Darwin's Theory Of Evolution - The Premise

ЭССЕ

Ч.Дарвиннің эволюциялық теориясы

Чарлз Роберт Дарвин (1809-1882) - органикалық дүние эволюциясының негізін салған ағылшынының ұлы жаратылыстанушы ғалымы. "Бигль" кемесімен 5 жылға созылған саяхатта жинаған деректері - зерттеулерінің негізгі арқауы болды. Өзгергіштік, сұрыптау, тіршілік үшін күрес эволюцияның негізгі факторы екендігін және адамның төменгі сатыдағы жануарлардан шыққандығын дәлелдеді. Органикалық дүние эволюциясының себептері мен заңдылықтарын ашты. Еңбектері: "Табиғи сұрыпталу", "Түрлердің шығуы", "Үй жануарлары", "Адамның шағу тегі", "Жыныстық сұрыпталу", "Құрттар" және т.б. Жаратылыстанудың әр саласынан (геология, палеонтология, биогеография, эмбриология, салыстырмалы анатомия, цитология және т.б) жиналған материалдар "табиғат өзгермейді" деген көзқарасты жоққа шығарды. Ч.Дарвин іліміне "Бигль" кемесімен саяхат жасағанда жинаған экспедициялық материалдары да көп пайдасын тигізді.

Ч.Дарвин эволюциялық теорияны бірінші болып ашпағанымен эволюция- өзгерткіштік қатар жүруінен болатын құбылыс екендігін дәлелдеді. Ол тек табғаттың табиғи заңының әсерінен дамитынын түсіндіріп, эволюциялық процесті бірінші болып дәлелдеп берді

Ч. Дарвин органикалық дүниенің тарихи дамуы эволюцияның 3 факторына байланысты екендігін анықтады, олар: тұқым қуалайтын өзгергіштік, тіршілік үшін күрес және табиғи сұрыпталу.

Тұқым қуалайтын өзгергіштік, тіршілік үшін күрес және табиғи сұрыпталудың өзара байланысының нәтижесінде түрлер тіршілік ортасына бейімделіп, өзгеріп отырады. Міне, бұл – Дарвиннің эволюциялық теориясының негізгі қағидалары.

 

 

Darwin's Theory Of Evolution

Darwin's Theory Of Evolution - The Premise

Darwin's Theory of Evolution is the widely held notion that all life is related and has descended from a common ancestor: the birds and the bananas, the fishes and the flowers -- all related. Darwin's general theory presumes the development of life from non-life and stresses a purely naturalistic (undirected) "descent with modification". That is, complex creatures evolve from more simplistic ancestors naturally over time. In a nutshell, as random genetic mutations occur within an organism's genetic code, the beneficial mutations are preserved because they aid survival -- a process known as "natural selection." These beneficial mutations are passed on to the next generation. Over time, beneficial mutations accumulate and the result is an entirely different organism (not just a variation of the original, but an entirely different creature).

Darwin's Theory of Evolution - Natural Selection
While Darwin's Theory of Evolution is a relatively young archetype, the evolutionary worldview itself is as old as antiquity. Ancient Greek philosophers such as Anaximander postulated the development of life from non-life and the evolutionary descent of man from animal. Charles Darwin simply brought something new to the old philosophy -- a plausible mechanism called "natural selection." Natural selection acts to preserve and accumulate minor advantageous genetic mutations. Suppose a member of a species developed a functional advantage (it grew wings and learned to fly). Its offspring would inherit that advantage and pass it on to their offspring. The inferior (disadvantaged) members of the same species would gradually die out, leaving only the superior (advantaged) members of the species. Natural selection is the preservation of a functional advantage that enables a species to compete better in the wild. Natural selection is the naturalistic equivalent to domestic breeding. Over the centuries, human breeders have produced dramatic changes in domestic animal populations by selecting individuals to breed. Breeders eliminate undesirable traits gradually over time. Similarly, natural selection eliminates inferior species gradually over time.

The theory of evolution by natural selection, first formulated in Darwin's book "On the Origin of Species" in 1859, is the process by which organisms change over time as a result of changes in heritable physical or behavioral traits. Changes that allow an organism to better adapt to its environment will help it survive and have more offspring.

Evolution by natural selection is one of the best substantiated theories in the history of science, supported by evidence from a wide variety of scientific disciplines, including paleontology, geology, genetics and developmental biology.

The theory has two main points, said Brian Richmond, curator of human origins at the American Museum of Natural History in New York City. "All life on Earth is connected and related to each other," and this diversity of life is a product of "modifications of populations by natural selection, where some traits were favored in and environment over others," he said.

