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Evidence of the theory of evolution essay

When I was a boy at a Roman Catholic school in the early 1960s, I had to learn the Catechism and essentially this offered a three-word answer to the question which was: I soon came to believe that this answer was as wrong as it was inadequate. Consequently there are very few brief, accurate and intelligible pieces of writing on the origins of humankind.

This essay attempts to address that gap. Before setting out the evidence for evolution and considering some of the arguments advanced against it, it would be as well to have a clear understanding of what is meant by the biological term 'evolution'. The theory of evolution was independently developed by Alfred Russel Wallace and Charles Darwin, but it was the latter who first set out the case in book form in his "On The Origin of Species" which was first published in 1859.

In that book, humans were barely mentioned. It was only in "The Descent Of Man" published in 1871 that he spelled out how humankind too was the subject of evolution and shared an ancestor with the chimpanzee. Evolution therefore is an explanation for the origin of all life forms or species: It holds that all life forms have the same origin and that one form of life evolves into another through a process known as natural selection.

How does this work? All life forms comprise cells which undergo a process of division. Most mutations are neutral or disadvantageous rather than potentially beneficial, if only because they are random and there are many more ways of becoming worse than of becoming better. Nature selects for preference those random mutations which confer on that life form a greater chance of survival and reproduction.

Where one population is isolated from another that is, they cannot interbreedspecies can and do develop different characteristics reflecting the local circumstances in terms of geography, climate, prey, predators and food supply.

The process has been dubbed 'the survival of the fittest' although this was not a term which originated with Darwin himself. Although Darwin evidence of the theory of evolution essay did not know this, the biological means by which these mutations conferring advantage are passed from one generation to another is particular genes in a gene pool.

A gene is a length of DNA which is deoxribonucleic acid that contains the genetic instructions used in the development and functioning of virtually all known living organisms. The process of natural selection is incredibly slow in terms of human life spans, but there has been plenty evidence of the theory of evolution essay time for natural selection to work, since the Earth is around 4.

So, in the natural world as opposed to a breeding centre or a laboratorychanges - such as a longer neck or a faster speed or a larger brain - take a long time to evolve, so long that one cannot identify the point at which one species actually becomes another.

  1. We do not have an explanation for the start of evolution It is true that we have no evidence about what actually started the long process of evolution, although there are a variety of hypotheses for what is known technically as abiogenesis, most notably the iron-sulphur world theory metabolism without genetics and the RNA world hypothesis RNA life-forms. The evidence for evolution.
  2. But, for instance, our diet differs from our ancestors and our teeth now do not need to be so strong, but any dental problems can now be addressed by dental care which somewhat 'interferes' with unconstrained evolution. The period concerned was about 20 million years which seems large but occurred half a billion years ago.
  3. Nature selects for preference those random mutations which confer on that life form a greater chance of survival and reproduction. However, since Darwin first enunciated his thesis, palaeontologists have discovered many intermediate forms between different groups of animals.

Natural selection can appear wasteful and cruel. Most species have not survived various mass extinctions. The most famous is the Cretaceous-Tertiary extinction of some 65 million years ago which resulted in the death of the dinosaurs. Today, as throughout evolution, most animals die young and painfully either through starvation or predation. It really is a brutal competition for survival with the fittest most likely to survive and pass its genes on to the next generation.

But it is vital to appreciate that this is not a plan or a design. It is an automatic process of natural selection by random mutation.

If there were no such process at work, we would not be here to consider it. Evolution explains the similarity of species Like any good scientific theory or law, evolution explains all the known facts in a consistent and convincing manner.

Most especially, it explains convincingly how present day species are related to each other. It explains why the DNA code is invariant across all living creatures while individual genes vary. Evolution explains the geographical distribution of species Evolution explains why animals tend to live on the same continent as fossils that are probably their ancestors and why evidence of the theory of evolution essay share the same continent with species that resemble them.

Conversely, no frogs are found on oceanic islands because frogspawn is immediately killed by sea water. Evolution suggests that such locations would have few species because of the difficulty of crossing the ocean and that such places would have animal forms that are found nowhere else because the habitat is so distinct. This is exactly what we find: Natural selection is analogous with other forms of selection We are reinforced in our view that over time random mutations can through natural selection result in different types of life and different versions of animals because we observe that artificial selection - for instance, of cabbages, roses, pigeons, dogs and horses - and sexual selection - for instance between peahens and peacocks - does the same on a much shorter timescale.

Evolution is confirmed by scientific dating methods We know that life has evolved over millions and millions of years and not a few thousand years because of scientific dating techniques such as the decay of radioactive materials and carbon dating.

All these dating techniques not only reveal a very long process of evolution but are remarkably consistent in the dates that they offer us. Evolution is confirmed by observation and experimentation The most striking case is the ever-increasing resistance of bacteria to anti-biotics. Bacteria multiply fast and are present in enormous numbers so that mutations that are resistant to a evidence of the theory of evolution essay anti-biotic can occur easily.

The more we use anti-biotics, the faster bacteria can evolve to be resistant to them. Another example is the increased frequency of tuskless elephants because of the killing of elephants for their ivory. The explanation is that the elephants that were not killed for their tusks were more likely to survive and became a growing band proportionally while their offspring with genes that did not produce tusks also had a better chance of survival.

In 2008, scientists found that the descendants of the transported lizards had significantly larger heads because they were eating more plant material. This was natural selection at work over a mere 37 years. The results were entirely consistent with the principles of natural selection through random mutation. Evolution is confirmed by the fossil record Very few fossils had been discovered at the time of Darwin's original thesis, but it was clear from the theory that, if evolution is true, fossils of simpler forms of life should be found at earlier or lower levels of strata of the Earth and fossils of more developed forms of life should be discovered in later or higher levels of strata.

