Theory of Evolution
Scientists agree that all living things have developed from simple organisms through a process of change that occurred over millions of years. The exact details are still debated, but a general theory of evolution has existed for more than a century and has been used to explain many observed facts. It is currently used to propose explanations to matters that are beyond those envisioned by its creators, like human behavior.
Interest in the origin of animal species arose in the 18th century when living beings were for the first time scientifically classified. The pioneer work in this field was done by the naturalist Carl von Linne (1707-1778), also known as Carolus Linnaeus. He made a classification of all plants and animals known at his time, and also devised a naming system based on that classification. The name the man received in this classification was 'Homo Sapiens.'
In Linnaeus' time, it was believed that each species was created on its own, either by a divine creator--as thought religious people--or by spontaneous generation from soil or water--the scientific explanation. As his classification was founded on the similarities among the species, it brought into focus these similarities at the same time that other related discoveries were occurring. Two new sciences were emerging: geology and paleontology. Geologists postulated that different layers of rock corresponded to different time periods, and paleontologists acknowledged that fossils belonged to animals that have lived in the past.
The mathematician, physicist, and biologist Pierre L. M. de Maupertuis (1698-1759) had already proposed a theory of evolution when the book of Linnaeus, "Systema Naturae," was published in 1758. However, his theory had little influence. Several naturalists proposed evolution theories until in the 19th century Jean Baptiste de Lamarck (1744-1829) proposed his own. It became so popular--although it was later proved to be wrong--that until today some people cite his example of the long neck of giraffes.
The theory of Lamarck, which became known as 'lamarckism,' was based on the idea that species evolve by the adaptation of animals to their environment. Maupertuis had already supposed that hereditary material was passed from parents to offspring. Lamarck said that giraffes had long necks because they needed to stretch to reach the trees' leaves. Each generation of giraffes thus extends its neck a little and transmits this extension to the next generation. After many generations, the result is that giraffes have a neck long enough to feed themselves.
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