–ефераты. Impact of Evolution on Human Thought. Evolution






Impact of Evolution on Human Thought. Evolution

Farid Gazizov

Impact of Evolution on Human Thought

Evolution

Evolution by definition of Webster dictionary is a gradual development

of simple matters into more complex. When most of the people hear

УevolutionФ it associates with development or history of the earth.

History of the earth compiles of gazillions of steps. The very first step

in our history is a birth of the earth, which took place over 4 billion

years ago.

УPowerful telescopes reveal new stars coalescing from galactic dust,

just as our sun did more than 4.5 billion years ago. The earth

itself formed shortly thereafter, when rock, dust, and gas circling

the sun condensed into the planets of our solar system. Fossils of

primitive microorganisms show that life had emerged on earth by

about 3.8 billion years ago (Teaching about evolution and the

Natural of Science, ch. 1).Ф

Many people throughout the centuries have been trying to find

explanations to the questions like: Why are surrounding us things the way

they are?; why some type of animals resemble another one? It was hard to

answer these questions without proper tools, experience and background

knowledge. Even nowadays, not all questions are answered. Darwin was the

first human who succeeded in responding to these questions. He was the

first one who put discovered facts and knowledge available by his time in

one big picture. In attempts to explain the history Darwin created the

most outstanding achievement of human beings that had enormous impact of

our thinkingЧevolutionary thinking. Ernest Mayer, in his book УOne Long

ArgumentФ says following about impact of DarwinТs work on human thinking.

УIt is almost impossible for a modern person to project back to the

early half of the nineteenth century and reconstruct the thinking of

this pre-Darwinian period, so great has been the impact of Darwinism

on our views (E. Mayr, pp. 1)

For our further discussion, one should explicitly distinguish between

evolution and evolutionary theory. Evolution (history) is a serious of

facts that occurred since the birth of the earth, while evolutionary theory

is the best way available nowadays to explain why evolution happened the

way it happened, but not otherwise. Both evolution and evolutionary theory

make series of claims. Some of them are secondary and some are primary.

Primary claims if proved wrong, would change entire theory.

Primary Claims of Evolution

The earth is over 4 billion years old. In the past when technology was

not very developed it was hard to prove age of the earth. Scientists had

been aging by measuring the rate of sedimentation. Another method of

defining age, which was used in 1800s, is noticing what kinds of fossil

rocks have. Currently it is done by chemical analysis of composition of

fossil.

УSome elements such as uranium, undergo radioactive decay to produce

to produce other elements. By measuring the quantities of

radioactive elements and elements into which they decay in rocks,

geologists can determine how much time has elapsed since the rock

cooled from initially molten state (Teaching About Evolution and the

Nature of Science).Ф

Life on the earth did not appear right after appearance of the earth.

The first sings of life were dated about 550 million years ago according

to the oldest fossils. This fact does not specifically mean that where was

not life forms before that time. Life forms were very simple and lacked

hard parts like bones or shells and could rarely preserve in the fossils.

УHowever, a few pre-Cambrian organisms left traces of their existence.

Some ancient rocks contain stromatolitiesЧthe remnants of bacteria

that grew in columns like stacked pancakes (Teaching About Evolution,

ch. 3, pp. 2)

Extinction is a major feature of biological evolution. It is in a

tight connection with natural selection. Natural selection works only by

means of surviving of changes, in some sense useful, and therefore,

striking root. In the consequence, fast increase of the numbers of all

organic matters in geometrical progression, every natural habitat already

filed to the limits by its habitants. From this it follows those more

adapted forms will increase in numbers and less adapted, will decrease in

numbers and become rare. Rarity of the form is a predecessor of the

extinction. Every form represented by small numbers of individuals has big

chances for a complete extinction in consequence of significant climatic

swings within a year or in consequence of temporary increase of enemies.

Species, most abundant of individuals, have the biggest chances for

appearance at any particular time of favorable changes. Rare individuals

will at any particular time change and perfect at a slower pace and in

consequence of that will be defeated in a life struggle with changed and

improved descendants of more common individuals. From this it follows that

since with a passage of time natural selection УcreatesФ new species, than

other species become more rare, and finally extinct.