This is exactly what the fossil record reveals. All fossils which have been found - and there are now very many - are in the correct temporal sequence. No fossil has ever been found in the 'wrong' sequence. Specifically we now have a rich supply of intermediate fossils linking modern humans with the common ancestor that humans share with chimpanzees. You can view for yourself a selection of such fossils in most museums of natural history.

Of course, the fossil record is not complete and never could be especially for animals which are not susceptible to being fossilised, but the fossil evidence in many major animal groups is strong and becoming ever stronger.

Evolution is confirmed by the gene pool Darwin did not know about genes which were first suggested by the Austrian scientist Gregor Mendel, although Mendel himself did not use the term which was only coined in 1909. A gene is a length of DNA that contains the genetic instructions used in the development and functioning of all living organisms. As the science of genetics has rapidly developed, we have become capable of mapping the genetic code of different life forms and identifying the incredible similarity in genetic composition of life forms which have common ancestors as explained by evolution.

It does not refer to the number of whole genes but to the number of DNA 'letters' that match each other. The point is that shared DNA is confirmation of shared ancestry as set out in the theory of evolution. There is an absence of design If emergence of life was not the result of a process of natural selection through random mutation, then it might be that it was the result of a non-random process involving design which would suggest a designer God. In fact, it is clear that there is no design.

On the contrary, there many instances of imperfection.

Darwin and His Theory of Evolution

A wonderful case occurs with the pouch of the koala bear which opens downwards instead of upwards as in a kangaroo, even though the koala spends its time hanging upright from trees.

The explanation - provided by evolution - is that the koala is descended from a wombat-like ancestor who flung soil backwards, necessitating a pouch facing downwards. The most dramatic illustration that life was not designed by a beneficent God is that of the ichneumon wasp which paralyses a caterpillar and then lays eggs inside its body which hatch to produce young which proceed to devour the caterpillar alive one organ after another in an order which keeps the caterpillar alive and therefore fresh as long as possible.

A classic example of imperfection is what is called the recurrent laryngeal nerve which takes a bizarre route from the brain to the larynx in mammals and humans.

Another example is the odd detour taken by the vas deferens - the pipe that carries sperm from the testis to the penis - in male humans. A third example is found in the sinuses of humans which has its drainage hole in the top rather than the bottom, a consequence of our shift from being quadruped to biped. Yet another example occurs in the eye - often represented by creationists as a marvel of design - where the retina is back to front, a defect that has to be corrected by the brain.

Public’s Views on Human Evolution

In fact, the human body abounds with imperfections which can only be explained by the long process of gradual evolution and modification. One more piece of evidence against any notion of design: Why is it there?

There are currently two possible explanations. The first view is that it must have coded for proteins no longer used by the descendant of the entity that did have use for that protein. If this is the case, it is not a good design. All these redundant genes in every cell take energy to create. The other view scientists are considering is that this redundant DNA may have something to do with the structural integrity of the DNA helix.

But again it is not an elegant design for a structural solution and was probably the result of the DNA's long evolution to the stable structure it eventually formed utilising the redundant DNA for structural purposes. Proteins form complex structures using ionic bonds electrical repulsion and attraction.

So nature can be beautifully simple and unnecessarily complex - but that is evolution not intelligent design. Over and above the routine imperfections to be found in the natural world, the absence of design at least by a rational and beneficient God is evident evidence of the theory of evolution essay the vast wastefulness and immense cruelty of nature. Most animals die early, without even having the opportunity to create offspring, and they frequently die cruelly, eaten alive or torn apart by another animal, or die slowly, wasted by disease or starvation.

Not a sensible or kind design or indeed any design. Evolution is a falsifiable theory Like any good scientific theory or law, evolution is falsifiable by contradictory evidence.

There has been no such contradictory evidence. If one fossil was found in strata representing a period older or younger than one would expect to find it, then the theory would be massively challenged. This has never happened. There is a missing link in the tree of life There is no missing link. Since evolution is continuous and its speed varies enormously, in a strict sense all species are in transition and it is often difficult to identify categorically when a transition occurs from one species to another.

However, since Darwin first enunciated his thesis, palaeontologists have discovered many intermediate forms between different groups of animals: The fossil Archaeopteryx is one of the most famous, discovered in 1861, a mere two years after the first publication of "On The Origin Of Species". It had feathers like a bird, but teeth, claws and a bony tail like a dinaosaur.

Ambulocetus, discovered in 1992, is known as the walking whale. It could walk on four legs on land and in water and heard by picking up vibrations through its jawbone like modern whales. Tiktaalik, discovered in 2004, is the link between fish and amphibian.

It looked like a primative fish crossed with early four-legged animals and had lungs and gills plus fins that could support much of its weight [for more information click here ]. Of course, from the perspective of a strict creationist who is determined to oppose and misunderstand evolution, each new intermediate form simply creates an extra missing link.

The point is that the tree of life is not a series of distinct links but a very gradual morphing from one form to another. There are no fossils for intermediate animals such as a fronkey Of course not, because monkeys are not descended from frogs.

  • The second factor, Darwin argued, is that although variations are random, some of them convey distinct advantages — superior camouflage, a heartier constitution or greater speed, for example — that better equip a creature to survive in its environment;
  • However, since Darwin first enunciated his thesis, palaeontologists have discovered many intermediate forms between different groups of animals;
  • The explanation - provided by evolution - is that the koala is descended from a wombat-like ancestor who flung soil backwards, necessitating a pouch facing downwards.

Equally humans are not descended from chimpanzees.