Darwin's "Theory"

Darwin's  "Theory"

There are 2 definitions of theory

Unfortunately they mean opposite things

Theory
As Fact Not Fantasy

The disingenuous take advantage of confusion, so after over 150 years, Darwin's Theory of Evolution is still very misunderstood by the public.

One thing that seems to trip up people's thinking is the meaning of the word "theory". As in "It's only a theory.". So let's start by making this point clear.

Let's get this straight Definitions Theory (thee-uh-ree, theer-ee) noun, plural the·o·ries 1. A coherent group of tested general propositions, commonly regarded as correct, that can be used as principles of explanation and prediction for a class of phenomena: Einstein's theory of relativity. Synonyms: principle, law, doctrine. 2. A proposed explanation whose status is still conjectural and subject to experimentation, in contrast to well-established propositions that are regarded as reporting matters of actual fact.  Synonyms: idea, notion hypothesis, postulate.

Darwin's Theory of Evolution The definition number 1 kind! Natural Selection is a law of nature The Theory of Evolution in 2 minutes

Theory in Use In technical or scientific use, Theory, principle, and law represent established, evidence-based explanations accounting for currently known facts or phenomena or for historically verified experience: the theory of relativity, the germ theory of disease, the law of supply and demand, the principle of conservation of energy. Often the word law is used in reference to scientific facts that can be reduced to a mathematical formula: Newton's laws of motion. In these contexts the terms theory and law often appear in well-established, fixed phrases and are not interchangeable. In both technical and nontechnical contexts, theory can also be synonymous with hypothesis, a conjecture put forth as a possible explanation of phenomena or relations, serving as a basis for thoughtful discussion and subsequent collection of data or engagement in scientific experimentation in order to rule out alternative explanations and reach the truth. In these contexts of early speculation, the words theory and hypothesis are often substitutes for one another: Remember, this idea is only a theory/hypothesis; Pasteur's experiments helped prove the theory/hypothesis that germs cause disease. Obviously, certain theories that start out as hypothetical eventually receive enough supportive data and scientific findings to become established, verified explanations. Although they retain the term theory in their names, they have evolved from mere conjecture to scientifically accepted fact. (Dictionary.com)

The Facts Of Evolution

On the Origin of Species What Defines a Species? A tricky question and controversial, it would take an entire blog post just to address this question. I will give a quick and dirty definition here but a future post will examine species in more detail. In general biologists have used a rule of thumb as a way to determine what is a species. When individuals are so different, either physically or genetically, as to be unable to reproduce viable off-spring together (and again this can be for a host of reasons), they are defined as distinct and separate species. In biological science, the form of an organism is called a phenotype. Phenotype being the sum of observable physical and behavioral characteristics manifested by an organism. The phenotype comes mainly from chemically coded instructions known as genes. This is the molecular coding known as DNA. The DNA genome, the full set of chromosomes, is called a genotype. The genotype is the genetic constitution (number of chromosomes, etc.) present in every organism of that population or species, It is all the alleles for structure, metabolism, development as well as the regulatory genes in that type of organism. Epigenetics Genes don't do everything It is of note, that it is possible for organisms to have the same genotype but different phenotypes. This is where epigenetics comes in. The same DNA can be regulated differently due to epigenetic markers associated with environmental or developmental influences. Now, the reverse is also true. Different genotypes can develop a similar phenotype simply by convergent evolution. This can happen when the different organisms' share an environment or the ecologies are similar enough to have the same types of selection pressures. There is a great deal of simultaneous continuity and change in nature. Over the course of natural history, both the living (biotic) and non-living (abiotic) most ancestral forms have changed, while in others, aspects have changed very little, if at all, over eons. The biotic and abiotic also interact and influence each other in significant ways. All this, over geological time, can be seen to have contributed to the diversity of life forms and the diversity of environments on Earth.