For example, during laying eggs season, sea turtles hay hundreds of

thousands eggs. While hatching and getting to the ocean most of the

generation becomes easy pray of sea birds. Since just hatched turtles do

not have a hard cover that could protect them, many of them dye in the

ocean. By maturity time only about one out of thousand turtles stay alive.

Currently there are billions of living organisms that inhabit the earth,

but they represent only around one percent of all living organisms that

have ever lived on the earth since its birth. Ninety nine percent dyed

out.[1]

Another example that mechanisms of evolutionary change are

observable and verifiable is the one described by Henry Walter Bates.

УIn 1862, Henry Walter Bates made brilliant use of the

Darwinian mechanism of natural selection asking why it is that some

species of butterfly very closely mimic species of butterfly,

essentially quite different, Bates proved beyond doubt that the answer

lies in adaptive advantage brought about by natural selection. The

mimicked insects are highly distasteful to birds who think that they

belong to distasteful species. Bates showed experimentally that birds

learn to avoid distasteful insects, and that the closer the mimic, the

less change there is that the insect will be eaten.Ф

Secondary Claims of Evolution

When the earth appeared for the first time it was very different from

its current conditions. The surface of the earth was represented by bare

bedrock. At the time of its birth, the earth represented cold matter,

close by its composition to meteorites. Material it was mad of, contained

radioactive elements. In consequence of the heat excretion while

radioactive decomposition of the core and gravitational compression.

However, because of continuous loss of heat through he surface and lack of

radiation heat complete melting of the earth did not happen. In result of

earthТs melting, water and different gases were brought up to the surface.

This water began formation of hydrosphere.

Location of continents and oceans were very different. According to

WegenerТs hypothesize, which he later supported by evidence, earthТs

continents used to be a single land, which was called Pangea. About two

hundred million years ago Africa and South America slowly began their

movement toward their current location. Wegener supported his hypothesize

by geological and biological evidence. At the place where the continents

were aligned, were found fossilized animals and plants dated more than two

hundred million years old. Besides, if Africa and South America had always

been separate continents as they are now, both of them would have had very

different flora and fauna, which are not.

Starting at 1950 up to 1970 evidence begin exposing to the world that

support hypothesis of continentТs slow movement. Sonar mapping of the

ocean floor showed winding, continuous ridges system around the planet.

The ridges appeared where molten matter was coming up from the earthТs

inside.

Not only topography of the earth has changed, but composition

atmosphere has changed as well. Current atmosphere contains a lot of

oxygen, which is result of existence of life. During photosynthesis, green

plants consume water and dioxide and release oxygen in atmosphere. This is

considered to be a secondary claim because even if the earth would not

developed as it considered, it would have no impact on evolutionary theory.

Origin of human being was an interest of human more than origin of

plant and animals. Attempt to understand and explain origin of humans is

expressed in religions, legends of all kind of trails and folks. For a

long period of time science knowledge were abrupt and incomplete in order

to solve a problem of human origin. Only in 1857 Darwin expressed

hypothesis, and in 1871 in his book УThe Origin of man and relation to

sex,Ф convincelly proved that humans originate from pre-existing humanlike,

but were not created by intelligent designer. Role of social factors,

which was pointed out by Darwin, was detailly described by Fredrik Engels

in his book УRole of labor in the process of turning ape into humans.Ф

(1896)

Human and vertebrates commonness is strongly supported by similar

arrangement of internal organs: skeleton, nerve system, blood system,

respiration, and digestion.

Rudiments and atavisms are very important evidences of human

relatedness to animals. There are about 90 rudiments in human body: coccyx

bone (remaining of the reduced tail); folds in the corner of the eyes

(remaining of the blinking tympanum; thin body hair (remaining of the

hair). All these rudiments are inherited from an animal ancestor. An

external tail, which sometimes people are born with, is related to

atavisms. Another atavism is abandon hair on the face and body.

