Everything on this Earth seems to be in a continuous flux. There are highly regular changes. The change from day to night and back again, caused by the rotation of the Earth, is such a regular cyclical change. So are the changes of the sea level in the tides, caused by the lunar cycle. Even more pervasive are the seasonal changes due to the annual circling of the Earth around the sun. Other changes are irregular, such as the movements of the tectonic plates, the severity of the winter from year to year, or aperiodic climatic changes (El Nino, ice ages), as well as periods of prosperity in a given nation's economy. Irregular changes are largely unpredictable, being subject to various stochastic processes.
There is, however, one particular kind of change that seems to keep going continuously and to have a directional component. This change is referred to as evolution. The first widespread feeling that the world was not static as implied by the story of Creation, but rather was evolving, can be traced to the eighteenth century.
Eventually it was realized that the static scala naturae could be converted into a kind of biological escalator, leading from the lowest organisms to ever higher ones and finally to man. Just as gradual change in the development of an individual organism leads from the fertilized egg to the fully adult individual, so it was thought that the organic world as a whole moved from the simplest organisms to ever more complex ones, culminating in man.. Evolution, one said, consists of a change from the simple to the complex and from the lower to the higher. Evolution, indeed, was change, but it
seemed to be a directional change, a change toward ever greater perfection, as it was said at that time, not a cyclical change like the seasons of the year or an irregular change like the ice ages or the weather.
Evolutionary thinking spread throughout the second half of the eighteenth and the first half of the nineteenth century, not only in biology but in linguistics, philosophy, sociology, economics, and other branches of thought. Yet, on the whole, in science it remained for a long time a minority view. The actual shift from the
belief in a static worldview to evolutionism was caused by the dramatic event of the publication of Charles Darwin's On the Origin of Species on the 24th of November in 1859.