Darwin examined individuals and populations Studying modification over time In 1859, Charles Darwin published The Origin of Species. Do individuals change within a lifetimes as Lamarck had said or do only populations change over time? What is operating in the natural world that determines the populations' change? On what time scale does speciation occur? Does it happen suddenly or only gradually, over many generations? So many questions. Darwin had some insightful ideas about all of this during a long voyage on the HMS Beagle.  Darwin observed that for all phenotypes, existence has requirements for and consequences on, the reproduction of their genotype. These lead to changes in the number of certain phenotypes (kinds of individuals) and their genotypes (kinds of blueprints) being born and surviving in a population over the generations. He saw that when populations are reproductively isolated from others, these populations can eventually become more than just variations within a type. When they are only able to reproduce with their own kind, they are recognized as a true species. What is not always immediately observable or understood is how the changes in off-spring may occur. In an age before the science of genetics, Darwin didn't know about genes exactly, or how they do what they do. But was right about one thing and awfully close to another. He speculated there were gemules that came from each parent with their traits and that in reproduction the traits are inherited by the offspring. Darwin's theory wasn't really exceptional in the observation that life forms change and appear different. Many before him had noticed this. It was exceptional in that he saw a way how living "types" or species have come about and are continually changing into new stuff all the time. Beginning with the observation that in the process of life and reproduction there is modification accompanying inherited traits, some of which are adaptive, and that extinction follows insufficient reproduction. Over time, even small differences could accumulate to result in a radial change. He saw one important way the origin of species could come about based on this and the fact that not all succeed to reproduce. Darwin's expression of the process was, natural selection. These words are familiar but to many, they are understood in different ways. Many, including some biologists refer to natural selection as a mechanism. I am of the opinion that better insight comes from the view that this is pertaining to an organic process, and a mechanical metaphor is inappropriate. Selection Naturally In order to illustrate this process a mechanical process will do. Darwin mentions the selection of characteristics or traits that human domestic breeders make. There exists a variety of traits in the individuals of a population. He tries to illustrate how those individuals which have traits selected ( chosen by the breeder ), are the ones allowed reproduce and have the offspring, who in turn, carrying these traits flourish. Those without the favored traits are not preserved as breeding stock, and are therefore their traits are eliminated from any substantial contribution to the future generations. By the intervention of the breeder/selector those individuals with these traits are the ones which increase in the population. Many of their offspring strongly exhibiting the favored traits are advantaged in that, again they are the ones selected to reproduce more of their kind. This leaves even more individuals with those traits in the population. Consequently, over several generations, this has an influence on the composition of the population. The differential in their reproduction relative to others in the population results in more individuals with these traits existing in the population. Eventually the entire population can be exclusively composed of only individuals of these traits. Thus the breeders, by what traits they favor and the individuals they select to breed, can change the entire variety of traits from that present in the original population. The result can be radical divergence of type, like nothing before. The analogy used incorporates intent on the part of the breeder as selector. This is used to show what happens when certain individuals contribute more of their inherited traits to the composition of the population. Superimposing the intentional, or artificial method of selection, onto the natural shows why it is an analogy. They are not the same in every respect, only in the resulting effects in the population. Nature, as the selector of preserved traits, is not a person. Not even as abstract person and does not have intention, only consequences. The criteria are not determined by will or forethought. The nature referred to is another way of saying all the concrete consequences of real circumstance in nature, and that includes random chance. Everything that interacts with whatever exists in the context of the natural world, nature itself, will experience the consequences of that interaction. The criterion for natural selection is contributing to posterity. Individuals not surviving long enough to reproduce in the circumstances pretty much eliminates the chance to do this. Determined solely by circumstances, any and all traits which provide fulfillment of this criterion tend to be preserved. Any quality which, directly or indirectly, permits or assists this to occur is a trait considered adaptive. Any quality which accommodates, suits the circumstances. Meeting this natural criteria permits reproducing and the perpetuation of lineage concretely and traits not accommodating the natural context have the consequence of not contributing