Jean Baptiste Lamarck (1744 - 1829)
A significant figure on the road to evolution was the French botanist Jean Baptiste Lamarck who held the position of curator of the invertebrate collection at the Natural history museum in Paris. Instead of seeing life as a static ladder of life, he viewed it more as an escalator. On the bottom were microscopic organisms that were continually being formed and driven by an innate tendency to greater complexity, until finally complex plants and animals were at the top of the heap. Lamarck believed that change in organisms was in response to sentiments interieurs, or "felt needs". Lamarck is best known for two notions
a) Use and disuse - Organs that are used increase in size and strength. For example the biceps of a blacksmith would get larger and stronger (legitimate) or by stretching for leaves a giraffe got a long neck (bogus). Other examples are birds who lived in water got webbed feet or moles became blind by living underground, or rams got it's horns by getting mad (ref?)
b) Acquired characteristics - Lamarck believed the changes acquired in organisms lifetime could be passed to the next generation. By this reasoning, the long neck of the giraffe was the gradual result of many generations of stretching and stretching. Biology has of disproved these notions, by experiments such as the cutting off the tails of mice and noting the no decrease in tail length was observed in offspring (Weismann's experiment in the 1891) or considering circumcision over four thousand years.
[Cambell 1987, 427] [Taylor 1991, 45-48]
Photo credits:
http://www.bilimce.net/?p=559
http://www.safarikscience.org/biologyhome/8_evolution/unit_8_home.htm
http://www.canyon-news.com/artman2/publish/shermanoaks/Young_Boy_Trapped_in_Escalator.php