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Evolution theories - From ancient Greeks to modern Darwinism

summary: Theories of evolution.
Man has always raised questions about the world around him. We know that he has not
always looked like the one we know today (cfr. Dinosaurs ...). So we issued various
hypotheses that can neither deny nor confirm. Modern science is trying to establish an
explanatory theory of this development:
Plato (427-347 BC): Idealism or essentialism.
There are two worlds: a real world, perfect, eternal and an illusory world of
imperfection that humans perceive with their senses.
Organizations are ideal and perfectly adapted to their environment.
He denies the evolution that is unfavorable in a world populated by beings ideals
(perfectly adapted to their environment).
Aristotle (384-322 BC): The creationism.
It was a painstaking naturalist who believed that species were fixed and permanent and
they appeared spontaneously out of nothing or things that are completely foreign to
Species are permanent and perfect.
That said, concept of evolutionism as accurate descriptions of animals (whales =
mammal, different bat a bird ...). Aristotle criticized the Platonic dualism.
LUCRECE (98-55 BC): First idea of a natural selection.
LINNEUS (1707-1778): Taxonomy and binomial nomenclature (fixist).
"There are as many different species as the Infinite Being created in different forms
in the beginning".
In the 17th century, the invention of the microscope and the proliferation of travel
allowed scientist to explore a new area of unsuspected wealth.
This doctor and Swedish botanist published "Systema Naturae majorem ad Dei gloriam"
where species are grouped into categories based on the differences and similarities.
He was convinced, like his contemporaries, that the Creator had designed each species
to specific purposes and scientists are working to discover the Creator's plan.
No progressive parenting, species are created permanently.
Its ranking system will become an argument for the evolution of Darwin a century later.
Buffon (1707-1788): Transformism.
species derived from each other => common ancestor ... ????
Lamarck (1744-1829): First theory of the evolution of species published in 1809.
Gradual modification of a species through adaptations to the environment.
2 Laws:
Law of use and disuse:
Use: Frequent use and supported organ develops gradually organ.
Non-use: The non-use of an organ, the deteriorating to make disappear gradually.
The law of inheritance of acquired characteristics:
The developed organ / deterioration of an animal during its existence
will be transmitted to offspring.
Typical example: Giraffe grabs a long neck by dint of eating the leaves
located in the tree (use). This feature is acquired transmit to offspring
He was unable to prove the inheritance of acquired characteristics by experience. As a
result, many scientists are Darwinists.
That said, Lamarck was the inventor of evolutionism.
The organism is active in its transformation while for Darwin, the organism is passive.Georges CUVIER (1769-1832): Catastrophism.
His ideas in opposition to those of Lamarck, species are fixed, they do not turn. He
believes in creationism. The species have disappeared over time due to disasters
(catastrophism), which may explain in his mind the fossil remains of extinct species.
The regions are then re-colonized by other species from other places and that will not
change until they disappear. No evolution.
The current wildlife does not match the survivors.
That said, it adds a certain nuance in terms of "re-creations" successive.
Charles Darwin (1809-1889): Darwinism.
English naturalist, he enlisted at age 22 on the HMS Beagle, the ship which was, for 5
years, traveling the world, and especially the southern hemisphere where life is
abundant and diverse. It was for him the opportunity to observe very different life
forms from those he knew in his native England.
This is no doubt thanks to his observations he issued a non-theological theory (the final
result cannot be predetermined) he founded the unity and the diversity of life on the
evolution and explains it by selecting natural.
The main points of his theory (he hesitated to publish because it was better to build
compelling scientific evidence):
The species varies: the young are never completely identical to their parents or
identical to their parents or identical to each other
Living beings struggling to live; there is a competition between individuals that
they belong to the same species or more. This competition is most often caused
by an unbalanced diet affecting natural populations that suffer huge losses. This
is the selection that is responsible for the differentiation of species and
The differences, however small, can be favorable or unfavorable. Only reach
adulthood and reproduce those with advantageous characters to their
An animal that would have a genetic defect that would allow him to have more
chances of survival (eg more hair than others in a cold environment) than the
others, will be transmitted to offspring, "positive anomaly"
Darwin's theory:
1. Species of organisms inhabiting the Earth are descended from ancestral species.
2. Evolution is affected by natural selection and adaptation.
Example of natural selection:
The giraffes were lucky to be born with longer necks persist.
The darker butterflies living in a forest where the tree trunks are dark persist.
This is explained by the fact that they disguise themselves better than clearer.
The synthetic theory most accepted today considers paleontology, taxonomy,
biogeography and population genetics.
It reflects the gradualism that major changes resulting from the accumulation of
barely perceptible changes but spread out over long periods.
Study the classification of living things, taxonomy, today reviewed. The form is based
morphological classification Was Similarities while the new is based on the cladistic and
phylogenetic analysis or science branches (Establishing kinship entre species by
searching for shared advanced characters, minimum Assuming exchange by genetic
evolutionary innovations That Appeared randomly).
Attention to the controversy in the US with George Bush, pro-Catholic Who wants to
suit the learning of neo-creationism in schools.