to posterity in sufficient numbers to keep that line going. Since some inherited traits will be at an advantage in this, they are likely to have a greater contribution to posterity. Neither nature, nor individuals and their offspring, have to have intent for this to occur. It is simply the consequence of the way things are. This is in spite of some effects of nature which appear to be what a conscience selection would make. That's us projecting and anthropomorphizing nature. Nature does not stand apart from the entities within it and choose which individual of what trait lives, which will die. The nature here, is the context where elimination and preservation are occurring. Even through the word selection may lead us to project our own perception of selection as a conscience process, nature, when not personified is another word for the circumstances. The process of selection, is really the consequence of circumstance. And that's always changing. Darwin did not mean to imply some plan or intent on the part of nature. A variety of traits in a population exist, a variety of circumstances determines the rate by which individuals of certain traits reproduce. Inherited traits are passed on to descendants, and if those traits do not get in the way or assist, even in the slightest, in differential reproduction, the resulting increase in numbers as they successfully reproduce in numbers going into the future, will influence the characteristics of the population. Natural selection, to many people, directly translates as the now famous survival of the fittest. This expression was coined not by Darwin but by a man named Herbert Spencer. Those that are fit survive and those that are surviving are those that are fit. Now, very different interpretations of what survival is and what being fit means are possible. If this expression is taken literally, the real meaning is confused. One may even conclude that it is not scientific since the form is one of repeating the same thing, a tautology. For one thing, this is an "expression", it was coined for effect or display. It is not a formal scientific statement and was never intended to be so. The expression does not detail the theory behind the rhetoric. Survival does not mean only that it is the individual that survives. Is that the success that is meant? Logically, then this makes it so none are, nor can ever be. No individual, survives forever. Fit by survival alone? Not how it is Taking the phrase too literally is absurd or if one were to be more cynical, downright deceitful. Regardless of why, some scientists themselves have missed the point. Individuals existing, surviving, long enough to reproduce offspring that are viable and thus are participating in the population's composition is the necessary survival. It would be more sensible and perhaps honest to take this as surviving by descendants and legacy. Those surviving to accomplish this are doing the very minimum in nature. These individuals are also " survived by " relations, and the more relations the better the chances to contribute inherited traits to posterity. Furthermore, generally the longer one lives the more opportunity for this to occur. Quite simply, the odds on their side if they successfully reproduce more offspring over many years. A component of this type of survival is the perpetuation of the genes for those traits in the descendants. The genes are the biological coding, the means to manifest traits in individuals. If those genes are not present in future generations ... it's called extinction. Darwin, living in a time when genetics was yet to be developed, referred to it as the passing on or inheritance of some particle or material which determined the characteristics which are contributed by the individual into future generations. Darwin was not quite able to nail down the most accurate process of inheritance. although it seems pretty clear that without the benefit of genetics he did appear to have a ballpark notion of the modification process of the descendants. The combination of both parents contribution of encoding material generates the variety of phenotypes manifest in populations. This variety of individuals is the essential quality that natural selection acts upon. The selection occurring may be because of a trait, but it is the individual (and descendants) that is selected. The result of this selection process eventually becomes manifest in the population. Long winded? Maybe but still on the money. That, is the whole point. The types of change of life forms over time that we have come to know as evolution occurs within the lineage not the individual. Any means by which individuals can accomplish breeding, is valid. If this way does succeed in passing on the individual's genes then the requirement for survival, the legacy of that lineage's genes and associated traits, is fulfilled. Still, variation in what is present in descendants is part of the legacy the raw material of and for further evolutionary change. Environments do not remain the same indefinitely, the variations in very generation is what provides the chance for some of the different individuals to have more opportunity and reproductive success. The changes in the environment and the descendants may occur at different speeds. Environments are always dynamic but so are the changes in the individual as well as their descendants. The is an interaction between the genome and the environment of the individual. Science is learning more about epigenetics in this regard. Methylation of DNA plays a role in gene regulation and expression. The DNA in the individual remains the exact same code but the gene functions are changed. So, exact