INTRODUCTION The word evolution in its broadest

sense refers to the change or growth that occurs in a particular order.

That use of the term dates back to the ancient Greeks, but today the word is more often used to refer to Darwin's theory of evolution by natural selection.

Although this broad version of the term would include astronomical evolution and the evolution of computer design, our study focuses on the evolution of biological organisms.

ARISTOTELE

Aristotle did not believe in evolution. He based his idea on what is called "The Great Chain of Being". Other names for the same idea are "Ladder of Life" and "Scala Naturae" This was an attempt of classification. Aristotle was trying to understand the relationships among living things. His idea was that all species could be placed in order, from the "lowest" to the "highest", with worms on the bottom and men on the top.

In Aristotle's view, the universe was ultimately perfect, and that meant that the Great Chain was also perfect. That meant that there were no empty links in the chain, and no link was represented by more than one species.

LINNEO

Linneo was a scientist, whose research allowed to find a method to classify the numerous species he had discovered in his travels. His main success was the Binomial Classification (based on the characteristics that some species share), based on the studies of the Bauhin brothers.Binomial classification places the gender name first and the species name follows, in case we find an element that replaces the species name, to make a further differentiation. For example the "Physalis angulata").

LINNEAN TAXONOMYAnother theory of Linneo is "Linnean Taxonomy".In his "Imperium Naturae", Linnaeus established three kingdoms, nameed Regnum Animale, Regnum Vegetabile and Regnum Lapideum. The work of Linnaeus had a huge impact on science; it was indispensable as a foundation for biological nomenclature, now regulated by the Nomenclature Codes. Two of his works, the first edition of the “Species Plantarum” for plants and the tenth edition of the “Systema Naturae”, are accepted as the starting points of nomenclature; his binomials, names for species, and his generic names take priority over those of others.

He divided the Animal Kingdom into six classes, in the tenth edition, of 1758, these were:

Classis 1. Mammalia

Classis 2. Aves

Classis 3. Amphibia

Classis 4. Pisces

Classis 5. Insecta

Classis 6. Vermes

GEORGES CUVIER

Georges Cuvier, was a French naturalist and zoologist and he was a major figure in natural sciences research in the early 19th century. He is well known for establishing extinction as a fact, being the most influential proponent of catastrophism , and opposing the evolutionary theories of Jean-Baptiste de Lamarck.He studied fossils and estabilished the fields of comparative anatomy and paleontology through his work in comparing living animals with fossils.Cuvier is also commemorated in the naming of several animals , such as  Cuvier's beaked whale, Cuvier's Gazelle, Cuvier's toucan, Galeocerdo cuvier (tiger shark), and Anolis cuvieri a lizard from Puerto Rico.

EXTINCTION & CATASTROPHISM

At the time Cuvier presented his 1796 paper on living and fossil elephants, everyone believed that no species of animal had ever become extinct. In fact Buffon declared that fossils found in Europe of animals such as mammoth were rest of animals still living in the tropics. But Cuvier's early work demonstrated definitely that these common beliefs were wrong.In his famous papers he said : “I believe in the existence of a world previous to ours, destroyed by some kind of catastrophe.”

With this sentence he became an active proponent of the geological school of thought called catastrophism.

OPPOSITION TO EVOLUTION

Cuvier did not believe in organic evolution. According to him : “ Any change in an organism's anatomy will make it unable to survive “. He studied the mummified cats and ibises that Geoffroy brought back from Napoleon's invasion of Egypt, and showed that they were not different from their living counterparts. And this is a prove that life forms did not evolve over time.

In fact Cuvier believed that the fossils are only extincted animals after a big catastrophe.

AGE OF REPTILES THEORYIn 1801 Cuvier discovered a fossile , a small flying reptile which he named the Ptero-Dactyle in 1809. A few years later he found another fossile : a giant marine lizard, which he named Mosasaurus . So he speculated that there had been a time when reptiles , rather than mammals, had been the dominant fauna.

This speculation was confirmed in the following 20 years by a series of spectacular foundings such as the first ichthyosaurs, plesiosaurs, and dinosaurs.

JEAN-BAPTISTE LAMARCK

Jean-Baptiste Pierre Antoine de Monet, Chevalier de la Marck (for his friends only Lamarck)  was a French naturalist like Cuvier , but his ideas were very different. In fact , Lamarck was a big supporter of the evolution and his theory is considered the first truly cohesive theory of evolution.

This theory, called “Lamarckian Evolution” is divided into two parts.

The complexifying force

The adaptive force

THE COMPLEXIFYING FORCELamarck referred to a tendency for organisms to become more complex, moving 'up' a ladder of progress. He also call this phenomenon : “The force that perpetually tends to make order”.

He also believed in alchemy and in spontaneous generation , so he tought that  the simple organisms (that continuously and spontaneously were born) transmuted over time becoming more complex , in order to survive.

THE ADAPTIVE FORCE The second component of Lamarck's theory of evolution was the adaptation of organisms to their environment. This could move organisms upward from the ladder of progress into new and distinct forms with local adaptations.Lamarck argued that this adaptive force was powered by the interaction of organisms with their environment, by the use and disuse of certain characteristics.

Another important point to understand this theory is the Inheritance of acquired traits .

To understand the concept of Lamarckism we have to observe the example used by Lamarck … Lamarck’s Giraffe …

Lamark also explain this process with the example of the Blacksmith … he said :

“A blacksmith, through his work, strengthens the muscles in his arms. His sons will have similar muscular development when they mature.” ….

However , with the modern discovery of the DNA , we can say that Lamarck’s theory was wrong . But he put the bases for Darwin’s evolution theory , which is considered the most important .