More simply put, the theory can be described as "descent with modification," said Briana Pobiner, an anthropologist and educator at the Smithsonian Institution National Museum of Natural History in Washington, D.C., who specializes in the study of human origins.

The theory is sometimes described as "survival of the fittest," but that can be misleading, Pobiner said. Here, "fitness" refers not to an organism's strength or athletic ability, but rather the ability to survive and reproduce.

Origin of whales

In the first edition of "The Origin of Species" in 1859, Charles Darwin speculated about how natural selection could cause a land mammal to turn into a whale. As a hypothetical example, Darwin used North American black bears, which were known to catch insects by swimming in the water with their mouths open:

"I can see no difficulty in a race of bears being rendered, by natural selection, more aquatic in their structure and habits, with larger and larger mouths, till a creature was produced as monstrous as a whale," he speculated.

The idea didn't go over very well with the public. Darwin was so embarrassed by the ridicule he received that the swimming-bear passage was removed from later editions of the book.

Scientists now know that Darwin had the right idea but the wrong animal: Instead of looking at bears, he should have instead been looking at cows and hippopotamuses.

The story of the origin of whales is one of evolution's most fascinating tales and one of the best examples scientists have of natural selection.

 

The last shore-dwelling ancestor of modern whales was Sinonyx, top left, a hyena-like animal. Over 60 million years, several transitional forms evolved: from top to bottom, Indohyus, Ambulocetus, Rodhocetus, Basilosaurus, Dorudon, and finally, the modern humpback whale.

Darwin's Theory of Evolution - Slowly But Surely...
Darwin's Theory of Evolution is a slow gradual process. Darwin wrote, "…Natural selection acts only by taking advantage of slight successive variations; she can never take a great and sudden leap, but must advance by short and sure, though slow steps." Thus, Darwin conceded that, "If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down." Such a complex organ would be known as an "irreducibly complex system". An irreducibly complex system is one composed of multiple parts, all of which are necessary for the system to function. If even one part is missing, the entire system will fail to function. Every individual part is integral. Thus, such a system could not have evolved slowly, piece by piece. The common mousetrap is an everyday non-biological example of irreducible complexity. It is composed of five basic parts: a catch (to hold the bait), a powerful spring, a thin rod called "the hammer," a holding bar to secure the hammer in place, and a platform to mount the trap. If any one of these parts is missing, the mechanism will not work. Each individual part is integral. The mousetrap is irreducibly complex.

Darwin's Theory of Evolution - A Theory In Crisis
Darwin's Theory of Evolution is a theory in crisis in light of the tremendous advances we've made in molecular biology, biochemistry and genetics over the past fifty years. We now know that there are in fact tens of thousands of irreducibly complex systems on the cellular level. Specified complexity pervades the microscopic biological world. Molecular biologist Michael Denton wrote, "Although the tiniest bacterial cells are incredibly small, weighing less than 10-12 grams, each is in effect a veritable micro-miniaturized factory containing thousands of exquisitely designed pieces of intricate molecular machinery, made up altogether of one hundred thousand million atoms, far more complicated than any machinery built by man and absolutely without parallel in the non-living world."

And we don't need a microscope to observe irreducible complexity. The eye, the ear and the heart are all examples of irreducible complexity, though they were not recognized as such in Darwin's day. Nevertheless, Darwin confessed, "To suppose that the eye with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I freely confess, absurd in the highest degree."

Modern understanding

Darwin didn't know anything about genetics, Pobiner said. "He observed the pattern of evolution, but he didn’t really know about the mechanism." That came later, with the discovery of how genes encode different biological or behavioral traits, and how genes are passed down from parents to offspring. The incorporation of genetics and Darwin's theory is known as "modern evolutionary synthesis."

The physical and behavioral changes that make natural selection possible happen at the level of DNA and genes. Such changes are called mutations. "Mutations are basically the raw material on which evolution acts," Pobiner said.

Mutations can be caused by random errors in DNA replication or repair, or by chemical or radiation damage. Most times, mutations are either harmful or neutral, but in rare instances, a mutation might prove beneficial to the organism. If so, it will become more prevalent in the next generation and spread throughout the population.

In this way, natural selection guides the evolutionary process, preserving and adding up the beneficial mutations and rejecting the bad ones. "Mutations are random, but selection for them is not random," Pobiner said.

But natural selection isn't the only mechanism by which organisms evolve, she said. For example, genes can be transferred from one population to another when organisms migrate or immigrate, a process known as gene flow. And the frequency of certain genes can also change at random, which is called genetic drift.

