primate Pavillion
             Woodlawn Park Zoo
             Seattle, Washingtom

    _"George, when I want your opinion I'll give it to you!" -Dick Cheney 2002_

    by oopsaDaisy on Sat Feb 12, 2011 at 08:11:40 AM PST

  •  Secular Humanists regard Darwin's (5+ / 0-)

    birthday as a holiday worth celebrating.  Many of us go out to dinner in a restaurant to acknowledge the life's work of a man who helped us take a realistic view of how humans are related to the rest of the world.

    HylasBrook @62 - fiesty, fiery, and fierce

    by HylasBrook on Sat Feb 12, 2011 at 08:12:05 AM PST

  •  Yeah but how'd the moon get there? (1+ / 0-)
    Recommended by:
    daulton

    How'd it get there?

    How'd it get there?

    How'd it get there?

    How'd it get there?

    How'd it get there?

    How'd it get there?

    How'd it get there?

    .
    .
    .

    "Those who stand for nothing fall for anything...Mankind are forever destined to be the dupes of bold & cunning imposture" --Alexander Hamilton

    by kovie on Sat Feb 12, 2011 at 08:23:28 AM PST

  •  Hear Hear!!! n/t (1+ / 0-)
    Recommended by:
    mole333

    The Ongoing Drama of Palin's Place - for your latest in faux outrage and professional victomhood.

    by delmardougster on Sat Feb 12, 2011 at 08:38:29 AM PST

  •  Dude (2+ / 0-)
    Recommended by:
    mole333, daulton

    Why oh why did you have to post this now? Oh well, I guess I'll just have to read Richard Dawkins during the transition.

    You better check yourself chunky.

    by MeMeMeMeMe on Sat Feb 12, 2011 at 08:38:39 AM PST

  •  And for those that missed it (2+ / 0-)
    Recommended by:
    mole333, daulton

    Scopes Monkey Trial - How it played out in one family

    See ya'll on the flip side after we evolve into DK 4.0.

    Peace,

    Andrew

    "Do what you can with what you have where you are." - Teddy Roosevelt

    by Andrew C White on Sat Feb 12, 2011 at 08:55:23 AM PST

  •  Some people? (0+ / 0-)

    I thought punctuated equilibrium was the minority position in scientific circles.

    The Raptor of Spain: An Alternate Histoyr Blog
    From Muslim Prince to Christian King (Updated Sept. 8!)

    by MNPundit on Sun Feb 13, 2011 at 04:54:05 AM PST

  •  about violating the 2nd law of thermodynamics: (1+ / 0-)
    Recommended by:
    mole333

    Over time evolution coincides with a tendency toward increase in the diversity and complexity of species and their interrelationships.  This would seem to violate the 2nd law of thermodynamics:  how do you get syntropy in a universe bound by entropy?

    The answer is that organisms are dissipative structures: energy converters that feed off prevailing entropy-flows to produce localized syntropy.  The prevailing entropy-flow for Earth is solar radiation.  Incoming sunlight provides the basis for net energy gain by organisms, that in turn drives not only their metabolisms, but the entire process of evolution.  

    Organisms that live outside the reach of sunlight, for example extremophiles on the deep ocean floor, utilize the heat energy available from the Earth's molten interior, made available through hydrothermal vents where the heat transfers to the ocean water.  This process could hypothetically occur on planets further from a star, provided there was a transport medium: water locked under an icy crust, or some other fluid.  It provides the basis for hypotheses about life further out in our solar system.

    Further, generalizing the hypothesis about other energy sources, we can look at the effect of gravity between large planets such as Jupiter, and their satellites such as Europa.  The gravitational pull of the planet, against the angular momentum of the satellite, could produce repetitive stresses on the satellite in a manner that adds enough net energy as to translate to sufficient heat to provide an entropy gradient that organisms can utilize for metabolism.  

    Thus, the 2nd law of thermodynamics is not violated: the complexity and diversity of evolution is driven by organisms tapping whatever entropy gradients may exist in their environments.

    And a few billion years later, you're sitting here reading this.

    •  Yep (1+ / 0-)
      Recommended by:
      G2geek

      Well put.

      I think what people fail to grasp is that local violations of the 2nd Law are common as long as the overall balance is towards Entropy.

      Then again this seems to fit right wing views of the world. Make local blips of supposedly good economic times with trickle down economics, but underneath it feeds of a decline in long-term, overall economic stability. Republican economic policies seem to locally violate the 2nd Law at the expense of losing economic stability in the long run.

      FREEDOM ISN'T FREE: That's why we pay taxes. Read the PROGRESSIVE DEMOCRAT Newsletter

      by mole333 on Mon Feb 14, 2011 at 05:56:30 AM PST

      [ Parent ]

  •  Family tree of life (1+ / 0-)
    Recommended by:
    mole333

    One of the strongest arguments for evolution is that living things fit into a genealogy. I do not think this has received enough publicity.
    It is really not hard to argue that H. sapiens and the orchid Cattleya labiata have a common ancestor.
    We share a considerable biochemical heritage with all flowering plants that have been investigated. That includes a common genetic code for encoding proteins in genes. Vitamin B1 is a co-enzyme for a biochemical reaction found in a very wide range of living things. Do orchids have haemoglobin? None, that I know of, but they have chlorophyll, with very few exceptions. Both pigments have a ring system shaped like a Maltese cross, made of carbon and nitrogen atoms. Haemoglobin has an iron atom in the center, but chlorophyll instead has a magnesium atom. The 2 pigments serve very different purposes but use common material.
    As a matter of fact, Charles Darwin wrote a paper on the orchids, in which he noted the evidence for descent from lily-like plants. Much more recently there was a paper on gene comparisons among various flowering plants. It indicated that the genera Oncidium and Neuwiedia are more closely relaed to one another than to other monocoteyledons. They are about as unrelated as 2 orchids can be. Neuwiedia is of scientific interest as a primitive orchid, but has no interest for most orchid growers.

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