An issue we will be concerning ourselves with in this last part of the course is whether or not we are sufficiently intelligent to be able to effectively "manage" this potential solution.
Important Scientific Milestones in the Early Part of the 19th century
At the beginning of the 19th century, it became recognized that human population growth, may, in fact, be in an unmanageable state.
Thomas Malthus (1766-1834) was an English clergyman, whose writings on population growth had a strong influence on the theory of evolution by natural selection developed by Charles Darwin and Alfred Russel Wallace.
In An Essay on the Principle of Population (1797), Malthus observed that most organisms produce far more offspring than can possibly survive.
Historical Estimates of World Population (accurate to 10--20%)
0.25 Billion
0.30
0.36
0.40
0.36 (three cheers for war and disease!)
0.44
0.35
0.43
0.55
0.47
So during this period of 650 years the world population was stable and fluctuated around a mean value of about 400 million.
Is this the "natural" carrying capacity of the planet?
0.60
0.63
0.82
1.13
1.55
1.75
1.86
2.07
2.30
2.55
6.50
In 1654, Archbishop Usher (Ireland), based on genealogy in Bible, determined that Earth was created October 26, 4004 BC, 9:00am (PST). Therefore, the Earth was 6000 years old.
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A French scholar, Bernard Palissy who lived from 1510-1589 believed the Earth was much older based on his observations that rain, wind, and tides were the cause for much of the present-day appearance of the Earth. He wrote that, these forces could not work over such a short period of time to produce the changes. He was burned at the stake in 1589. A bad time for scientific inquiry. |
Catastrophism:
Abraham Gottlob Werner: (1750-1817)
German geologist who founded the Neptunist school, which proclaimed the aqueous origin of all rocks, in opposition to the Plutonists, or Vulcanists, who argued that granite and many other rocks were of igneous origin.
In the 18th century, rocks were explained in terms of the biblical flood, and were classified into three categories: "primary" for ancient rocks without fossils (believed to precede the flood), "secondary" for rocks containing fossils (often attributed to the flood itself) and "tertiary" for superficial deposits believed to come after the flood.
This led to the theory of catastrophism, that the Earth was shaped by series of giant disasters and that they had to fit many processes into a short time scale.
Can we find any modern day validation of this theory?
Note: Catastrophism was an eighteenth - and nineteenth -
century attempt to reconcile some form of creationism
with the uncomfortable facts of the fossil
record.
Uniformitarianism:
In 1770's, James Hutton, Father of Geology (Scotland, 1726-1797) published `Theory of the Earth' in 1785. Demonstrated that Hadrian's Wall was built by Romans and that after 1500 years there was no change. Thus, he suspected that Earth was much older than 6000 years.
This is the theory of uniformitarianism, that slow processes shape earth. The physical and chemical laws that govern nature are uniform.
According to this theory, there were essentially three stages in a cycle: erosion of rocks produced sediment; sediment built up until eventually its weight generated enough heat to liquefy the bottom layers; and then this molten rock forced its way upwards. The process then started all over again, continuously regenerating the Earth's surface over countless ages, maintaining an environment capable of supporting living animals and plants
Hutton writes: the
Earth functions as a machine whose purpose
is to sustain life
Gradualism
In the mid 1800's, Scottish geoglist Sir Charles Lyell expanded on uniformitarianism to develop gradualism, the view that all features of the Earth's surface are produced by physical, chemical, and biological processes through long periods of geological time.
His system was based on two propositions: the causes of geologic change operating include all the causes that have acted from the earliest time; and these causes have always operated at the same average levels of energy. These two propositions add up to a "steady-state" theory of the Earth. Changes in climate have fluctuated around a mean, reflecting changes in the position of land and sea.
By this time, it is known that the earth has ice ages
Lyell's position suggested that the world had always been (roughly) similar to its current state. In particular, Lyell believed that the species composition of the world remained unchanged, with at least some members of all classes of organisms existing throughout the history of the earth.
Darwin read Lyell's Principles of Geology and came to accept Lyell's view that long-term geological processes were responsible for shaping the earth's surface in a gradual manner.
How does this help of fortify or motivate
Darwin's position on the Origin of Species?
One Reation to Darwin's Proposition
Social Darwinism 
Read Chapter 8 in Burke!
History of Evolution:
The idea of evolution goes back to Jean Lamarck in the early 1800's. Lamarck published a theory of evolution in 1809. Lamarck thought that species arose continually from nonliving sources. These species were initially very primitive, but increased in complexity over time due to some inherent tendency. This type of evolution is called orthogenesis.
Lamarck proposed that an organism's acclimation to the environment could be passed on to its offspring. For example, he thought proto-giraffes stretched their necks to reach higher twigs. This caused their offspring to be born with longer necks. This proposed mechanism of evolution is called the inheritance of acquired characteristics. Lamarck also believed species never went extinct, although they may change into newer forms. All three of these ideas are now known to be wrong.
Even when resources are plentiful, the size of a population tends to increase geometrically until the population outstrips its food supply. This led Malthus to believe that poverty, disease, and famine was a natural and inevitable phenomenon, leading to a "struggle for existence".
Evolution came of age as a science when Charles Darwin published "On the Origin of Species." Darwin's contributions include hypothesizing the pattern of common descent and proposing a mechanism for evolution -- natural selection.
In Darwin's theory of natural selection, new variants arise continually within populations. A small percentage of these variants cause their bearers to produce more offspring than others. These variants thrive and supplant their less productive competitors. The effect of numerous instances of selection would lead to a species being modified over time.
Darwin also recognized several critical facts:
It then follows logically that certain variants will be preserved over time over other variants and that populations will change over time in their composition. This is evolution by natural selection.
The greatest weakness in the theory of evolution by natural selection was the fact that Darwin knew neither how variation among individuals was generated nor how it was inherited.