Common details of the body arrangement are evidence of close

relativeness of human and anthropoids: wrist with flat nails, shape of eyes

and years, the same number of canine and molar teeth, complete change of

baby teeth, and so forth. Physiological commonness is very important: the

same blood groups, diseases (tuberculosis, fly, smallpox, cholera, AIDS,

pneumonia) and parasites (louse). Besides numerous common features, there

is a number of explicit differences evidencing that its current stage,

human is considered to be different species. Only human has ability of

upright walking and related to that peculiarity of structure of the S-

shaped backbone with explicit neck and lumber bend, low extended pelvis,

and etc. Human skull is higher and more rounded without superciliary arch;

brain part of skull is in most part dominated by facial; high forehead,

weak jaws with small canine. Human brain is about two and half times

bigger than one of humanlike apes, and 3-4 times heavier.

Human being evolved from other pre-existing species. Even in ancient

times it has been noticed that humans have a lot of in common with a other

animals just like other animals human had the same internal organs (heart,

lungs, liver etc.). Ancient Greeks had a scale of living organisms known

by their time. Human being was placed at the end of the scale. Below were

higher animals like houses, sheep and so forth, but it is hard to believe

that humans were next step in the biological evolution of living organisms

right after higher animals. Only by the eighteenth century ape-like being

became known to Europe. This discover shed light on a huge gap between

higher animal and humans (Darwinism defended, Ruse, pp. 230). After that

some scientists (for example Huxley) assumed that humans descended from

apes. Later, having examined all differences between apes and humans,

Huxley came to conclusion that humans and apes descended from a common

ancestor. One would probably ask why our common ancestor did split into

two branches, apes and Australopithecus afarensis (which is considered to

be an ancestor of all hominids). There is a scientific explanation, which

relates to climatic changes in Africa. Our ancestor was used to live in

the area of heavy precipitation. With a passage of time climate started

turning into dry one and forestlands began retreating, leaving behind

SavannahТs. Some species stayed in dwindling forests. Others (our

ancestors) started advancing toward opened spaces.

With a change of place of inhabitation, there were some changes in

diet of our ancestor. Anthropologists suggested that tooth reduction took

place because our ancestor started to use grass seeds and the like as a

food source (Darwinism Defended).

Major Claims of Evolutionary Theory

Natural selection is the major moving factor of the evolution of the

living organisms. Almost at the same time, several English naturalists

arrived at the idea of existence of natural selection (P. Mathew (1831), A.

Blight (1935), A. Wallace (1858), C. Darwin (1858)), but only Darwin

succeeded in exposing of the meaning of this phenomenon as the major factor

of evolution and created the theory of natural selection. On the contrary,

to artificial selection held by humans, natural selection is conditioned by

influence of surrounding environment upon the organisms. According to

Darwin natural selection is survival of the most accommodated organisms, in

consequence of which, on the basis of undefined inherited changeableness in

the series of generations evolution occurs.

In process of natural selection species more accommodated to

surrounding environment survive, those who do are not, go extinct.

Explicit example of that is our ancestors that had advantage of standing

upright to look out and look for possible object of prey. Natural

selection does not specifically have to lead to perfection. It leads only

to surviving of species that can survive. If entire kind of particular

animals can not survive in changed environment, entire kind will dye out.

УOrganisms in nature topically produce more offspring that can survive

and reproduce given the constraints of food, space, and other

resources in the environment. These offspring often differ from one

another in ways that are heritableЧthat is, they can pass on the

differences genetically to their own offspring. If competing

offspring have traits that are advantageous in a given environment,

they will survive and pass on those traits. As differences continue

to accumulate over generations, populations of organisms diverge from

their ancestors.Ф

Process of natural selection consists of two steps: the first one is

reproduction of genetically different species; the second step is surviving

of the most adopted individuals in surrounding environment. An example can

be nest of birds in which some nestlings have a little bit different

coloring than others. If this coloring better matches the tree these birds

in habit, this will give them advantage of better hiding from predators,

which leads to increase in changes of reproduction. Below are example that

Wallace, Alfred Russle uses in his book УContributions to the theory of

Natural SelectionФ to demonstrate natural selection.