A wealth of evidence

Even though scientists could predict what early whales should look like, they lacked the fossil evidence to back up their claim. Creationists took this absence as proof that evolution didn't occur. They mocked the idea that there could have ever been such a thing as a walking whale. But since the early 1990s, that's exactly what scientists have been finding.

The critical piece of evidence came in 1994, when paleontologists found the fossilized remains of Ambulocetus natans, an animal whose name literally means "swimming-walking whale." Its forelimbs had fingers and small hooves but its hind feet were enormous given its size. It was clearly adapted for swimming, but it was also capable of moving clumsily on land, much like a seal.

When it swam, the ancient creature moved like an otter, pushing back with its hind feet and undulating its spine and tail.

Modern whales propel themselves through the water with powerful beats of their horizontal tail flukes, but Ambulocetus still had a whip-like tail and had to use its legs to provide most of the propulsive force needed to move through water.

In recent years, more and more of these transitional species, or "missing links," have been discovered, lending further support to Darwin's theory, Richmond said.

Controversy

Despite the wealth of evidence from the fossil record, genetics and other fields of science, some people still question its validity. Some politicians and religious leaders denounce the theory, invoking a higher being as a designer to explain the complex world of living things, especially humans.

School boards debate whether the theory of evolution should be taught alongside other ideas, such as intelligent design or creationism.

Mainstream scientists see no controversy. "A lot of people have deep religious beliefs and also accept evolution," Pobiner said, adding, "there can be real reconciliation."

Evolution is well supported by many examples of changes in various species leading to the diversity of life seen today. "If someone could really demonstrate a better explanation than evolution and natural selection, [that person] would be the new Darwin," Richmond said.

 

 

Footnotes:

Charles Darwin, "On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life," 1859, p. 162.

Ibid. p. 158.

Michael Behe, "Darwin's Black Box," 1996.

"Unlocking the Mystery of Life," documentary by Illustra Media, 2002.

Michael Denton, "Evolution: A Theory in Crisis," 1986, p. 250.

Charles Darwin, "On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life," 1859, p. 155.

 

 

1.Теннис ойыны:
Сандар сөйлейді:
•..... жылы Дарвин өзінің негізгі шығармасын - «Табиғи сұрыпталу арқылы өмірдің пайда болуы» жарыққа шығарады.
• Антропологиялық проблемаларға тікелей қатысы бар Дарвиннің екі шығармасы бар. Олар:
• «Адамның шығу тегі және жыныстық тандау» (...... ж.)
• «Адам мен жануарлардын мінез–құлықтары» (....... ж.). Осы жұмыстар Ч.Дарвиннің жалпы теориясын адамның шығу тегі проблемаларын шешуде қолдануды ұсынады. Дарвиннің теориясында «адам маймылдан шықты» деп тұжырымдады.

Тест

1.Алғашқы эволюционист

А) Ж.Б.Ламарк В)И.Дарвин С)К.Линней

2.Жаңа қолтұқымдар, іріктемелер жасайтын шығармашылық үрдіс.

А) әдістемелік В) санасыз С) табиғи

3.Тұқым қуаламайтын өзгергіштік:

А) Жеке В) Топтық С)Модификациялық 4.Эволюцияның атасы

А) Ж.Б.Ламарк В)И.Дарвин С)К.Линней

5.Малдың еттілігін,сүттілігін арттыру

А)Табиғи сұрыпталу В)Қолдан сұрыптау С)Санасыз сұрыптау

3. Биологиялық диктант
1. Ч. Дарвиннің 1859 жылы жарық көрген еңбегі
………………………………………………………………….. деп аталады.
2. Ч. Дарвиннің 1868 жылы жарыққа шыққан еңбегі ……………………………………………………………………. деп аталады.
3. Ч. Дарвиннің 1871 жылы жарыққа шыққан еңбегі ………………………………………………………………………. деп аталады.
4. Адасқан сөздер:

1. ЯКИЕСЕЛЦ 2. ВЭОЦЯИЛЮ

3. РАДЦЯИГА 4. НЙНЛЕИ

5. КРМАЛА 6. ВРДНАИ

Бақылау сұрақтары.

1.ХІХ-ғасырдың І-ші жартысында Англияда жүзеге асқан қоғамдық-экономикалық өзгерістер.
2.ХІХ- ғасырдың І-ші жартысында жаратылыстану ғылымдарының даму дәрежесі (систематика, салыстырмалы анатомия, эмбриология).
3.ХІХ- ғасырдың І-ші жартысында ауыл шаруашылық практикасының даму дәрежесі.4.Ч.Дарвиннің өмірбаяны және еңбектері.?
5. “Түрлердің шығу тегі” еңбегіндегі негізгі қағидалар?
6.Мәдени формалардың эволюциясын дәлелдеу?