in his book “Role of labor in the process of turning ape into humans.”
(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
Savannah’s. 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.
“Organisms 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 heritable—that 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.”
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 “Contributions to the theory of
Natural Selection” to demonstrate natural selection.
“The Duke of Argyll, in his “Reigh of Law,” 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: --“The 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.”
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?
“The 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.” (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 change—natural 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) “continued 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 strains”
Bibliography
1) “Long Argument,” Ernest Mayr, Harvard University Press, 1991.
2) “Darwinism defended,” Michael Ruse, Addison-Wesley Publishing Company,
1982.
3) “The Descent of Man and Selection in Relation to Sex,” Charles Darwin,
1974.
4) “Wonderful Life,” Stephen Jay Gould, W.W. Norton & Company, 1989.
5) “Contributions to the theory of natural selection,” Wallace, Alfred
Russel, AMS Press, 1973.
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[1] Teaching about Evolution
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A. afarensis
A. africanus
H. habilis
A. robustus
H. erectus
H. sapiens
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