УThe Duke of Argyll, in his УReigh of Law,Ф has pointed out the

admirable adaptation of the colors of the woodcock to its protection.

The various browns and yellows and pale ash-color that occur in fallen

leaves are all reproduced in its plumage, so that when according to

its habit it rests upon the ground under trees, it is almost

impossible to detect it. In snipes the colors are modified so as to

be equally in harmony with the prevalent forms and colors of marshy

vegetation. Mr. J.M.Lester, in a paper read before the Rugby School

Natural History Society, observes: --УThe wood-dove, when perched

amongst the branches of its favorite fir, is scarcely discernible;

whereas, were it among some lighter foliage, the blue and purple tints

in its plumage would far sooner betray it. The robin redbreast too,

although it might be thought that on its breast made it much easier to

be seen, is in reality not at all endangered by it, since it generally

contributes to get among some russet or yellow fading leaves, where

the red matches very well with the autumn tints, and the brown of the

rest of the body with the bare branches.Ф

Core of natural selection is variation within the kind. If variation

does not exist either entire kind will survive and stay unchanged or it

will go extinct. But what it a source of variation? The ultimate source of

variation is mutations in genes. If new traits gained through mutation

leads to successful survival and reproduction than new traits will be

inherited and spread within the population. Mutation is random, but

natural selection is not.

All living organisms that currently inhabit the earth share common

ancestry. Through the history by means of natural selection and variation

first, simple forms of life were evolving into different, more complex

forms. How to prove it?

УThe discovery of the structure of DNA by Francis Crick and James

Watson in 1953 extended the study of evolution to most fundamental

level the sequence of the chemical basis in DNA both specifies the

order of amino acids in proteins and determines which proteins are

source of both change and continuity in evolution. The modification

of DNA through occasional changes or rearrangements in the base

sequences underlies the emergence of new traits, and thus of new

species, in evolution. At the same time, all organisms use the same

molecular codes to translate DNA base sequences into Protein amino

acid sequences. This uniformity in genetic code is power evidence for

the interrelatedness of living things.Ф (Teaching About Evolution and

the Nature of Science, ch. 2, pp. 4)

Another powerful argument that supports common ancestry is a fact

that man is developed from an ovule, about the 125th of an inch in

diameter, which does not differ from the ovules of other animals. At a

very early period, the embryo can hardly be distinguished from another

member of vertebrate kind.

In order to convince one that evolution happened the way evolutionary

theory describes it evidences must be presented. Major evidence and

argument of evolutionary theory is that all of the mechanisms of

evolutionary theory change are currently observable. Let us take for

example main mechanism of evolutionary changeЧnatural selection. Nowadays

our society is facing serious public health problem. Bacteria that

medicine used to successfully fight with antibiotics is becoming more

resistant to one. This means that week bacteria go extinct and only strong

(more resistant to antibiotics) bacteria survived. (Teaching about

evolution, ch. 2, pp. 5) Уcontinued use and overuse of antibiotics has had

the effect of selecting for resistant population because the antibiotics

give these strains and advantage over non-resistant strainsФ

Bibliography

1) УLong Argument,Ф Ernest Mayr, Harvard University Press, 1991.

2) УDarwinism defended,Ф Michael Ruse, Addison-Wesley Publishing Company,

1982.

3) УThe Descent of Man and Selection in Relation to Sex,Ф Charles Darwin,

1974.

4) УWonderful Life,Ф Stephen Jay Gould, W.W. Norton & Company, 1989.

5) УContributions to the theory of natural selection,Ф Wallace, Alfred

Russel, AMS Press, 1973.

-----------------------

[1] Teaching about Evolution

-----------------------

A. afarensis

A. africanus

H. habilis

A. robustus

H. erectus

H. sapiens



2012 © ¬се права защищены
ѕри использовании материалов активна€ ссылка на источник об€зательна.