The current theory, which is accepted by the majority of scientists, the neodarwinistic evolution theory is based on the ideas of Charles Darwin. He however was not the only one who thought about evolution. Read about it in this paragraph.
A Xenofanes (circa 540 v.Chr.) probably was the first man, who referred to the existence of fossils. He realised that the presence of shells and fish-bones proved that these sedimentary deposits had once been situated under water. He found fossils in different layers and concluded that at every border between such layers all plants and animals (including humans) became extinct, after which the living world was created again. This is probably the first example of catastrophe theory in geology.
In the Middle Ages fossils were discovered in Europe now and then. They were often the remains of mammoths from the glacial period. They were regarded as bones belonging to giants. The fossils were kept as curiosities and were shown in churches and in other public places. Probably the most famous discovery was the diluvii testis (man who experienced the Deluge). In 1726 Dr. Johann Jakob Scheuchzer discovered a skeleton in Switzerland, near the village Oeningen, which he thought to belong to a man who had become a victim of the Deluge because he had sinned. In fact the skeleton belonged to a million-years-old salamander.
The famous French naturalist Georges Louis Leclerc Buffon, was one of the first to question the sacred estimation of the age of earth. In Ireland Archbishop Ussher of Armagh calculated that God created Earth in 4004 before Christ, with the help of the number of races mentioned in the Old Testament. Buffon preferred an age of at least 75000 years to explain the slow succession of all large changes in nature. Jean Baptiste Lamarck and the famous Georges Cuvier belonged to his students. Baron Georges Cuvier (1769-1832) was one of the greatest naturalists in history. He proved that fossil skeletons of extinct animals could be rebuilt, that their anatomic qualities could be fixed and compared with the anatomic qualities of living species. In that manner the ways of living of these animals could be reconstructed. Cuvier knew that fossils were the remains of prehistoric life, which had lived thousands of years ago. However, he could not induce himself to include the human race in this global picture. He declared that the fossil man had not existed. His point of view was not taken seriously until about thirty years after his death, when Charles Darwin published his theory about human origins.
The ancient thinkers in Greece and Rome took into account the possibility that animals could change in the course of time. However, their ideas got lost in the early Middle Ages and were replaced by the sacred story in which God created every species separately. However, because of the growing knowledge of comparing anatomy and the acceptation of fossils as evidence of early life, the so-called unchangeable nature of animal-species was less likely. In 1802 Jean Baptiste Lamarck pointed out that species could not be distinguished from each other completely. About seven years later he remarked that everything undergoes a gradual change in the course of time. In his opinion the environment to which the individual had to adapt himself during his life caused this change. The newly acquired qualities should then be passed on to the next generations. So the Lamarckism declares evolution by hereditary transmission of acquired qualities.
Lamarck's theories were not accepted because of two reasons. In the first place his explanation concerning the supposed changes was questioned. The environment does not influence the inheritable qualities of plants and animals directly. Later on, Darwin and Wallace would determine the real mechanism had escaped Lamarck's attention. In the second place Cuvier's point of view that a species developed into another species was not accepted. He totally rejected the application of an evolution theory on mankind.
Charles Darwin came from a family of medical doctors. His father was a medical doctor in Shewsbury and his grandfather, Erasmus Darwin, was a medical doctor and a naturalist. His point of view resembled Lamarck's view. The young Charles was chosen as a naturalist, to take part in a journey of the "Beagle", an exploration ship of the British navy. The voyage to South America and the Pacific Ocean lasted about five years. Darwin collected an enormous quantity of plants, animals and fossils. In this period Darwin's ideas on the origin of species were formed by his observations of plants and animals at the Calāpagos Islands, about a thousand kilometres west of Ecuador. The animals of the Calāpagos Islands resembled those of South America, but were not exactly the same. It was clear that at some point the animals reached these islands from South America somewhere in the past. In the course of time they changed and different, but closely related species, developed.
These observations convinced Darwin that some form of evolution had taken place. He also discovered fossils of large extinct South American mammals, such as the giant sluggard. These discoveries were hard to explain based on the sacred Deluge or the catastrophe theory, which Cuvier adhered to. This, and the conviction that the forming of land came about by means of a mechanism of gradual change, gave cause to Darwin to actually see such a gradual change as the relationship between living and fossil organisms. However, his theory lacked an explanation for the driving force behind these changes.
He got the idea after reading a book written by the economist and clergyman Thomas Malthus in 1798. Malthus believed that unlimited human fertility would lead to overpopulation and famine, because man would exceed his possibilities to produce food: he spoke of a struggle for life. Darwin developed this idea further by suggesting that in that struggle the individuals with favourable characteristics would survive while the other would become extinct. The principal of the "survival of the fittest" as the mechanism for natural selection had been created. The principal was simple; it accounted for the cumulative affect of countless small changes in the course of time, but still had to be proven.
However, Darwin was not the only naturalist thinking in that direction. Zoologist Alfred Russel Wallace also believed in evolution. While Darwin was preparing a book about his theory in 1858, he received a manuscript of Wallace who had come, possibly more intuitive, to almost the same conclusions. Subsequently Darwin consulted his friends and was advised to publicise the theory under both their names and had the book follow at a later stage. In 1858, during a gathering of the Linnean Society in London the mutual essay was presented, in order to give Wallace the honour he deserved