same genome... yet a very different phenotype. Not all of the variation in a population is a change which would be harmonious with the environmental changes. The deliterious ones would be selected out by nature. However, there is the remaining chance that some of the variations is adapted to the new conditions in a way that is better than remaining completely unchanged (and therefore having little or no chance at all in the new environment). You could say that over the long run, nature, time and chance have and continue to favor hedged bets. These changes in conditions are found to occur in many ways, One obviously vital one is genetically. In non sexually reproducing organisms as well as sexually reproducing ones. Sometimes the genetic changes occur very randomly and other times not so randomly. The advantage of variation is, though not always immediate, it can produce a means of covering if not the all bets, at least more of them. A quality that can provide better opportunity in the survival of individuals with variations. The variation can result in preserving or enhancing a suitability of the individual but it must fulfill the "survival requirement" mentioned earlier. One must be careful here, to not jump to the conclusion that there is always a progress or increasing complexity in the adapted variations. Suitability of a trait can also be the reversal of past trends. traits of the descendants don't have to be "modern", progressive or even of perfect design. There is only one criterion for Nature. It just has to work. Or at the least not get in the way for the purposes of survival. In fact so long as traits service the purpose, traits can even be very flexible.Traits can serve in one function and serve another function in different situations. Traits can serve multiple functions as well. Now as to fitness What is fit? Although an individual in good physical shape will likely have the qualities to manage better in the task of survival, i.e. dealing with the environment, competition for mates, disease, predators, or finding and obtaining food, this may not always be the only conditions leading to successful reproduction. Fit does not necessarily mean only the physical condition of the individual. We use fit in everyday language in more than only this way. If a particular shirt does not " fit " we are apt to mean that either it is not harmonious in some way with the rest of the ensemble or that it is the wrong size. Either way fit is taken to mean that it is suitable to the context, whatever that may turn out to be. Suitable to the context, is the same as saying fit the criteria. What this fitness really comes down is the qualities possessed by the individual which perhaps in varying degrees allows the individual to accommodate the circumstances in which it is in and accomplish reproduction in a way that continues the line. Another word for this suitability is "adapted". If an individual lacks sufficient suitability it almost certainly it will lead to fewer offspring and if the lack of suitability is also in the remaining offspring ...well. Taking this to the level of the population, is what extinction is. There is no conscience selection, the consequence is that those who have a greater contribution through descendants will eventually be what's around in the future. In case this still isn't clear, as an example, a rabbit, even in the best of shape, healthy, muscles all toned, bright and alert, still is not fit to live in the ocean. It's traits are not suitable to that context. The act of reproduction and its completion to a successful result would to put it mildly be hindered and any opportunities for the future of its lineage drastically limited. One need only look at the ubiquitous and dramatic natural changes such as floods or droughts to see that conditions do not remain the same forever. This example does even begin to take into consideration the infinitesimal small and gradual changes which are also occurring all the time. And, hey, physical environment is only one aspect of the total context of nature. Keeping this in mind isn't such a bad idea. It is not only one factor that can determine fitness, the whole is the context and even the slightest difference or change can have an important influence, especially if it is a trend which lasts over a long time. Survival is the successful differential reproduction of individuals inheritance into the future through descendants. Fit is the suitability and harmony of the individuals traits within the context or environment in which it exists that permits or in particular provides an advantage for this survival to occur. Overall the effects of these things on individuals are manifest in the population. Changes in life forms in populations are mediated by the individuals that compose the population. Changes in the individuals can lead to changes in reproduction between them. Major changes in the composition of the population is the how Speciation is recognized. The main determinant for a species is viable reproduction, any inherited modification blocking, or eventually blocking reproduction between individuals will likely lead to different species. This process of change is a factor in the origin of species. It is by keeping these definitions in mind that I hope you will have a different perspective of what descent with modification is all about and realize that...

The THEORY of EVOLUTION Proven by evidence, EVOLUTION is a FACT!

In order to keep this post short I have published a summary of  natural selection separately:
"Natural Selection: In A Nut Shell"

Science and Rigor

Have fun, play safe

MU-Peter Science

© 2016 MU - Peter Shimon